Article

An automated GIS procedure for comparing GPS and proximal LIDAR elevations

July 2006
Computers & Geosciences 32(6):713-726

DOI:10.1016/j.cageo.2005.08.009

Authors:

Nova Scotia Community College

High-resolution elevation surveys utilizing light detection and ranging (LIDAR) are becoming available to the geoscience community to derive high-resolution DEMs that are used in a variety of application areas. However, prior to the application of these data to geomorphic interpretation, extensive validation procedures should be employed. The vertical accuracy specification for the survey called for heights to be within an average of 15cm of measured GPS heights and 95% of the data to be within 30cm. Two different LIDAR systems and collection methods were employed to collect data for the study area located in the Mesozoic Fundy Basin in eastern Canada. High-precision GPS surveys were conducted to measure the ground elevations in open areas and a traditional topographic survey was carried out in order to assess the accuracy of the laser data under the forest canopy. The LIDAR and validation data were integrated into a GIS where an automated procedure was developed that allows the user to specify a search radius out from the validation points in order to compare proximal LIDAR points. This procedure facilitates examining the LIDAR points and the validation data to determine if there are any systematic biases between flight lines in the LIDAR data. The results of the validation analysis of the two LIDAR methods and a description of the automated procedure are presented in this paper.

Liu X. Airborne LiDAR for DEM generation: Some critical issues. Progress in Physical Geography

Article

Feb 2008
PROG PHYS GEOG

Xiaoye Liu

Airborne LiDAR is one of the most effective and rel iable means of terrain data collection. Using LiDAR data for DEM generation is becoming a standard practice in spatial related areas. However, the eff ective processing of the raw LiDAR data and the generation of an efficient and high-qu ality DEM remain big challenges. This paper reviews the recent advances of airborne LiDAR systems and the use of LiDAR data for DEM generation, with special focus on LiDAR data filters, interpolation methods, DEM resolution, and LiDAR data reduction. Separating LiDAR points into ground and non-ground is the most critical and difficult step for DEM generation from LiDAR data. Commonly used and most recently developed LiDAR filtering methods are presented. Interpolatio n methods and choices of suitable interpolator and DEM resolution for LiDAR DEM generation are discussed in detail. In order to reduce the data redundancy and increase the efficiency in terms of storage and manipulation, LiDAR data reduction is required in the process of DEM generation. Feature specific elements such as break lines contribute significantly to DEM quality. Therefore, data reduction should be co nducted in such a way that

Mapping subtle structures with light detection and ranging (LIDAR): Flow units and phreatomagmatic rootless cones in the North Mountain Basalt, Nova Scotia

Article

Full-text available

Feb 2011

Light detection and ranging (LIDAR) is an emerging technology to generate high-resolution digital elevation models (DEMs). Subtle topographical differences among three flow units of the Jurassic North Mountain Basalt, eastern Canada, are visible on a LIDAR-derived DEM. The boundaries were verified by field mapping and allow a simple projection of the contact planes through the terrain model to provide a three-dimensional visualization of the flow units. Several ring structures in the lower flow unit, distinguishable only in the LIDAR data, are interpreted to be the remnants of rootless phreatomagmatic cones. Glacial erosion has since excavated the highly fractured cone material, leaving the more resistant dike and quenched melt to form protruding ring structures. The ability to detect subtle variations in topography using LIDAR may identify previously undetected landscape elements.

The application of LiDAR-derived digital elevation model analysis to geological mapping: an example from the Fundy Basin, Nova Scotia, Canada

Article

Full-text available

Apr 2006

High-resolution laser altimetry (lidar) is applied to geological problems such as bedrock and surficial mapping and the relationship to earth surface processes in the Fundy Basin of Nova Scotia. A "bald earth" lidar digital elevation model (DEM) is used in conjunction with field observations to map three flow units of the Jurassic North Mountain Basalt (NMB) based on contrasting terrain characteristics (slope, smoothness, and relief). The variable resistance of the flow units to erosion, documented by shatterbox experiments and down-core fracture density data, has a measurable control on incision by post-glacial consequent streams. In catchments where till cover is thick, greater surface runoff and weaker infiltration increase incision by as much as 43% for a given flow unit Interpretation of field, petrologic, and digital topography data indicates previously unrecognized craters in the lower flow unit are the result of interaction between partially solidified lava and surface water or groundwater. Two new sets of surficial landforms have been identified that indicate ice was directed northwestward into the Bay of Fundy during the late stages of glaciation. Twice as many wave-cut terraces have been identified in the lidar DEM than previously mapped, and elevations have been extracted and compared with published values that are related to higher sea-levels at 12-14 ka. This paper demonstrates through a range of examples that the precision and enhanced resolution of lidar can improve our understanding of how landscapes form and evolve.

LiDAR-Derived High Quality Ground Control Information and DEM for Image Orthorectification

Article

Mar 2007

Orthophotos (or orthoimages if in digital form) have long been recognised as a supplement or alternative to standard maps. The increasing applications of orthoimages require efforts to ensure the accuracy of produced orthoimages. As digital photogrammetry technology has reached a stage of relative maturity and stability, the availability of high quality ground control points (GCPs) and digital elevation models (DEMs) becomes the central issue for successfully implementing an image orthorectification project. Concerns with the impacts of the quality of GCPs and DEMs on the quality of orthoimages inspire researchers to look for more reliable approaches to acquire high quality GCPs and DEMs for orthorectification. Light Detection and Ranging (LiDAR), an emerging technology, offers capability of capturing high density three dimensional points and generating high accuracy DEMs in a fast and cost-effective way. Nowadays, highly developed computer technologies enable rapid processing of huge volumes of LiDAR data. This leads to a great potential to use LiDAR data to get high quality GCPs and DEMs to improve the accuracy of orthoimages. This paper presents methods for utilizing LiDAR intensity images to collect high accuracy ground coordinates of GCPs and for utilizing LiDAR data to generate a high quality DEM for digital photogrammetry and orthorectification processes. A comparative analysis is also presented to assess the performance of proposed methods. The results demonstrated the feasibility of using LiDAR intensity image-based GCPs and the LiDAR-derived DEM to produce high quality orthoimages.

Ground truth extraction from LiDAR data for image orthorectification

Conference Paper

Jun 2008

The availability of high accuracy GCPs (ground control points) and DEMs (digital elevation models) becomes the key issue for successful implementation of an image orthorectification project. It is a very difficult task for collecting a large number of high quality GCPs by using traditional methods to meet all the requirements for digital photogrammetric and orthorectification process. Airborne light detection and ranging (LiDAR) - also referred to as airborne laser scanning (ALS), provides an alternative for high-density and high-accuracy three-dimensional terrain point data acquisition. One of the appealing features in the LiDAR output is the direct availability of three dimensional coordinates of points and intensity data in object space. With LiDAR data, high- accuracy and high-resolution intensity image, hillshade DSM (digital surface model) image, and DEM can be generated. Due to high planimetric accuracy characteristics of LiDAR data, ground truth can be extracted from these LiDAR-derived products (e.g., hillshade image and intensity image). This study investigated the feasibility of using LiDAR-derived hillshade DSM image and intensity image to extract ground truth for aerial image orthorectification. Two sets of GCPs were extracted from hillshade image and intensity image separately, and then were used as the inputs for aerial triangulation processing. LiDAR- derived DEM was then employed for differential rectification to produce the final orthoimage. The assessment of the planimetric accuracy of orthorectified images by using different set of GCPs was conducted by comparing the coordinates of some checking points from orthoimages and correspondent GPS surveyed coordinates.

The Highest Peaks of the Mountains: Comparing the Use of GNSS, LiDAR Point Clouds, DTMs, Databases, Maps, and Historical Sources

Article

Full-text available

Sep 2021

Advances in remote data acquisition techniques have contributed to the flooding of society with spatial data sets and information. Widely available spatial data sets, including DTMs from ALS data, are finding more and more new applications. The article analyses and compares the heights of the 14 highest peaks of the Polish Carpathians derived from different data sources. GNSS geodetic measurements were used as reference. The comparison primarily involves ALS data, for selected peaks GNSS measurements carried out with Xiaomi Mi 8 smartphones were also compared. Recorded raw smartphones GNSS measurements were used for calculations in post-processing mode. Other data sources were, among others, global and local databases and models and topographic maps (modern and old). The article presents an in-depth comparison of Polish and Slovak point clouds for two peaks. The results indicate the possible use of large-area laser scanning in determining the maximum heights of mountain peaks and the need to use geodetic GNSS measurements for selected peaks. For the Polish peak of Rysy, the incorrect classification of point clouds causes its height to be overestimated. The conclusions presented in the article can be used in the dissemination of knowledge and to improve positioning methods.

Remote Predictive Mapping 5. Using a Lidar Derived DEM to Test the Influence of Variable Overburden Thickness and Bedrock on Drainage and Basin Morphology

Article

Full-text available

Mar 2014

A 4–m lidar digital elevation model (DEM) provides sufficient resolution to examine the impact of variable till cover on the incision history of multiple small (5 km2) catchments in eastern Canada. The study site was selected because it has homogeneous bedrock geology that dips parallel to the land surface, is tectonically stable, has undergone common base level changes, and has a common ice history, with variable overburden thickness, from thin cover in the west to thick cover in the east. Basin morphometrics were compared for similar-size basins that have variable till cover thicknesses. Basins with thicker till cover are wider and show differences in hypsometries compared to those where till cover is thin. Two basins representing end members of till thickness were measured for stream discharge and water chemistry. Thick till (> 1 m) on the eastern half of North Mountain retards infiltration sufficiently to promote overland flow and accelerate incision relative to areas with thinner till. Till thickness and continuity therefore are expected to impede the achievement of steadiness and may also delay stream power law relationships in larger catchments until till cover has been effectively eroded.

Vertical accuracy assessment of LiDAR ground points using minimum distance approach

Article

Full-text available

Jan 2014

Light Detection And Ranging is now being widely used to provide accurate digital elevation model (DEM). One common method used to determine the accuracy of LiDAR - Light Detection And Ranging - vertical accuracy is compared LiDAR-derived DEM elevation with survey-derived ground control points (GCPs). However, because the DEM elevations are generalised to the areas covered by one cell, inherent errors when compared to the elevation of a GCP are evident. This paper presents a method based on a minimum distance approach using the so called first law of geography to assess the accuracy of LiDAR ground point dataset. The result has shown that the tested LiDAR ground point dataset is suitable for applications that do not need a vertical accuracy better than 0.5m.

THE EMERGING ROLE OF LIDAR REMOTE SENSING FOR HYDROLOGICAL APPLICATION: OPPORTUNITIES AND CONSTRAINTS

Conference Paper

Full-text available

Dec 2010

Light Detection And Ranging (LiDAR) is a modern technology which has been accepted as standard-tool for collecting high-resolution topographic data around the world. Recognizing the recent development in LiDAR remote sensing and its vast potential in hydrological studies, this paper briefly describes the principle and technical issues related with topographical LiDAR and hydrographic LiDAR technology. The various accuracy aspects and advantages of LiDAR over other conventional methods of terrain data generation have also been discussed. Further, the various potential area of hydrological science wherein LiDAR data can be used has been successfully reviewed to give the reader an understanding of current traditional practices. However, the existence of some technical problems with LiDAR data generation and processing hinder it widespread usage for hydrological and other resource application. Hence, at the end, the paper highlighted the constraints of LiDAR data for its hydrological application. It is believed that this paper will underscores the emerging salient role of LiDAR remote sensing in hydrological research and resource management, and will inspire the scientific community to tap this remarkable new technology.

Modeling Blister Rust Incidence in Whitebark Pine at Northern Rocky Mountain Alpine Treelines: A Geospatial Approach

Article

The use of medium point density LiDAR elevation data to determine plant community types in Baltic coastal wetlands

Article

Oct 2013

Accuracy Assessment of Lidar Elevation Data Using Survey Marks

Article

Jan 2011

Xiaoye Liu

Airborne LiDAR has become the preferred technology for digital elevation data acquisition in a wide range of applications. The vertical accuracy with respect to a specified vertical datum is the principal criterion in specifying the quality of LiDAR elevation data. The quantitative assessment of LiDAR elevation data is usually conducted by comparing high-accuracy checkpoints with elevations estimated from the LiDAR ground data. However, the collection of a sufficient number of checkpoints by field surveying is a time-consuming task. This study used survey marks to assess the vertical accuracy of LiDAR data for different land covers in a rural area and explored the performance of different methods for deriving elevations from LiDAR data corresponding to the locations of checkpoints. Normality tests using both frequency histograms and quantile-quantile plots were performed for vertical differences between the LiDAR data and the checkpoints, so the appropriate measures (the formula 1.96×RMSE or the 95 th percentile) can be used for the vertical accuracy assessment of the LiDAR data for different land covers. The results demonstrated the suitability of using survey marks as checkpoints for the assessment of the vertical accuracy of LiDAR data.

Determine stormwater pond geometrics and hydraulics using remote sensing technologies: A comparison between airborne-LiDAR and UAV-photogrammetry field validation against RTK-GNSS

Article

Full-text available

May 2023

Flow-regulated stormwater ponds providing safe outflow discharges prevail as the primary stormwater management tool for stream protections. Detailed pond geometries are essential metrics in pond monitoring technologies, which convert the point-based water level measurements to areal/volumetric ponding water estimations. Unlike labour-intensive surveys (e.g., RTK-GNSS or total stations), UAV-photogrammetry and airborne-LiDAR have been advocated as cost-effective alternatives to acquire high-quality datasets. In this paper, we compare the use of these two approaches for stormwater pond surveys. With reference to RTK-GNSS in-situ observations, we identify their geometric and hydraulic discrepancies based on six stormwater ponds from three aspects: (i) DEMs, (ii) stage-curves and (iii) outflow discharges. Three main findings are outlined: (i) for wet ponds where moisture environments are dominant, UAV-photogrammetry outperforms airborne-LiDAR, where airborne-LiDAR yields 0.15–0.54 NSEoutflow, which is unacceptable; (ii) for dry ponds, UAV-photogrammetry obtains 0.88–0.89 NSEoutflow as poor vegetation penetrations; two correction methods (i.e., grass removal and shifted stage-curves) are proposed, indicating good alignment to RTK-GNSS observations and (iii) UAV-photogrammetry delivers <0.1 m resolution in outlining break-line features for stormwater pond structures. With significant economic advantages, the multi-UAV collaborative photogrammetry would address the shortcomings of a single UAV and thus pave the way for large-scale survey applications.

Quantification of Surface Pattern Based on the Binary Terrain Structure in Mountainous Areas

Article

Full-text available

May 2023

Terrain significantly influences the physical processes and human activities occurring on the Earth’s surface, especially in mountainous areas. The classification and clarification of topographic structures are essential for the quantitative analysis of surface patterns. In this paper, we propose a new method based on the digital elevation model to classify the binary terrain structure. The slope accumulation is constructed to emphasize the accumulated topographic characteristics and is applied to support the segmenting process. The results show that this new method is efficient in increasing the completeness of the segmented results and reducing the classification uncertainty. We verify this method in three areas in South America, North America and Asia to evaluate the method’s robustness. Comparison experiments suggest that this new method outperforms the traditional method in areas with different landforms. In addition, quantitative indices are calculated based on the segmented results. The results indicate that the binary terrain structure benefits the understanding of surface patterns from the perspectives of topographic characteristics, category composition, object morphology and landform spatial distribution. We also assess the transferability of the proposed method, and the results suggest that this method is transferable to different digital elevation models. The proposed method can support the quantitative analysis of land resources, especially in mountainous areas and benefit land management.

Estimation of crop and forest biomass resources in a semi-arid region using satellite data and GIS

Article

Apr 2021

In India the demand of sustainable energy is growing at a fragmented level. The demand of rural electrification and economic growth requires high production of energy. Hence, the use of renewable energy may help to mitigate air pollution, and allow specific regenerative agriculture, waste, and forest biomass for producing the energy and achieving sustainable development goals. In the current work, we have selected a district of Maharashtra state of India as a case study and mapped the different land cover categories , and their estimated biomass. Based on this we have prepared the biomass thematic maps for the study area. These biomass maps have been prepared in the GIS environment and they displayed the bio-mass of crops, forests, and wastelands. The studied district has huge potential for agricultural biomass and can act as biofuel and biomass economies. These maps may play a crucial role in upgrading biomass sites focused on generating power from plants in the district Akola of Maharashtra, India. Ó 2021 The Authors. Production and hosting by Elsevier B.V. on behalf of King Saud University. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).

Landslide Hazard in a Changing Environment

Book

Full-text available

Mar 2019

Landslides are one of the most dangerous geomorphological processes, responsible for losses of human lives and damages to structures, infrastructures, cultural and natural heritage. During the Anthropocene, impacts of human activity on the environment, including recent climate changes, have caused deep alterations to the natural evolution of surficial geologic processes, causing a progressive increase in the occurrence of landslides. The goal of this Research Topic is to provide an updated overview of the progress in the field of landslide research, covering all the aspects related to the landslide events: geomorphological characterization and understanding of triggering and predisposing factors, new technologies applied to the study of evolution of slope phenomena, new methodologies to foresee and mitigate landslide hazard.

Evaluating the Differences of Gridding Techniques for Digital Elevation Models Generation and Their Influence on the Modeling of Stony Debris Flows Routing: A Case Study From Rovina di Cancia Basin (North-Eastern Italian Alps)

Article

Full-text available

Nov 2018

Debris flows are among the most hazardous phenomena in mountain areas. To cope with debris flow hazard, it is common to delineate the risk-prone areas through routing models. The most important input to debris flow routing models are the topographic data, usually in the form of Digital Elevation Models (DEMs). The quality of DEMs depends on the accuracy, density, and spatial distribution of the sampled points; on the characteristics of the surface; and on the applied gridding methodology. Therefore, the choice of the interpolation method affects the realistic representation of the channel and fan morphology, and thus potentially the debris flow routing modeling outcomes. In this paper, we initially investigate the performance of common interpolation methods (i.e., linear triangulation, natural neighbor, nearest neighbor, Inverse Distance to a Power, ANUDEM, Radial Basis Functions, and ordinary kriging) in building DEMs with the complex topography of a debris flow channel located in the Venetian Dolomites (North-eastern Italian Alps), by using small footprint full-waveform Light Detection And Ranging (LiDAR) data. The investigation is carried out through a combination of statistical analysis of vertical accuracy, algorithm robustness, and spatial clustering of vertical errors, and multi-criteria shape reliability assessment. After that, we examine the influence of the tested interpolation algorithms on the performance of a Geographic Information System (GIS)-based cell model for simulating stony debris flows routing. In detail, we investigate both the correlation between the DEMs heights uncertainty resulting from the gridding procedure and that on the corresponding simulated erosion/deposition depths, both the effect of interpolation algorithms on simulated areas, erosion and deposition volumes, solid-liquid discharges, and channel morphology after the event. The comparison among the tested interpolation methods highlights that the ANUDEM and ordinary kriging algorithms are not suitable for building DEMs with complex topography. Conversely, the linear triangulation, the natural neighbor algorithm, and the thin-plate spline plus tension and completely regularized spline functions ensure the best trade-off among accuracy and shape reliability. Anyway, the evaluation of the effects of gridding techniques on debris flow routing modeling reveals that the choice of the interpolation algorithm does not significantly affect the model outcomes.

The use of RPAS for the development of land surface models for natural resources management: a review

Article

Jan 2018

The use of RPAS for the development of land surface models for natural resources management: a review

Article

Jan 2018

Rockfall Hazard Assessment: An Overview

Chapter

May 2017

Rockfalls are landslides that exhibit mass movements and highly varied volume and that involve rock masses ranging from several cubic centimeters to thousands of cubic meters. Rockfalls happen when rock masses are detached from a cliff face and freely fall under the effect of gravity.

Using Lidar Elevation Data to Develop a Topobathymetric Digital Elevation Model for Sub-Grid Inundation Modeling at Langley Research Center

Article

Full-text available

Dec 2016

Technological progression in light detection and ranging permits the production of highly detailed digital elevation models, which are useful in sub-grid hydrodynamic modeling applications. Sub-grid modeling technology is capable of incorporating these high-resolution lidar-derived elevation measurements into the conventional hydrodynamic modeling framework to resolve detailed topographic features for inclusion in a hydrological transport model for runoff simulations. The horizontal resolution and vertical accuracy of the digital elevation model is augmented via inclusion of these lidar elevation values on a nested 5-m sub-grid within each coarse computational grid cell. This AIDS in resolving ditches and overland drainage infrastructure at Langley Research Center to calculate runoff induced by the heavy precipitation often accompanied with tropical storm systems, such as Hurricane Irene (2011) and Hurricane Isabel (2003). Temporal comparisons of model results with a NASA tide gauge during Hurricane Irene yielded a good R² correlation of 0.97, and root mean squared error statistic of 0.079 m. A rigorous point-to-point comparison between model results and wrack line observations collected at several sites after Hurricane Irene revealed that when soil infiltration was not accounted for in the model, the mean difference between modeled and observed maximum water levels was approximately 10%. This difference was reduced to 2-5% when infiltration was considered in the model formulation, ultimately resulting in the sub-grid model more accurately predicting the horizontal maximum inundation extents within 1.0-8.5 m of flood sites surveyed. Finally, sea-level rise scenarios using Hurricane Isabel as a base case revealed future storm-induced inundation could extend 0.5-2.5 km inland corresponding to increases in mean sea level of 37.5-150 cm.

New methodological approach for biomass resource assessment in India using GIS application and land use/land cover (LULC) maps

Article

Sep 2016
RENEW SUST ENERG REV

India has a high potential for technically recoverable biomass, sufficient to meet part of its increasing energy needs, promote energy access in rural and remote areas, create economic opportunities at the national scale, and reduce indoor pollution. Effective utilization of surplus biomass resources is often challenged and hindered by seasonal availability, extensive distribution over vast and distanced areas, and the embedded socio-cultural factors associated with its use. Therefore, the development of reliable maps for the assessment of available/surplus biomass resources is the first key step toward the creation of a new supply chain for cost-effective bioenergy production, particularly in developing countries. In this paper, a new methodological approach that combines primary and secondary data sets, social factors, remote sensing data, and software, such as GIS applications, has been developed. The main goal is to create high-quality, land use/land cover (LULC) maps for agricultural and wastelands in India. With an acceptable level of accuracy assessment, the paper also determines the surplus biomass resources in wastelands and municipal solid waste (MSW) distribution in three Indian states: Madhya Pradesh, Maharashtra, and Tamil Nadu. These states were selected due to the high level of agriculture production and thus high agro-biomass potential, the presence of large industrial agglomerations, and the high interest in bioenergy development in these states. The maps show that the highest surplus biomass from wastelands exists in Madhya Pradesh, while high MSW potentials exist in Maharashtra state. The developed maps considered the existing uses of biomass in order to calculate the surplus biomass resources. The presented maps are a useful tool to optimize the locations of biomass-based and/or co-generation power plants in the surveyed states.

GPS YER KONTROL NOKTALARI KULLANILARAK LiDAR VERİSİNİN DOĞRULUK ANALİZİ

Article

Full-text available

Mar 2016

Nowadays, both faster and more accurate data acquisition studies are gradually gaining speed, different of traditional land surveying technics in order to obtain land data having high accuration and geometric resolution on mapping. In this study, it is aimed that, to test with RTK/GPS (Real Time Kinematic-Global Positioning System) data of LiDAR (Light Detection and Ranging) Technology, as Remote Sensing Technic, making detection at 1.064nm near infrared region of electromagnetic spectrum in terms of planimetric and vertical accuracy. İn this context, 2x2 km2 forested land, located in Borçka province of Artvin City in the Eastern Black Sea Region of Turkey was selected as study area. In this study, position and elevation differences were estimated between Ground Control Points (GCP) acquired by RTK- and the corresponding LiDAR points, and then, the relationship between the accuracies of these values was tested with search radius method as compared with. Vertical error (RMSEz) was found as 0.20m in normal distribution while it was 0.39 m, vertical accuracy (accuracyz) in 95% confidence interval, Planimetric error (RMSEr) was found as minimum 0.36m, maximum 1.01m, while it was minimum 0.62m, maximum 1.75m planimetric accuracy (accuracyr) in 95% confidence interval. As a result, it was seen that the horizontal error was as twice as the vertical error.

Spatio-temporal Analysis of Earth’s Surface Deformation by GPS and InSAR Data

Conference Paper

Jun 2014
Lect Notes Comput Sci

We present elements of technology for spatio-temporal data mining aimed at studying natural processes by temporal sequences. The methods considered are applied to the analysis of Earth’s surface deformations by GPS and InSAR measurements of ground displacements. Often, the study of earth deformation is limited to the analysis of average strain rates only. It is shown that inclusion of the temporal component of GPS data allows one to find the relationship between seismicity and dynamics of the fields of horizontal surface deformations. Accounting for the temporal component of InSAR data allows identifying urban areas of land, which differ not only in the intensity of deformations process, but also in the type of their dynamics. The methods considered are realized in GIS GeoTime 3 (http://www.geo.iitp.ru/GT3/).

Geomorphometry

Chapter

Mar 2013

The study of surface processes and landforms requires quantitative characterization of the topography. New theoretical/conceptual and practical advances in understanding and mapping various aspects of geomorphological systems have emerged from new geospatial data and analysis of the topography. This chapter describes geomorphometry, or the science of quantitative land-surface characterization, and how it can be used to represent and sample the land surface, generate digital elevation models (DEMs), correct errors and artifacts from surface models, compute land-surface parameters and objects, and use various forms of quantitative information in different application domains to address or solve problems.

Application of gamma-ray spectrometer data for lithological mapping in a cordilleran environment, Sekwi Region, NWT

Article

Full-text available

Jun 2014

Gamma-ray spectrometry, magnetic, and Landsat data are evaluated for producing a predictive lithological map of a cordilleran environment (Sekwi region) in the Northwest Territories using supervised classification. Two approaches for defining training areas were used to conduct a maximum likelihood classification of the various datasets separately and in combination. The first approach involved defining training areas on an existing geological map in concert with evaluation of spectral, radiometric, and magnetic signatures. The second uses field locations as training areas. Validation of the classified maps was performed by comparing them to check training areas and existing geological maps. Both training methods produced similar predictive maps (classifications), and in this geologic environment from an individual perspective the gamma-ray spectrometry data produced more accurate results than the magnetic and Landsat data. However, the “best” map was produced using all the gamma-ray data, together with the residual magnetic total field data, and the Landsat data, supporting the notion that a variety of geoscience data, each responsive to different characteristics of rocks (spectral reflectance, radioelement concentrations, and magnetic susceptibility), provides the most accurate predictive map.

Validation of High-Density Airborne LiDAR-Based Feature Extraction Using Very High Resolution Optical Remote Sensing Data

Article

Full-text available

Dec 2013

This work uses the canopy height model (CHM) based workflow for individual tree crown delineation from LiDAR point cloud data in an urban environment and evaluates its accuracy by using very high-resolution PAN (spatial) and 8-band WorldView-2 imagery. LiDAR point cloud data were used to detect tree features by classifying point elevation values. The workflow includes resampling of LiDAR point cloud to generate a raster surface or digital terrain model, generation of hill-shade image and intensity image, extraction of digital surface model, generation of bare earth digital elevation model and extraction of tree features. Scene dependent extraction criteria were employed to improve the tree feature extraction. LiDAR-based refining/filtering techniques used for bare earth layer extraction were crucial for improving the subsequent tree feature extraction. The PAN-sharpened WV-2 image (with 0.5 m spatial resolution) used to assess the accuracy of LiDAR-based tree features provided an accuracy of 98%. Based on these inferences, we conclude that the LiDAR-based tree feature extraction is a potential application which can be used for understanding vegetation characterization in urban setup. Keywords: LiDAR; WorldView-2; Feature Extraction

Monitoring coastal change using terrestrial LiDAR

Article

Full-text available

Dec 2010

The paper describes recent applications by the British Geological Survey (BGS) of the technique of mobile terrestrial Light Detection And Ranging (LiDAR) surveying to monitor various geomorphological changes on English coasts and estuaries. These include cliff recession, landslides and flood defences, and are usually sited at remote locations undergoing dynamic processes with no fixed reference points. Advantages, disadvantages and some practical problems are discussed. The role of GPS in laser scanning is described.

Object-oriented land cover classification of LIDAR-derived surfaces

Article

Full-text available

Apr 2006

Light detection and ranging (lidar) provides high-resolution vertical and horizontal spatial data and has become an important technology for generating digital elevation models (DEMs) and digital surface models (DSMs). The latest terrestrial lidar sensors record intensity and echo information for each pulse in addition to range. In this study, lidar height and intensity data were used to classify land cover using an object-oriented approach. The study area was selected based on the variety of land cover types present and consists of urban, mixed forest, and wetland-estuary coastal environments. Surfaces constructed from the lidar points included DSM, DEM, intensity, multiple echos, and normalized height. These surfaces were segmented and classified using object rule based classification. Ten classes were extracted from the lidar data, including saturated and non-saturated intertidal sediments, saturated or stressed and lush ground cover vegetation, low and tall deciduous and coniferous trees, roads and bare soil, bright-roofed structures, dark-roofed structures, and water. The accuracy of the classification was assessed using independent ground reference polygons interpreted from colour orthophotographs and intensity images. The average accuracy of the 10 classes was 94%, but improved to 98% when the classification results were aggregated into seven classes. The results indicate that accurate land cover maps can be generated from a single lidar survey using the derived surfaces, and that image object segmentation and rule-based classification techniques allow the exploitation of spectral and spatial attributes of the lidar data.

Digital terrain modeling

Article

Jan 2012
GEOMORPHOLOGY

John P Wilson

This article examines how the methods and data sources used to generate DEMs and calculate land surface parameters have changed over the past 25years. The primary goal is to describe the state-of-the-art for a typical digital terrain modeling workflow that starts with data capture, continues with data preprocessing and DEM generation, and concludes with the calculation of one or more primary and secondary land surface parameters. The article first describes some of ways in which LiDAR and RADAR remote sensing technologies have transformed the sources and methods for capturing elevation data. It next discusses the need for and various methods that are currently used to preprocess DEMs along with some of the challenges that confront those who tackle these tasks. The bulk of the article describes some of the subtleties involved in calculating the primary land surface parameters that are derived directly from DEMs without additional inputs and the two sets of secondary land surface parameters that are commonly used to model solar radiation and the accompanying interactions between the land surface and the atmosphere on the one hand and water flow and related surface processes on the other. It concludes with a discussion of the various kinds of errors that are embedded in DEMs, how these may be propagated and carried forward in calculating various land surface parameters, and the consequences of this state-of-affairs for the modern terrain analyst.

GIS Modelling of Intertidal Wetland Exposure Characteristics

Article

Full-text available

Jun 2011
J COASTAL RES

Exposure to solar radiation and tidal inundation are important factors for a wide variety of chemical and ecological processes in coastal ecosystems. Accurate quantification of these factors is often difficult on a local scale. To address this research gap, a remote-sensing approach was developed to model inundation and radiation characteristics within an intertidal zone located in the Minas Basin (Bay of Fundy, Nova Scotia, Canada). A light detection and ranging (LIDAR)–derived elevation model was subjected to tidal modelling based on hourly sea level predictions and solar modelling based on sunrise and sunset times for 2009. Model results indicated an intertidal zone of 145.8 km2 with an elevation between −6.9 m and 6.8 m. The intertidal zone was determined to contain three unique wetland classes: (1) 4.4 km2 of high salt marsh, dominated by Spartina patens; (2) 5.0 km2 of low salt marsh, dominated by Spartina alterniflora; and (3) 63.1 km2 of nonvegetated marine flat (73.3 km2 unclassified intertidal). Detailed exposure characteristics were calculated for each of the classes within the intertidal zone at 10-cm vertical intervals. Exposure calculations for 2009 showed that an average of 4.2 km2 of salt marsh were exposed to solar radiation and 8.4 km2 were exposed to the atmosphere each hour. Similarly, 11.7 km2 of marine flat were exposed to solar radiation and 22.9 km2 were exposed to the atmosphere each hour. The developed remote-sensing techniques successfully established intertidal zones, uniquely identified wetland classes, and modelled inundation and solar exposure characteristics within the study area.

Evaluation of digital terrain models generated in forest conditions from airborne laser scanning data acquired in two seasons

Article

Aug 2011

Airborne laser scanners (ALS) provide accurate data for digital terrain model (DTM) construction. Because of a small number of experiences, ALS-based DTMs should be tested widely in a variety of forest environments. In this study, a series of DTMs were produced from ALS data, acquired twice in one year (spring/summer). The study was carried out in a 1000-ha forested area in Poland. Spatial resolutions of output DTMs, season of data acquisition, number of vegetation layers and tree species in the first forest floor were evaluated to assess their influence on the DTM errors. Surveying methods were used to collect coordinates of 95 checkpoints. For various output raster resolutions and seasons of data acquisition, mean errors varied between �0.2 and 0.34 m, and root mean square errors varied from 0.28 to 0.79 m. Errors increased linearly with DTM pixel size, and their variability was significantly higher in DTMs derived from summer data than in DTMs derived from spring data. Effects of seasonality were modified by both forest structure and species composition. One-layer stands were more sensitive to season of data acquisition than were multilayer stands, as were larch and alder stands in comparison to pine and oak stands.

Improving LiDAR Height Precision in Urban Environment: Low-Cost GNSS Ranging Prototype for Post-Mission Airborne Laser Scanning Enhancement

Article

May 2024

Although Light Detection and Ranging (LiDAR) technology is currently one of the most efficient methods for acquiring high-density point cloud, there are still challenges in terms of data reliability. In particular, the accuracy assessment of LiDAR data, especially in the height component, is one of the main issues in this context. This study introduces a rapid and cost-effective platform to improve the accuracy and precision of LiDAR data by integrating high-density GNSS-Ranging measurements with LiDAR data. The platform offers the capability to rapidly collect a significant number of network real time kinematic (NRTK) points with centimetric precision. A continuous correction surface is proposed to integrate the platform and LiDAR data, resulting in improved accuracy for all ground-class LiDAR data. Evaluation using GNSS benchmarks and NRTK checkpoints showed a significant reduction in LiDAR height errors after applying the correction surface. The root mean squares error (RMSE) decreased from 18.5 cm to 8.2 cm when compared to GNSS benchmarks and from 17.4 cm to 5.3 cm for approximately 1000 NRTK control points. The results indicate that collecting a large number of high-density GNSS ground targets and applying a correction surface to LiDAR height data significantly enhance the accuracy and precision of the LiDAR extracted products.

Assessing UAV-Based Wild Blueberry Plant Height Mapping - A Consideration for Wild Blueberry Harvester Automation

Article

Apr 2024

Accuracy Management of LiDAR Data Using GPS Ground Control Points

Article

Mar 2016

References

Chapter

Feb 2018

John P. Wilson

Integration of field investigations and remote sengin techniques for the assessment of landslide activity and damage

Thesis

Full-text available

May 2017

Matteo Del Soldato

The aim of the PhD thesis was to look for a relationship between the landslide-induced damage recorded on structures and facilities based on the results of several field campaigns and kinematic parameters quantitatively estimated by remote sensing techniques. Investigations were developed on two test sites: a deep-seated landslide in Colle Lapponi-Piano Ovetta in municipality of Agnone (Molise region, southern Italy) and the landslides affecting the southwestern sector of Volterra (Tuscany region, central Italy). First of all, a re-enactment of the evolution of both landslides were conducted, by means of 3D reconstructions based on historical aerial series of images and the analysis of Persistent Scatterers of ERS1/2, ENVISAT and COSMO-SkyMed satellites. The 3D Points Clouds and models were developed on several sets of aerial historical images dating from different years starting from 1945 and 1954 for Agnone and Volterra, respectively. To better understand the morpho-evolutionary stages, a qualitative assessment of changes of volume were made combining the oldest and the latest 3D reconstructed Points Clouds. This interpretation, even if qualitative and not quantitative, can be helpful for understanding possible effects of future reactivations and as a support to realize mitigation plans, susceptibility maps and other useful for the local administrators. The Persistent Scatterers were used to monitor the evolution in recent years, up to 2015. Then, for both case studies, the damage was revealed on structures and facilities by several field surveys and classified by means of five literature damage categorizations. During their application, some drawbacks and benefits of the methodologies were carried out and a new approach to improve the categorization of the damage on structures, facilities and ground surfaces was developed. This was conceived in two subsequent phases: i) a classification to use during the field campaign to quantify the severity of cracks and fractures on structures, facilities and ground surfaces; ii) an a posteriori ranking to apply on the entire structure, involving the extension of damage classes, performed by a cell-grid matrix. Furthermore, a damage recording scheme, useful for the recognition of cracks and fractures during the field surveys, was proposed. A critical comparison between the results obtained applying the different classification approaches, then followed. Buildings and facilities, for both sites, were categorized using also kinematic parameters such as velocity and maximum displacement measured along the Line Of Sight, derived by A-DInSAR, and their absolute values re-projected along the steepest local slope. Once characterized and categorized all structures and facilities of both sites of interest, a correlation between the surveyed damage classes and the deriving parameters by satellite were looked for. The investigation was carried to understand the behaviour of entire structures, subject to displacements. The first analysis was conducted on the Agnone test site where for several constructions an upper regression line between damage categories and velocity reprojected along the slope was recognized. Some outlayers were identified, mainly for low damage levels, then singularly investigated. To assess the reliability of all the structures, a matrix involving damage and velocity along the slope parameter acquired by ENVISAT and COSMO-SkyMed sensors was developed in order to obtain a classification. To validate the correlation and the reliability matrix the same procedure was applied to the Volterra site. Once asserted the validity of the relation between the velocity reprojected along the steepest slope and the classes of damage also for this area, the reliability matrix was applied on the constructions of the Volterra site. In this way, the relation between the displacement occurred during the period covered by ENVISAT and COSMO-SkyMed shows how the surveyed damage construction are related to the displacement. Some areas where damage occurred in the 2000 shows high reliability with ENVISAT recorded velocity, while others structures exhibits high reliability with COSMO-SkyMed data. The results were interesting because they highlight the fact that for some construction there is correlation between velocity of displacement of the entire structure and affecting damage; for others, instead, the high damage is related to the differential settlement and not necessarily to a high rate of displacement velocity.

Mapping aerial images from UAV

Conference Paper

Jul 2016

Theoretical Background

Chapter

Jan 2012

Benni Thiebes

A very basic but widely accepted and used definition for landslide was established by Cruden (1991) and Cruden and Varnes (1996) and defines a landslide as “the movement of a mass of rock, debris or earth down a slope”. However, the term can be confusing if the parts of the word are considered. Cruden and Varnes (1996) note that it describes all kinds of mass movements and is not limited to granular soil (as land might suggest) or a sliding movement process. The term landslide is well established in the research community and will therefore also be used in this thesis as an overarching term referring to all movement types and material properties. Further on, the term mass movement is used interchangeably with landslide.

Integrated monitoring network for the hazard assessment of slow-moving landslides at Moio della Civitella (Italy)

Conference Paper

Full-text available

Apr 2015

Aiming at a deeper comprehension of landslide geological and geotechnical model, territorial monitoring is of utmost importance. The integration of conventional and innovative monitoring techniques allows to obtain the most precise and up-to-date information at reasonable costs. This paper focuses on the case study of Moio della Civitella (Salerno Province, Italy) where, starting from 2007, an integrated monitoring network was implemented to detect the state of activity of some landslides affecting the urban centre.

Landslide analysis and early warning - Local and regional case study in the Swabian Alb, Germany

Book

Full-text available

Jan 2011

Benni Thiebes

Remote predictive mapping of aggregate deposits using lidar

Article

Full-text available

Jan 2009

Remote predictive mapping techniques have been used in the Annapolis Valley, Nova Scotia, to map surficial aggregate deposits. High-resolution digital elevation models (DEMs) have been derived from light detection and ranging (lidar) data for two study sites. The lidar surveys were conducted in the spring of 2003 and 2004, ensuring that a significant number of the pulses make it to the ground or near the ground. The glacial landforms were interpreted for each site, and sediment-depth maps were calculated. The sediment depth for the Annapolis Valley site was constrained by drill hole information and pit locations. Several potential target sites have been identified using the DEM data. The North Mountain site represents a network of eskers that rest on the North Mountain Basalt, which dips 6° toward the Bay of Fundy. Sediment depth and volume were calculated for this deposit by constructing a plane representing the bedrock surface and subtracting it from the DEM. Although the landforms on the North Mountain had been previously mapped using traditional methods, details of their morphology and extent were not well resolved. The lidar provided adequate resolution to identify several new potential aggregate deposits. Follow-up fieldwork for the Annapolis Valley site has revealed that some of the targets are comprised of sand, and others do not have enough pure sand to make them economically viable at the present time.

LIDAR validation using GIS: A case study comparison between two LIDAR collection methods

Article

Full-text available

Dec 2005

Tim L Webster

In the summer of 2000, the Annapolis Valley of Nova Scotia, Canada was selected for a high‐resolution elevation survey utilizing LIDAR (Light Detection And Ranging). Two different LIDAR systems were used to acquire data for the area. The vertical accuracy specification for the survey called for heights to be within an average of 15 cm of measured GPS heights and 95% of the data to be within 30 cm. Prior to the application of these data to geoscientific problems, extensive validation procedures were employed. High precision GPS and traditional surveys were conducted to collect height validation checkpoints. Two validation methods were developed in a GIS environment that involved comparing the checkpoints to the original LIDAR points and to an interpolated “bald earth” DEM. A systematic height error between flight lines for one of the LIDAR methods was detected that related to the calibration procedures used in the survey. This study highlights the differences between laser systems, calibration and deployment methodologies and emphasizes the necessity for independent validation data.

Flood risk mapping using LiDAR for annapolis Royal, Nova Scotia, Canada

Article

Full-text available

Sep 2010

Tim L Webster

A significant portion of the Canadian Maritime coastline has been surveyed with airborne Light Detection and Ranging (LiDAR). The purpose of these surveys has been to map the risk of flooding from storm surges and projected long-term sea‑level rise from climate change and to include projects in all three Maritime Provinces: Prince Edward Island, New Brunswick, and Nova Scotia. LiDAR provides the required details in order to map the flood inundation from 1 to 2 m storm surge events, which cause coastal flooding in many locations in this region when they occur at high tide levels. The community of Annapolis Royal, Nova Scotia, adjacent to the Bay of Fundy, has been surveyed with LiDAR and a 1 m DEM (Digital Elevation Model) was constructed for the flood inundation mapping. Validation of the LiDAR using survey grade GPS indicates a vertical accuracy better than 30 cm. A benchmark storm, known as the Groundhog Day storm (February 1–3, 1976), was used to assess the flood maps and to illustrate the effects of different sea-level rise projections based on climate change scenarios if it were to re-occur in 100 years time. Near shore bathymetry has been merged with the LiDAR and local wind observations used to model the impact of significant waves during this benchmark storm. Long-term (ca. greater than 30 years) time series of water level observations from across the Bay of Fundy in Saint John, New Brunswick, have been used to estimate return periods of water levels under present and future sea-level rise conditions. Results indicate that under current sea-level rise conditions this storm has a 66 year return period. With a modest relative sea-level (RSL) rise of 80 cm/century this decreases to 44 years and, with a possible upper limit rise of 220 cm/century, this decreases further to 22 years. Due to the uncertainty of climate change scenarios and sea-level rise, flood inundation maps have been constructed at 10 cm increments up to the 9 m contour which represents an upper flood limit estimate in 100 years, based on the highest predicted tide, plus a 2 m storm surge and a RSL of 220 cm/century.

A quality assessment of airborne laser scanner data

Article

Full-text available

Jan 2003

A Toposys-1 airborne laser scanner (ALS or LIDAR) measurement campaign was arranged in June 2000 (Kalkkinen) and another campaign with helicopter-borne TopEye laser scanner was arranged in September 2002 in southern Finland (Masala, Otaniemi). The Toposys flying altitudes were about 400 and 800 m above ground and for the TopEye, 100, 200, 400 and 550 m flying altitudes were used. Reference measurements on the ground were made with a RTK GPS and a tachymeter. Points on asphalt, grass, gravel and forest ground were measured. Height errors for different surfaces were calculated. The higher the flying altitude, the larger is the height error. All the three comparison methods (ALS mean height in the test circle, height of the nearest laser point and interpolated height) seem to give the similar results for the mean of differences (reference height - ALS height) in the same flight line. There were also quality differences between flight lines. Also height errors as a function of observation angle were determined. Observation angle had an effect on the height accuracy. A systematic error of typically 10 cm was observed due to observation angle changes. Different R-squared values (coefficient of determination in the regression analysis) were obtained for the same surface material at different flying altitudes. In this paper, the elevation accuracy of digital evelation models and original laser points is studied in different test sites, with different surface types (forest, gravel, asphalt, grass), with two different sensors (Toposys-1 and TopEye), with different flying heights, as a function of observation angle and using different kinds of means to derive the elevation from the cloud of point.

Airborne Laser/GPS Mapping of Assateague National Seashore Beach

Article

Full-text available

Jan 2000
PHOTOGRAMM ENG REM S

Results are presented from topographic surveys of the Assateague Island National Seashore using an airborne scanning laser altimeter and kinematic Global Positioning System (GPS) technology. The instrument used was the Airborne Topographic Mapper (ATM), developed by the NASA Arctic Ice Mapping (AIM) group from the Goddard Space Flight Center's Wallops Flight Facility. In November, 1995, and again in May, 1996, these topographic surveys were flown as a functionality check prior to conducting missions to measure the elevation of extensive sections of the Greenland Ice Sheet as part of NASA's Global Climate Change program. Differences between overlapping portions of both surveys are compared for quality control. An independent assessment of the accuracy of the ATM survey is provided by comparison to surface surveys which were conducted using standard techniques. The goal of these projects is to make these measurements to an accuracy of ± 10 cm. Differences between the fall 1995 and 1996 surveys provides an assessment of net changes in the beach morphology over an annual cycle.

Accuracy of Airborne LIDAR-Derived Elevation: Empirical Assessment and Error Budget

Article

Full-text available

Mar 2004
PHOTOGRAMM ENG REM S

As part of a countywide large-scale mapping effort for Richland County, South Carolina, an accuracy assessment of a recently acquired lidar-derived data set was conducted. Airborne lidar (2-m nominal posting) was collected at a flying height of 1207 meters above ground level (AGL) using an Optech ALTM (Airborne Laser Terrain Mapper) 1210 system. Unique to this study are the reference point elevations. Rather than using an interpolation approach for gathering observed elevations at reference points, the x-y coordinates of lidar points were located in the field and these elevations were surveyed. Using both total-station-based and rapid-static GPS techniques, observed vertical heights were measured at each reference lidar posting. The variability of vertical accuracy was evaluated for six land-cover categories. Root-meansquared error (RMSE) values ranged from a low of 17 to 19 cm (pavement, low grass, and evergreen forests) to a high of 26 cm (deciduous forests). The unique error assessment of lidar postings also allowed for the creation of an error budget model. The observed lidar elevation error was decomposed into errors from lidar system measurements, horizontal displacement, interpolation error, and surveyor error. A crossvalidation approach was used to assess the observed interpolated lidar elevation error for each field-verified reference point. In order of decreasing importance, the lidar system measurements were the dominant source of error followed by interpolation error, horizontal displacement error, and surveyor error. Observed elevation error in steeper slopes (e.g., 25º) was estimated to be twice as large as those on low slopes (e.g., 1.5º).

Using topographic lidar to map flood risk from storm-surge events in Charlottetown, Prince Edward Island, Canada

Article

Full-text available

Feb 2004

As part of a recent project to determine coastal impacts of climate change and sea-level rise on Prince Edward Island (PEI), airborne scanning laser altimetry (lidar) was employed to acquire high-resolution digital elevation models (DEMs) and other landscape information. The study area included both the Charlottetown urban area and an extensive portion of the rural North Shore of PEI. Problems with the lidar data included data gaps and incorrect classification of "ground" and "non-ground" laser hits along the waterfront. Accurate representation of wharves and other waterfront features in the DEM was achieved by combining "ground" and "non-ground" data. The importance of calibration and validation in lidar data acquisition and interpretation was demonstrated by three independent validation exercises that uncovered and adjusted for a vertical offset attributed to calibration problems. The ground DEM was adjusted to hydrographic chart datum and used to model flood extent at three storm-surge water levels, one observed in the record storm of 21 January 2000 and two higher levels representing flood scenarios under rising sea level. Flood modelling was executed in a geographic information system (GIS) on the gridded ground DEM. The resulting binary grids were vectorized along the flooding limit. Low-lying areas isolated from free exchange with the harbour were excluded from the flood area. Vectors depicting the storm-surge water lines for the three flood scenarios were implemented on the geographic information system (GIS) in the city planning department and overlain on property boundary and assessment layers. This study demonstrated that validated DEMs derived from airborne lidar data are efficient and adequate tools for mapping flood risk hazard zones in coastal communities.

An Evaluation of Lidar-derived Elevation and Terrain Slope in Leaf-off Conditions

Article

Full-text available

Jul 2005
PHOTOGRAMM ENG REM S

The effects of land cover and surface slope on lidar-derived elevation data were examined for a watershed in the pied- mont of North Carolina. Lidar data were collected over the study area in a winter (leaf-off) overflight. Survey-grade elevation points (1,225) for six different land cover classes were used as reference points. Root mean squared error (RMSE) for land cover classes ranged from 14.5 cm to 36.1 cm. Land cover with taller canopy vegetation exhibited the largest errors. The largest mean error (36.1 cm RMSE) was in the scrub-shrub cover class. Over the small slope range (0° to 10°) in this study area, there was little evidence for an increase in elevation error with increased slopes. However, for low grass land cover, elevation errors do increase in a consistent manner with increasing slope. Slope errors increased with increasing surface slope, under-predicting true slope on surface slopes � 2°. On average, the lidar- derived elevation under-predicted true elevation regardless of land cover category. The under-prediction was significant, and ranged up to � 23.6 cm under pine land cover.

Vegetation class-dependant errors in LiDAR ground elevation and canopy height estimates in a Boreal wetland environment

Article

Full-text available

Apr 2005

An airborne scanning light detection and ranging (lidar) survey using a discrete pulse return airborne laser terrain mapper (ALTM) was conducted over the Utikuma boreal wetland area of northern Alberta in August 2002. These data were analysed to quantify vegetation class dependent errors in lidar ground surface elevation and vegetation canopy surface height. The sensitivity of lidar-derived land-cover frictional parameters to these height errors was also investigated. Aquatic vegetation was associated with the largest error in lidar ground surface definition (+0.15 m, SD = 0.22, probability of no difference in height P < 0.01), likely a result of saturated ground conditions. The largest absolute errors in lidar canopy surface height were associated with tall vegetation classes; however, the largest relative errors were associated with low shrub (63%, -0.52 m, P < 0.01) and aquatic vegetation (54%, -0.24 m, P < 0.01) classes. The openness and orientation of vegetation foliage (i.e., minimal projection of horizontal area) were thought to enhance laser pulse canopy surface penetration in these two classes. Raster canopy height models (CHMs) underestimated field heights by between 3% (aspens and black spruce) and 64% (aquatic vegetation). Lidar canopy surface height errors led to hydraulic Darcy-Weisbach friction factor underestimates of 10%-49% for short (

Analysis and implementation of a laser strip adjustment model

Article

Full-text available

Jan 2003

Sagi Filin

The objectives of a strip laser adjustment are simple to define, namely improving the accuracy of laser data and creating a seamless dataset. Achieving these objectives is however dicult. Complex data acquisition systems and numerous error sources make the formulation of a strip adjustment model a complex problem. Diculties in manually processing the data and limited information consisting only of the laser point coordinates, but not of the system measurements, imply that a strip adjustment is more then just an analytical model. This paper elaborates on both aspects of the problem. The proposed model is presented first and is followed by a discussion about implementation concerns. The model is system driven and is based on modeling the actual errors in the system. Automatic selection of tie regions in accordance with the proposed model and the implementation of the system driven model when only laser points are provided are two implementation concerns that are discussed in some level of detail. The paper concludes with discussion and analysis.

LIDAR validation using GIS: A case study comparison between two LIDAR collection methods

Article

Full-text available

Dec 2005

Tim L Webster

Least-Squares Matching with airborne laserscanning data in a TIN structure

Article

Full-text available

Jan 2000

Hans-Gerd Maas

A number of tasks in airborne laserscanning require the establishment of correspondences between point data from neighbouring strips, or referencing between point clouds and object models. These tasks may be solved by interpolating laserscanner data, which are usually irregularly distributed 2 1 / 2 -D points, to a regular grid and applying standard photo-grammetric matching techniques. Instead, the paper presents a formulation of least squares matching based on the original data points in a triangulated irregular network structure, thus avoiding degrading effects caused by the interpo-lation. The technique determines shifts in all three coordinate directions together with their covariance matrix. It can be shown that applying matching techniques to laserscanner data causes large systematic errors of the shift parameters in the case of partial occlusions. The presented formulation on the basis of a TIN structure allows for manifold extensions to solve this problem. The technique and a number of extensions have been implemented and applied to the measurement of strip errors in an airborne laser scanner dataset with moderate point density, consisting of 20 strips including crossing strips. The paper shows the results from this test, discusses the advantages of the presented technique and the limitations of matching techniques applied to laserscanner data. Special attention has to be paid to problems caused by height discontinuities in the data and by the fact that the design matrix in least squares matching is derived from observations with stochastic properties. The latter leads to precision figures that are usually much too optimistic. A detailed analysis of the design matrix and extensive testing lead to better funded precision figures for the standard deviation of the obtained shift parameters. These are in the order of one centimeter in height direction and one decimeter in horizontal direction, corresponding to about 1 / 20 th of the average point spacing.

Fault scarp detection beneath dense vegetation cover: Airborne lidar mapping of the Seattle fault zone, Bainbridge Island, Washington State

Article

Full-text available

Apr 2000

The emergence of a commercial airborne laser mapping industry, inspired by NASA technology research and development, is paying major dividends in an assessment of earthquake hazards in the Puget Lowland of Washington State. Geophysical observations and historical seismicity indicate the presence of active upper-crustal faults in the Puget Lowland, placing the major population centers of Seattle and Tacoma at significant risk. However, until recently the surface trace of these faults had never been identified, neither on the ground nor from remote sensing, due to cover by the dense vegetation of the Pacific Northwest temperate rainforests and extremely thick Pleistocene glacial deposits. A pilot lidar mapping project of Bainbridge Island in the Puget Sound, contracted by the Kitsap Public Utility District (KPUD) and conducted by Airborne Laser Mapping in late 1996, spectacularly revealed geomorphic features associated with fault strands within the Seattle fault zone. The features include a previously unrecognized fault scarp, an uplifted marine wave-cut platform, and tilted sedimentary strata. The United States Geologic Survey (USGS) is now conducting trenching studies across the fault scarp to establish ages, displacements, and recurrence intervals of recent earthquakes on this active fault. The success of this pilot study has inspired the formation of a consortium of federal and local organizations to extend this work to a 2350 square kilometer (580,000 acre) region of the Puget Lowland, covering nearly the entire extent (~85 km) of the Seattle fault. The consortium includes NASA, the USGS, and four local groups consisting of KPUD, Kitsap County, the City of Seattle, and the Puget Sound Regional Council (PSRC). The consortium has selected Terrapoint, a commercial lidar mapping vendor, to acquire the data. Terrapoint is a commercial spin-off from the Houston Advanced Research Center (HARC). HARC was funded by the NASA Technology Utilization Program to commercialize the Airborne Terrain Mapping technology developed by Bill Krabill of NASA's Arctic Ice Mapping program.

Strip adjustment of LIDAR data

Article

Full-text available

Oct 2003

LIght Detection And Ranging (LIDAR) is a technique, which allows for measuring a huge amount of object point coordinates with accuracies up to some centimeters in short time. Their conversion into a highly accurate Digital Terrain Model (DTM) requires a careful handling of the single processing steps, from the flight planning until the manual revision of the generated DTM, considering the different error sources. In addition it must be ensured, that the LIDAR system maintains correctly calibrated during all the flight sessions. This paper describes a simple adjustment approach, which compensates for the mayor part of systematic vertical errors, mainly originating from the GPS, and it allows for almost automatic processing also of huge amounts of laser data. The approach was developed and applied in the framework of a real project, whose objective was to generate a highly accurate DTM of the Eastern Ter river. The obtained results of two selected sub-blocks are presented, which are also verified by independent check points.

Estimating intrinsic accuracy of airborne laser data with local 3D-offsets

Article

Full-text available

Airborne laser systems provide a three-dimensional (3D) perception of the Earth's topography with clouds of points. Whereas the technique ensures a high theoritical quality, one can observe discrepancies in certain areas. This situation may be of importance in case of joint sensor application, like merging airborne laser scanner with photogrammetry. The first step of a fusion process is to define a common reference frame so that a global geometric coherence should be extracted. This article describes a methodology for matching a single laser strip with a photogrammetric derived Digital Elevation Model (DEM), and as a result estimating intra-strip errors. It is based on calculating local linear deformations with a tri-dimensionnal accumulator (translation space). We show that searching for local discrepancy is equivalent to compute the maximum of the accumulator. 2D and 3D simulated problems are discussed in details and solved over known transformed data set. Results on real data show a significant improvement when applying retrieved local translations to laser points. After correction, both data sets tend to be expressed in the same reference frame. The accurate registration is then ensured.

Greenland Ice Sheet: High-Elevation Balance and Peripheral Thinning

Article

Full-text available

Aug 2000
SCIENCE

Aircraft laser-altimeter surveys over northern Greenland in 1994 and 1999 have been coupled with previously reported data from southern Greenland to analyze the recent mass-balance of the Greenland Ice Sheet. Above 2000 meters elevation, the ice sheet is in balance on average but has some regions of local thickening or thinning. Thinning predominates at lower elevations, with rates exceeding 1 meter per year close to the coast. Interpolation of our results between flight lines indicates a net loss of about 51 cubic kilometers of ice per year from the entire ice sheet, sufficient to raise sea level by 0.13 millimeter per year-approximately 7% of the observed rise.

Capture Andevaluation of Airborne Laser Scanner Data

Article

Full-text available

Apr 2001

The development of laser sensors for the direct measurement of the terrain surface resulted in airborne systems allowing an area covering 3D data capture which are already in commercial use. By the integration of the laser scanner with sensors for the absolute orientation of the laser scanner at the time of measurement, like the NAVSTAR Global Positioning System (GPS) for the positioning task and an Inertial System (INS) for the orientation task, a powerful sensor system for the direct acquisition of 3D terrain data from an aircraft is available. Using scanning laser sensors as the main component of the laser sensor system, the points on the terrain surface can be measured dense and well-distributed.

Announcement of the Proposed ASPRS Binary LIDAR Data File Format Standard

Article

K. Schuckman

About the calibration of lidar sensors

Article

Jan 2003

R. Katzenbeisser

Adjustment of laser scanner data for correction of orientation errors

Article

Jan 2000

H. Burman

On the adjustment of overlapping strips of laser altimeter height data

Article

Jan 2000

About the calibration of LiDAR sensors

Article

Jan 2003

R. Katzenbeisser

Basis and methods of NASA Airborne Topographic Mapper lidar surveys for coastal studies

Article

Dec 2002
J COASTAL RES

This paper provides an overview of the basic principles of airborne laser altimetry for surveys of coastal topography, and describes the methods used in the acquisition and processing of NASA Airborne Topographic Mapper (ATM) surveys that cover much of the conterminous US coastline. This form of remote sensing, also known as "topographic lidar", has undergone extremely rapid development during the last two decades, and has the potential to contribute within a wide range of coastal scientific investigations. Various airborne laser surveying (ALS) applications that are relevant to coastal studies are being pursued by researchers in a range of Earth science disciplines. Examples include the mapping of "bald earth" land surfaces below even moderately dense vegetation in studies of geologic framework and hydrology, and determination of the vegetation canopy structure, a key variable in mapping wildlife habitats. ALS has also proven to be an excellent method for the regional mapping of geomorphic change along barrier island beaches and other sandy coasts due to storms or long-term sedimentary processes. Coastal scientists are adopting ALS as a basic method in the study of an array of additional coastal topics. ALS can provide useful information in the analysis of shoreline change, the prediction and assessment of landslides along seacliffs and headlands, examination of subsidence causing coastal land loss, and in predicting storm surge and tsunami inundation.

Estimation of shoreline position and change using airborne topographic LIDAR data

Article

Jun 2002
J COASTAL RES

A method has been developed for estimating shoreline position from airborne scanning laser data. This technique allows rapid estimation of objective, GPS-based shoreline positions over hundreds of kilometers of coast, essential for the assessment of large-scale coastal behavior. Shoreline position, defined as the cross-shore position of a vertical shoreline datum, is found by fitting a function to cross-shore profiles of laser altimetry data located in a vertical range around the datum and then evaluating the function at the specified datum. Error bars on horizontal position are directly calculated as the 95% confidence interval on the mean value based on the Student's t distribution of the errors of the regression. The technique was tested using lidar data collected with NASA's Airborne Topographic Mapper (ATM) in September 1997 on the Outer Banks of North Carolina. Estimated lidar-based shoreline position was compared to shoreline position as measured by a ground-based GPS vehicle survey system. The two methods agreed closely with a root mean square difference of 2.9 m. The mean 95% confidence interval for shoreline position was ± 1.4 m. The technique has been applied to a study of shoreline change on Assateague Island, Maryland/Virginia, where three ATM data sets were used to assess the statistics of large-scale shoreline change caused by a major 'northeaster' winter storm. The accuracy of both the lidar system and the technique described provides measures of shoreline position and change that are ideal for studying storm-scale variability over large spatial scales.

Recovery of Systematic Biases in Laser Altimetry Data Using Natural Surfaces

Article

Nov 2003
PHOTOGRAMM ENG REM S

Sagi Filin

The accuracy of lidar systems and the removal of systematic errors have received growing attention in recent years. The level of accuracy and the additional processing that is needed for making the raw data ready to use are affected directly by the systematic errors in the laser data. It is evident that calibration of the lidar system, both laboratory and in-flight, are mandatory to alleviate these deficiencies. This paper presents an error recovery model that is based on modeling the system errors and on defining adequate control information. The association of the observations and control information, and configurations that enhance the reliability of the recovered parameters, are also studied here in detail. The application of the model is demonstrated on two of the main error sources in the system, the mounting and the range bias.

Airborne laser study quantifies El Ni˜o-induced Coastal Change

Article

Jan 1999
Eos Trans. AGU

Winter storms during the 1997–1998 El Niño caused extensive changes to the beaches and cliffs of the west coast of the United States, a NASA-NOAA-USGS investigation using a scanning airborne laser has found. For example, near Pacifica in central California, the cliff eroded locally as much as 10–13 m landward during the El Niño winter, at least 40 times the long term average erosion rate. However, only several hundred meters away the cliff was stable. This variability in cliff response may be related to differences in local beach changes where an accreting beach protected part of the cliff and an eroding beach exposed another part to attack by waves.

High-Resolution Lidar Topography of the Puget Lowland, Washington —A Bonanza for Earth Science

Article

Jun 2003

More than 10,000 km2 of high-resolution, public-domain topography acquired by the Puget Sound Lidar Consortium is revolutionizing investigations of active faulting, continental glaciation, landslides, and surficial processes in the seismically active Puget Lowland. The Lowland-the population and economic center of the Pacific Northwest-presents special problems for hazards investigations, with its young glacial topography, dense forest cover, and urbanization. Lidar mapping during leaf-off conditions has led to a detailed digital model of the landscape beneath the forest canopy. The surface thus revealed contains a rich and diverse record of previously unknown surface-rupturing faults, deep-seated landslides, uplifted Holocene and Pleistocene beaches, and subglacial and periglacial features. More than half a dozen suspected postglacial fault scarps have been identified to date. Five scarps that have been trenched show evidence of large, Holocene, surface-rupturing earthquakes.

Errors and Accuracy Estimates of Laser Data Acquired by Various Laser Scanning Systems for Topographic Applications

Article

Oct 1998
ISPRS J PHOTOGRAMM

The Survey Department of Rijkswaterstaat in The Netherlands makes extensive use of laser scanning for topographic measurements. An inventory of sources of errors indicates that errors may vary from 5 to 200 cm. The experience shows that errors related to the laser instrument, GPS and INS may frequently occur, resulting in local distortions, and planimetric and height shifts. Moreover, the results indicate that for flat terrain, having corrected for gross errors, an offset of less than 10 cm can often be obtained and standard deviations are generally well within 15 cm. For hilly and flat terrain densely covered by vegetation, accuracy estimates do not generally fulfil those required by Rijkswaterstaat. However, the use of an adequate strategy for data collection and processing will, to a great extent, improve the accuracy and fidelity of the results. Thus, research should be devoted to the design of appropriate strategies for data collection and processing.

Accuracy of Airborne Laser Altimetry Over the Greenland Ice Sheet

Article

May 1995

During September 1991, April 1992 and June/July 1993, a NASA P–3 aircraft, equipped with a scanning laser altimeter, flew numerous transects of the Greenland ice sheet. The aeroplane location was measured precisely using dilTerential Global Positioning System (GPS) surveying techniques, allowing all altimetry data to be converted into measurements of ice-surface elevation relative to the Earth ellipsoid. Results from flight data indicate that icc-surface elevations can be reliably measured to an accuracy of 20cm (and possibly to s lOcm) over baselines of more than seven hundred kilometres.

Methods for Measuring Height and Planimetry Discrepancies in Airborne Laserscanner Data

Article

Sep 2002
PHOTOGRAMM ENG REM S

Hans-Gerd Maas

tems is limited by the laser power and receiver sensitivity. Airborne laserscanning (or lidar) has become a very important Together with a narrow opening angle for minimizing occlu- technique for the acquisition of digital terrain model data. sions, this results in laserscanner datasets consisting of many Beyond this, the technique is increasingly being used for the parallel strips with a width of several hundred meters in most acquisition of point clouds for 3D modeling of a wide range of cases. objects, such as buildings, vegetation, or electrical power lines. Over the last few years, airborne laserscanning has gained As an active technique, airborne laserscanning offers a high a lot of attention and has become a leading technique for the reliability even over terrain with poor image contrast. The acquisition of digital terrain model data. Its advantages are its precision of the technique is often specified to be on the order fast and efficient manner of data acquisition as well as its high of one to two decimeters. By reason of its primary use in digital reliability and precision potential. Since the early nineties, air- terrain modeling, examinations of the precision potential of borne laserscanninghas been usedfor special taskssuch as,for airborne laserscanning have so far been concentrated on the example, beach erosion monitoring. Meanwhile, it is replacing height precision. With the use of the technique for general 3D conventional stereo-imaging-based photogrammetric tech- reconstruction tasks and the increasing resolution of niques andis acceptedas a generaltool for digitalterrain model laserscanner systems, the planimetric precision of data acquisition. The Netherlands were the first country to laserscanner point clouds becomes an important issue. generate a nationwide digital terrain model purely based on In addition to errors in the laser distance meter and the laserscanner data (e.g., Wouters and Bollweg, 1998). deflecting mirror system, the error budget of airborne While early systems offered data rates on the order of 2 to 7 laserscanning instruments is strongly influenced by the GPS/ kHz (i.e., 2000 to 7000 3D surface points per second), modern INS systems used for sensor pose (position and orientation) systems come with data rates of 25 up to 83 kHz. This gain in determination. Errors of these systems often lead to the temporal resolution has not only increased the efficiency of deformation of laserscanner data strips and may become data acquisition, but has also opened a whole range of new evident as discrepancies in the overlap region between application fields to airborne laserscanning. It broadens the neighboring strips in a block of laserscanner data. The paper scope of the technique beyond the pure acquisition of digital presents least-squares matching implemented on a TIN terrain models to a more general tool for the acquisition of point structure as a general tool for the determination of laser- clouds for 3D modeling of a wide range of objects. High resolu- scanner strip discrepancies in all three coordinate directions, tion laserscanner data have proven to be a valuable source for using both height and reflectance data. Practical problems of the automatic generation of 3D building models (Haala and applying matching techniques to 2.5D laserscanner point Brenner, 1997; Maas and Vosselman, 1999). Further examples clouds are discussed and solved, and the success of the of new application fields are the determination of forest stand technique is shown on the basis of several datasets. Applying parameters and corridor mapping. least-squares matching techniques to dense laserscanner data in a TIN structure, strip discrepancies can be determined with The precision potential of the technique is often specified as 1 to 2 decimeters. Due to the primary application field in the centimeter precision for the height coordinate and decimeter precision for the planimetric coordinates.

Calculation of Ice Velocities in the Jakobshavn Isbrae Area Using Airborne Laser Altimetry

Article

Feb 1999
REMOTE SENS ENVIRON

The ability to measure velocities of fast-moving glaciers is essential to the understanding and interpretation of their dynamics and related processes. This is especially important in the Jakobshavn drainage basin of the Greenland ice sheet, where a significant portion of the ice sheet mass loss occurs and the iceberg calving rate is high. In this article, we present a method for using airborne laser altimetry data to determine surface velocities in portions of the Jakobshavn drainage basin that have distinct elevation features. By examining correlations between repeat elevation surveys, the motion of these features, the most distinct of which are crevasses, is tracked. Results show that for areas with a standard deviation in elevation in excess of 1 m, displacement of features can be tracked to a precision of 1–2 m, and the corresponding velocities can be retrieved. The maximum velocity of the Jakobshavn Isbrae, at its calving front, is found to be nearly 7 km yr−1. Ice stream boundaries and flow patterns can also be observed in the derived velocity data.

Practical methods for the verification of countrywide terrain and surface models

Article

Jan 2003

The Swiss Federal Office of Topography is leading a project for the determination of correct agricultural surfaces. As a part of this project, a Digital Terrain Model and a Digital Surface Model is being generated using airborne laser scanning methods. These two models must achieve a height accuracy of 50cm and a mean density of 1 point per m 2 . One of the main tasks of swisstopo is to con-trol the quality of the two models. To fulfil this task, a combined strategy using global and local control techniques has been estab-lished. This paper will focus on the philosophy and the tools swisstopo uses for the verification of a countrywide produced elevation model. Our investigations showed that quality control is mandatory when generating models by means of airborne laser scanning.

Airborne laser scanning - An introduction and overview

Article

Jul 1999
ISPRS J PHOTOGRAMM

This tutorial paper gives an introduction and overview of various topics related to airborne laser scanning (ALS) as used to measure range to and reflectance of objects on the earth surface. After a short introduction, the basic principles of laser, the two main classes, i.e., pulse and continuous-wave lasers, and relations with respect to time-of-flight, range, resolution, and precision are presented. The main laser components and the role of the laser wavelength, including eye safety considerations, are explained. Different scanning mechanisms and the integration of laser with GPS and INS for position and orientation determination are presented. The data processing chain for producing digital terrain and surface models is outlined. Finally, a short overview of applications is given.

Determination of Terrain Models in Wooded Areas with Airborne Laser Scanner Data

Article

Aug 1998
ISPRS J PHOTOGRAMM

Large-scale terrain measurement in wooded areas was an unsolved problem up to now. Laser scanning solves this problem to a large extent. In this article, the characteristics of laser scanning will be compared to photogrammetry with reference to a big pilot project. Laser scanning supplies data with a skew distribution of errors because a portion of the supplied points is not on the terrain but on the treetops. Thus, the usual interpolation and filtering has to be adapted to this new data type. We will report on the implementation of this new method. The results are in accordance with the expectations. The geomorphologic quality of the contours, computed from a terrain model derived from laser scanning, needs to be improved. Solutions are still to be found.

An evaluation of LiDAR- and IFSAR-derived digital elevation models in leaf-on conditions with USGS level 1 and level 2 DEMs

Article

Feb 2003
REMOTE SENS ENVIRON

An assessment of four different remote sensing based methods for deriving digital elevation models (DEMs) was conducted in a flood-prone watershed in North Carolina. New airborne LIDAR (light detecting and ranging) and IFSAR (interferometric synthetic aperture radar (SAR)) data were collected and corresponding DEMs created. These new sources were compared to two methods: Gestalt Photomapper (GPM) and contour-to-grid, used by the U.S. Geological Survey (USGS) for creating DEMs. Survey-grade points (1470) for five different land cover classes were used as reference points. One unique aspect of this study was the LIDAR and IFSAR data were collected during leaf-on conditions. Analyses of absolute elevation accuracy and terrain slope were conducted. The LIDAR- and contour-to-grid derived DEMs exhibited the highest overall absolute elevation accuracies. Elevation accuracy was found to vary with land cover categories. Elevation accuracy also decreased with increasing slopes—but only for the scrub/shrub land cover category. Appreciable terrain slope errors for the reference points were found with all methods.

An evaluation of lidar-derived elevation and terrain slope in leaf-off conditions SensingAnnual Conference Vegetation class dependent errors in lidar ground elevation and canopy height estimates in a boreal wetland environment

817-823

M E Hodgson
J Jensen
G Raber
J Tullis
B A Davis
G Thompson
K Article Schuckman
T L Webster
G Dias

Hodgson, M.E., Jensen, J., Raber, G., Tullis, J., Davis, B.A., Thompson, G., Schuckman, K., 2005. An evaluation of lidar-derived elevation and terrain slope in leaf-off conditions. Photogrammetric Engineering and Remote Sensing 71 (7), 817–823. SensingAnnual Conference, ARTICLE IN PRESS T.L. Webster, G. Dias / Computers & Geosciences 32 (2006) 713–726 725 rHopkinson, C., Chasmer, L.E., Sass, G., Creed, I.F., Sitar, M., Kalbfleisch, W., Treitz, P., 2005. Vegetation class dependent errors in lidar ground elevation and canopy height estimates in a boreal wetland environment. Canadian Journal of Remote Sensing 31 (2), 191–206

Commercial implications of topographic terrain mapping using scanning airborne laser radar

Jan 1997
327

Flood

Flood, M., Gutelius, B., 1997. Commercial implications of topographic terrain mapping using scanning airborne laser radar. Photogrammetric Engineering and Remote Sensing 4, 327–366.

Quality improvement of laser altimetry DEM's 3-D Reconstruction from Airborne Laserscanner and InSAR Data. Institute of Photo-grammetry and Remote Sensing, GITC, The Netherlands

Jan 2003
51-58

S O Elberink
G Brand
R Brugelmann

Elberink, S.O., Brand, G., Brugelmann, R., 2003. Quality improvement of laser altimetry DEM's. In: Maas, H.-G., Vosselman, G., Streilein, A. (Eds.), 3-D Reconstruction from Airborne Laserscanner and InSAR Data. Institute of Photo-grammetry and Remote Sensing, GITC, The Netherlands, pp. 51–58.

Accuracy study of airborne laser altimetry data

T Schenk
S Seo
B Csatho

Schenk, T., Seo, S., Csatho, B., 2001. Accuracy study of airborne laser altimetry data. In: Proceedings of the International Society of Photogrammetry and Remote Sensing Workshop, Annapolis Maryland. International Archives of Photogram-metry, Remote Sensing and Spatial Information Sciences, vol. XXXIV-3/W4, pp. 113–118.

Recovery of systematic biases in laser altimeters using natural surfaces In: Proceedings of the International Society of Photogrammetry and Remote Sensing workshop, Annapolis Maryland. International Archives of Photogram-metry

Jan 2001
85-91

S Filin

Filin, S., 2001. Recovery of systematic biases in laser altimeters using natural surfaces. In: Proceedings of the International Society of Photogrammetry and Remote Sensing workshop, Annapolis Maryland. International Archives of Photogram-metry, Remote Sensing and Spatial Information Sciences, vol. XXXIV-3/W4, pp. 85–91.

LIDAR data quality control and system calibration using overlapping flight lines in commer-cial environment. In: Proceedings of the American Society of Photogrammetry and Remote Sensing Annual Conference Least-squares matching with airborne laserscanning data in a TIN structure

Jan 2000
548-555

D Latypov
E Zosse

Latypov, D., Zosse, E., 2002. LIDAR data quality control and system calibration using overlapping flight lines in commer-cial environment. In: Proceedings of the American Society of Photogrammetry and Remote Sensing Annual Conference, Washington, DC, p. 13. Maas, H.G., 2000. Least-squares matching with airborne laserscanning data in a TIN structure. International Archives of Photogrammetric Engineering and Remote Sensing 33 (B3/1), 548–555.

Practical methods for the verification of countrywide terrain and surface models 3-D Reconstruction from Airborne Laserscanner and InSAR Data

Jan 2003
14-19

R Artuso
S Bovet
A Streilen

Artuso, R., Bovet, S., Streilen, A., 2003. Practical methods for the verification of countrywide terrain and surface models. In: Maas, H.-G., Vosselman, G., Streilein, A. (Eds.), 3-D Reconstruction from Airborne Laserscanner and InSAR Data. Institute of Photogrammetry and Remote Sensing, GITC, The Netherlands, pp. 14–19.

Airborne imaging, digital elevation models and flood maps Coastal Impacts of Climate Change and Sea-level Rise on Prince Edward Island. Geological Survey of Canada Open File 4261

Jan 2002
1-36

T L Webster
D L Forbes
S Dickie
R Colville
G S Parkes

Webster, T.L., Forbes, D.L., Dickie, S., Colville, R., Parkes, G.S., 2002. Airborne imaging, digital elevation models and flood maps. In: Forbes, D.L., Shaw, R.W. (Eds.), Coastal Impacts of Climate Change and Sea-level Rise on Prince Edward Island. Geological Survey of Canada Open File 4261, Supporting Document 8, pp. 1–36 (on CD-ROM).

On the calibration of LIDAR sensors 3-D Reconstruction from Airborne Laserscanner and InSAR Data

Jan 2003
59-64

R Katzenbeisser
H.-G Maas
G Vosselman
A Streilein

Katzenbeisser, R., 2003. On the calibration of LIDAR sensors. In: Maas, H.-G., Vosselman, G., Streilein, A. (Eds.), 3-D Reconstruction from Airborne Laserscanner and InSAR Data. Institute of Photogrammetry and Remote Sensing, GITC, The Netherlands, pp. 59–64.

LIDAR data quality control and system calibration using overlapping flight lines in commercial environment

D Latypov
E Zosse

Latypov, D., Zosse, E., 2002. LIDAR data quality control and system calibration using overlapping flight lines in commercial environment. In: Proceedings of the American Society of Photogrammetry and Remote Sensing Annual Conference, Washington, DC, p. 13.

Quality improvement of laser altimetry DEM's