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Norbert Pfeifer

Norbert Pfeifer
TU Wien | TU Wien · Chair of Geodesy and Geoinformation

About

374
Publications
111,117
Reads
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10,773
Citations
Additional affiliations
October 2006 - present
TU Wien
February 2006 - September 2006
University of Innsbruck
February 2003 - January 2006

Publications

Publications (374)
Poster
Full-text available
Graffiti are a short-lived and polarising form of cultural heritage. The graffiti-focused research project INDIGO, funded by ÖAW, documents and digitally preserves (almost) every graffito created along Vienna’s Donaukanal, one of the world’s largest graffiti hotspots. A central aim of INDIGO is the creation of a georeferenced orthophoto for each gr...
Presentation
Full-text available
This presentation was given in addition to a poster that was presented at the same conference and a paper under the same name.
Poster
Full-text available
A point-based level-set approach for the extraction of 3D entities from point clouds — application in geomorphological context. This poster come as an addition to the presentation given under the same name.
Presentation
Full-text available
Extraction of geomorphological entities from unstructured point clouds -- a three-dimensional level-set-based approach
Presentation
Full-text available
Alpine rivers have experienced considerable changes in channel morphology over the last century. The main problem of current studies is the lack of information over a longer period. In order to reliably assess the magnitude of the channel change processes and/or their frequencies due to recent climate change, the investigation period needs to be ex...
Presentation
Full-text available
This presentation was given by Benjamin Wild during Session E of the goINDIGO 2022 international graffiti symposium. Graffiti and street art are unique forms of cultural heritage which have not yet received the scientific attention they deserve. The potential of graffiti research to answer a variety of social and cultural research questions is und...
Article
Full-text available
The number of high and very high resolution (VHR) optical satellite sensors, as well as the number of medium resolution satellites is continuously growing. However, not all high-resolution optical satellite imaging cameras have a sufficient and stable calibration in time. Due to their high agility in rotation, a quick change in viewing direction ca...
Book
Full-text available
This is the book of abstracts created for the goINDIGO 2022 international graffiti symposium organised in the framework of the academic project INDIGO.
Preprint
A key aspect of nature conservation is knowledge of which aspects of nature to conserve or restore to favor the characteristic diversity of plants in a given area. Here, we used a large plant dataset with > 40.000 plots combined with airborne laser scanning (lidar) data to reveal the local characteristics of habitats having a high plant dark divers...
Article
Zusammenfassung Der vorliegende Beitrag beschreibt die Konzeption und die methodischen Schritte des Projekts HORA 3.0, in dem Hochwasserrisikoflächen für ganz Österreich berechnet wurden. Die Analyseschritte umfassen: Qualitätskontrolle und Korrektur des Gewässernetzes und der Einzugsgebietsgrenzen; Berechnung der Abflussscheitel und Frachten gegeb...
Presentation
Full-text available
This presentation was given by Benjamin Wild at the 3D-ARCH conference in Mantova (Italy) and won the best paper award
Article
Full-text available
Graffiti is a short-lived form of heritage balancing between tangible and intangible, offensive and pleasant. Graffiti makes people laugh, wonder, angry, think. These conflicting traits are all present along Vienna's Donaukanal (Eng. Danube Canal), a recreational hotspot – located in the city's heart – famous for its endless display of graffiti. Th...
Article
Full-text available
The convergence diameter of shield tunnels is detected by ellipse fitting or local curve fitting to cross-section points. However, the tunnel section, which is extruded by an external force, has an irregular elliptical shape, and the waist of the tunnel is often blocked by accessories, resulting in data loss. This study proposes a convergence diame...
Article
Full-text available
3D modelling of urban areas is an attractive and active research topic, as 3D digital models of cities are becoming increasingly common for urban management as a consequence of the constantly growing number of people living in cities. Viewed as a digital representation of the Earth’s surface, an urban area modeled in 3D includes objects such as bui...
Article
Full-text available
Permafrost is being degraded worldwide due to the change in external forcing caused by climate change. This has also been shown to affect the morphodynamics of active rock glaciers. We studied these changes, depending on the analysis, on nine or eight active rock glaciers, respectively, with different characteristics in multiple epochs between 1953...
Article
Full-text available
Timber assortments are some of the most important goods provided by forests worldwide. To quantify the amount and type of timber assortment is strongly important for socio-economic purposes, but also for accurate assessment of the carbon stored in the forest ecosystems, regardless of their main function. Terrestrial laser scanning (TLS) became a pr...
Article
Full-text available
Increasing river floods and infrastructure development in many parts of the world have created an urgent need for accurate high-resolution flood hazard mapping for more efficient flood risk management. Mapping accuracy hinges on the quality of the underlying Digital Terrain Model (DTM) and other spatial datasets. This article presents a processing...
Article
Terrain classification involves essential tasks in geomorphology, landscape investigation, regional planning, and hazard prediction. Most existing methods are based on a simple thresholding approach. However, such an approach is limited in terms of accuracy and robustness, especially for large-scale tasks. To overcome this limitation, this article...
Article
Full-text available
Green areas play an important role within urban agglomerations due to their impact on local climate and their recreation function. For detailed monitoring, frameworks like the flora fauna habitat (FFH) classification scheme of the European Union’s Habitat Directive are broadly used. By date, FFH classifications are mostly expert-based. Within this...
Article
Full-text available
The success achieved by deep learning techniques in image labelling has triggered a growing interest in applying deep learning for 3D point cloud classification. To provide better insights into different deep learning architectures and their applications to ALS point cloud classification, this paper presents a comprehensive comparison among three s...
Article
Full-text available
Modern data acquisition with active or passive photogrammetric imaging techniques generally results in 3D point clouds. Depending on the acquisition or processing method, the spacing of the individual points is either uniform or irregular. In the latter case, the neighbourhood definition like for digital images (4- or 8-neighbourhood, etc.) cannot...
Preprint
Full-text available
Abstract. Permafrost is being degraded worldwide due to the change in external forcing caused by climate change. This has also been shown to affect the morphodynamics of active rock glaciers. We studied these changes, depending on the analysis, on nine or eight active rock glaciers with different characteristics in multiple epochs between 1953 and...
Article
Full-text available
Despite the important role of fungi for ecosystems, relatively little is known about the factors underlying the dynamics of their diversity. Moreover, studies do not typically consider their dark diversity: the species absent from an otherwise suitable site. Here,we examined potential drivers of local fungal dark diversity in temperate woodland and...
Article
Full-text available
With the increasing occurrence of forest fires in the mid-latitudes and the alpine region, fire risk assessments become important in these regions. Fuel assessments involve the collection of information on forest structure as, e.g., the stand height or the stand density. The potential of airborne laser scanning (ALS) to provide accurate forest stru...
Article
Full-text available
Mobile mapping is in the process of becoming a routinely applied standard tool to support administration of cities. For ensuring the usability of the mobile mapping data it is necessary to have a practical method to evaluate the quality of different systems, which reaches beyond 3D accuracy of individual points. Such a method must be objective, eas...
Preprint
Full-text available
Despite the important role of fungi for ecosystems, relatively little is known about the factors underlying the dynamics of their diversity. Moreover, studies do not typically consider their dark diversity: the species absent from an otherwise suitable site. Here, we examined potential drivers of local fungal dark diversity in temperate woodland an...
Article
Full-text available
The interdisciplinary project "Between Land and Sea" combines geological, geomorphological and paleo-environmental approaches to identify archaeological remains of the Chekka region (Lebanon). In order to record the topography of this area, the first ever scientific airborne LiDAR data acquisition in Lebanon was conducted in autumn 2018. This work...
Article
Full-text available
Accurate topographic mapping is a critical task for various environmental applications because elevation affects hydrodynamics and vegetation distributions. UAV photogrammetry is popular in terrain modelling because of its lower cost compared to laser scanning. However, this method is restricted in vegetation area with a complex terrain, due to red...
Article
Full-text available
We present an approach for automatically detecting the positions of tree trunks, for determining their corresponding diameter at breast height (DBH), and for assessing the shape of tree trunks from 3D point clouds derived from unmanned aerial vehicle borne laser scanning (ULS). The experiments are carried out with point clouds from both a RIEGL min...
Article
Full-text available
Nowadays, point clouds are the standard product when capturing reality independent of scale and measurement technique. Especially, Dense Image Matching (DIM) and Laser Scanning (LS) are state of the art capturing methods for a great variety of applications producing detailed point clouds up to billions of points. In-depth analysis of such huge poin...
Article
Full-text available
The alpine snow cover exhibits a high spatial variability in the horizontal and vertical directions even on a very small scale, mainly caused by the high variability of alpine terrain. To quantify the annual and inter-annual snow dynamics continuously reliable measurements of the temporal and spatial variability are required. While remote sensing f...
Article
Full-text available
Image matching of aerial or satellite images and Airborne Laser Scanning (ALS) are the two main techniques for the acquisition of geospatial information (3D point clouds), used for mapping and 3D modelling of large surface areas. While ALS point cloud classification is a widely investigated topic, there are fewer studies related to the image-derive...
Article
Full-text available
In this paper, we present a Remote Sens. approach to localize parking cars in a city in order to enable the development of parking space availability models. We propose to use high-resolution stereo satellite images for this problem, as they provide enough details to make individual cars recognizable and the time interval between the stereo shots a...
Article
In contrast to topographic laser scanning, laser hydrography must take into account the presence of two media. A pulsed laser beam, which enters the water from the air at an oblique angle, is refracted at the air-water boundary in the direction of the plumb line. This change in the direction described by Snellius' law is caused by a slower speed of...
Article
Full-text available
High-resolution stereo and multi-view imagery are used for digital surface model (DSM) derivation over large areas for numerous applications in topography, cartography, geomorphology, and 3D surface modelling. Dense image matching is a key component in 3D reconstruction and mapping, although the 3D reconstruction process encounters difficulties for...
Presentation
Full-text available
Alpine rivers have experienced considerable changes in channel morphology over the last century. Human disturbance and natural factors are the main drivers of changes in channel morphology that modify natural sediment and flow regimes at local, catchment and regional scale. River sediment loads are likely to increase due to increasing snow and glac...
Article
Full-text available
We studied the applicability of point clouds derived from tri-stereo satellite imagery for semantic segmentation for generalized sparse convolutional neural networks by the example of an Austrian study area. We examined, in particular, if the distorted geometric information, in addition to color, influences the performance of segmenting clutter, ro...
Article
Full-text available
Currently, products that are obtained by Unmanned Aerial Systems (UAS) image processing based on structure-from-motion photogrammetry (SfM) are being investigated for use in high precision projects. Independent of the georeferencing process being done directly or indirectly, Ground Control Points (GCPs) are needed to increase the accuracy of the ob...
Article
The surface roughness of agricultural soils is mainly related to the type of tillage performed, typically consisting of oriented and random components. Traditionally, soil surface roughness (SSR) characterization has been difficult due to its high spatial variability and the sensitivity of roughness parameters to the characteristics of the instrume...
Article
Deep learning, referring to artificial neural networks with multiple layers, is widely used for classification tasks in many disciplines including computer vision. The most popular type is the Convolutional Neural Network (CNN), commonly applied to 2D image data. However, CNNs are difficult to adapt to irregular data like point clouds. PointNet, on...
Article
Full-text available
Training dataset generation is a difficult and expensive task for LiDAR point classification, especially in the case of large area classification. We present a method to automatically extent a small set of training data by label propagation processing. The class labels could be correctly extended to their optimal neighbourhood, and the most informa...
Article
Full-text available
Point clouds derived from airborne laser scanning (ALS) and from LiDAR sensors mounted on unmanned aerial vehicles (ULS) reveal differences caused by the different sensor systems and acquisition geometries. These differences in the system characteristics are reflected in forest structure metrics that are derived from the respective point clouds. In...
Article
Full-text available
Airborne LiDAR (Light Detection And Ranging) and airborne photogrammetry are both proven and widely used techniques for the 3D topographic mapping of extended areas. Although both techniques are based on different reconstruction principles (polar measurement vs. ray triangulation), they ultimately serve the same purpose, the 3D reconstruction of th...
Article
Full-text available
Single photon sensitive LiDAR sensors are currently competing with conventional multi-photon laser scanning systems. The advantage of the prior is the potentially higher area coverage performance, which comes at the price of an increased outlier rate and a lower ranging accuracy. In this contribution, the principles of both technologies are reviewe...
Article
The landscape-human relationships on the Alps, the more populated mountain region globally, depend on tree species diversity, their canopy height and canopy gaps (soil cover). The monitoring of such forest information plays an important role in forest management planning and therefore in the definition of present and future mountain forest services...
Article
Full-text available
Structural measures for retaining and distributing water—i.e.; reservoirs, flood retentionand power plants—play a key role to protect and feed a growing world population in a rapidlychanging climate. In this work, we introduce an automated method to detect potential reservoir orretention area locations in digital terrain models. In this context, a...
Article
Full-text available
The measurements of tree attributes required for forest monitoring and management planning, e.g., National Forest Inventories, are derived by rather time-consuming field measurements on sample plots, using calipers and measurement tapes. Therefore, forest managers and researchers are looking for alternative methods. Currently, terrestrial laser sca...
Article
Full-text available
Airborne laser scanning (ALS) data can provide more than just a topographic data set for archaeological research. During data collection, laser scanning systems also record radiometric information containing object properties, and thus information about archaeological features. Being aware of the physical model of ALS scanning, the radiometric info...
Article
Full-text available
Terrestrial Laser Scanning (TLS) can be used to monitor plant dynamics with a frequency of several times per hour and with sub-centimeter accuracy, regardless of external lighting conditions. TLS point cloud time series measured at short intervals produce large quantities of data requiring fast processing techniques. These must be robust to the noi...
Data
Measurement stability results and cluster displacement analysis of the reference target, the lamppost.
Data
A time-lapse video of measurements, 20:10–07:00 h. The time lapse was recorded next to the FARO Focus 3D 120 S1 (marked with blue in Figure 1).
Data
Cluster movement tables for all presented objects in ASCII format, zip compressed (.txt). Scan times.txt contains scan DAIs in format “DD-MMM(txt)-YYYY hh:mm:ss”, with one DAI in each line. Ref_sphere_ii_center.txt files contain the center point locations fitted to the reference sphere point clouds. Each sphere has its own file, labeled “ii” in the...
Poster
In recent years, a multitude of scientific studies has succeeded in verifying the existence of significant climatechanges, in particular since the end of the Little Ice Age (c. 1850) and during the last fifty years. Mountain regions are disproportionately affected by global warming and changing precipitation conditions; temperatures in the Alps, fo...
Article
Airborne Laser Bathymetry (ALB) is an attractive technology for the measurement of shallow water bodies because of the high acquisition rate and high point densities that can be achieved. Of special interest is the application of ALB in non-navigable areas where the only alternatives are conventional terrestrial surveying by wading with a pole, mul...
Conference Paper
Full-text available
Wir stellen ein flexibles Rahmenwerk vor, mit dem sich homogene Wald-flächen in ALS-Punktwolken abgrenzen lassen. Für die Segmentierung werden vorab Wald-strukturmetriken aus der Punktwolke berechnet. Kernstück der Segmentierung ist ein iterati-ver k-means Clustering-Schritt im Merkmalsraum. Beginnend mit der gesamten Punktwolke als initiales Clust...
Conference Paper
Das Primärprodukt von Airborne Laser Scanning (ALS), eingesetzt für die Erfassung der Topographie, ist eine dichte, unklassifizierte 3D Punktwolke. Für die Ableitung nutzbarer Produkte ist daher eine Einteilung der Punkte in Klassen, Gruppen oder Segmente erforder-lich. Für eine semantische Klassifizierung muss die Information, die inhärent in der...
Article
Full-text available
We propose a flexible framework for automated forest patch delineations that exploits a set of canopy structure features computed from airborne laser scanning (ALS) point clouds. The approach is based on an iterative subdivision of the point cloud using k-means clustering followed by an iterative merging step to tackle oversegmentation. The framewo...
Chapter
This chapter presents the sediment budget of the Upper Kaunertal (Kauner valley, Ötztal Alps, Austria) for the years 2012–2014 as obtained in the framework of the PROSA (high-resolution measurements of morphodynamics in rapidly changing PROglacial Systems of the Alps) research project. An important methodological basis of this high-mountain sedimen...
Article
Full-text available
Due to the large number of technological developments in recent years, UAS systems are now used for monitoring purposes and in projects with high precision demand, such as 3D model-based creation of dams, reservoirs, historical monuments etc. These unmanned systems are usually equipped with an automatic pilot device and a digital camera (photo/vide...
Article
Full-text available
This work focuses on the accuracy estimation of canopy height models (CHMs) derived from image matching of Pléiades stereo imagery over forested mountain areas. To determine the height above ground and hence canopy height in forest areas, we use normalised digital surface models (nDSMs), computed as the differences between external high-resolution...