M. Hollaus

Flood hazard mapping is currently in a transitional phase involving the use of data and methods that were traditionally in the domain of local studies in a regional or nationwide context. Challenges include the representation of local information such as hydrological particularities and small hydraulic structures, as well as computational and labou...

Purpose of the Review Many LiDAR remote sensing studies over the past decade promised data fusion as a potential avenue to increase accuracy, spatial-temporal resolution, and information extraction in the final data products. Here, we performed a structured literature review to analyze relevant studies on these topics published in the last decade a...

Terrestrial LiDAR scanning (TLS) has the potential to revolutionize forestry by enabling the precise estimation of aboveground biomass, vital for forest carbon management. This study addresses the lack of comprehensive benchmarking for leaf-filtering algorithms used in TLS data processing and evaluates four widely recognized geometry-based leaf-fil...

Low-cost lidar sensors mounted on unmanned aircraft systems (UAS) can be applied for the acquisition of small-scale forestry applications providing many advantages over airborne laser scanning (ALS), such as flexibility, low flight altitude and small laser footprint. Compared to 3D data generated from dense image matching using photogrammetry, lida...

The utilization of terrestrial laser scanning (TLS) and airborne laser scanning (ALS) point cloud data in forest inventory studies has significantly increased. Fusing of TLS and ALS point cloud data has been recognized as an effective approach in forest studies. In this regard, co-registration of point clouds is considered one of the crucial steps...

Flood hazard mapping is currently in a transitional phase involving the use of data and methods that were traditionally the domain of local studies in a regional or nation-wide context. Challenges include the representation of local information such as hydrological particularities and small hydraulic structures, and computational and labour costs....

The FOR-instance dataset (available at https://doi.org/10.5281/zenodo.8287792) addresses the challenge of accurate individual tree segmentation from laser scanning data, crucial for understanding forest ecosystems and sustainable management. Despite the growing need for detailed tree data, automating segmentation and tracking scientific progress re...

Mapping and monitoring of habitats are requirements for protecting biodiversity. In this study, we investigated the benefit of combining airborne (laser scanning, image-based point clouds) and satellite-based (Sentinel 1 and 2) data for habitat classification. We used a two level random forest 10-fold leave-location-out cross-validation workflow to...

Abstract 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 dar...

Remote sensing-based forest investigation and monitoring have become more affordable and applicable in the past few decades. The current bottleneck limiting practical use of the vast volume of remote sensing data lies in the lack of affordable, reliable, and detailed field references, which are required for necessary calibrations of satellite and a...

Microwave and optical imaging methods react differently to different land surface parameters and, thus, provide highly complementary information. However, the contribution of individual features from these two domains of the electromagnetic spectrum for tree species classification is still unclear. For large-scale forest assessments, it is moreover...

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...

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...

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...

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...

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...

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...

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...

In airborne photogrammetry it is common sense to collect many images with high overlap both in along and in across track direction when a highly accurate digital surface model should be generated. Such highly redundant data aids the processing chain as inaccuracies or gross outliers resulting from one stereo pair can be minimized or even corrected...

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...

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...

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...

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...

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...

The aim of this study was to investigate the capabilities of two date satellite-derived image-based point clouds (IPCs) to estimate forest aboveground biomass (AGB). The data sets used include panchromatic WorldView-2 stereo-imagery with 0.46 m spatial resolution representing 2014 and 2016 and a detailed digital elevation model derived from airborn...

The Sentinel-1 satellites provide the formerly unprecedented combination of high spatial and temporal resolution of dual polarization synthetic aperture radar data. The availability of dense time series enables the derivation and analysis of temporally filtered annual backscatter signals. The study concentrates on the use of Sentinel-1 seasonal bac...

Many biophysical forest properties such as wood volume and leaf area index (LAI) require prior knowledge on either photosynthetic or non-photosynthetic components. Laser scanning appears to be a helpful technique in nondestructively quantifying forest structures, as it can acquire an accurate three-dimensional point cloud of objects. In this study,...

Radar sensors have the potential to retrieve vertical forest structure measurements thanks to their capability to penetrate into the foliage. However, studies are needed in order to understand better the interaction of radar beams with the canopy. The most commonly used radar technique for estimating forest parameters operates from spacecraft at di...

Diameter at breast height (DBH) is one of the most important parameter in forestry. With increasing use of terrestrial and airborne laser scanning in forestry, new exceeding possibilities to directly derive DBH emerge. In particular, high resolution point clouds from laser scanners on board unmanned aerial systems (UAS) are becoming available over...

Proper knowledge about resources in forest management is fundamental. One of the most important parameters of forests is their size or spatial extension. By determining the area of treefall gaps inside the compartments, a more accurate yield can be calculated and the scheduling of forestry operations could be planned better. Several field- and remo...

Space-borne LiDAR systems can potentially assist large-area assessments of forest resources, in particular when a subset of the acquired LiDAR footprints is combined with field surveys of forest stand characteristics at footprint location. When combined, space-borne LiDAR geolocation error and the footprint size may however have considerable effect...

Classification of wood and leaf components of trees is an essential prerequisite for deriving vital tree attributes, such as wood mass, leaf area index (LAI) and woody-to-total area. Laser scanning emerges to be a promising solution for such a request. Intensity based approaches are widely proposed, as different components of a tree can feature dis...

Strong wind disturbances can affect large forested areas and often occur irregularly within a forest. Due to this, identifying damaged sites and estimating the extent of these losses are crucial for the harvesting management of salvage logging. Furthermore, the location should be surveyed as soon as possible after the disturbance to prevent the deg...

This contribution explores the potential of ULS data in forest inventories.

Multi-temporal airborne laserscanning data for forestry applications During the last decade airborne laserscanning (ALS) data has been established as a suitable data source for three-dimensional description of forests and for deriving forest parameters. For the study area Vorarlberg, Austria, the potential of multi-temporal ALS data (data from 2004...

Terrestrial laser scanning (TLS) is an effective tool for retrieving forest attributes. For example, stem diameters can be estimated from the TLS point cloud by applying automatic algorithms, which often approximate the stem cross section by using a circle or a cylinder. However, the cross section of a tree stem is never exactly a circle. Moreover,...

Terrestrial laser scanning (TLS) is a promising technique for plot-wise acquisition of geometric attributes of forests. However, there still exists a need for TLS applications in mountain forests where tree stems' growing directions are not vertical. This paper presents a novel method to model tree stems precisely in an alpine landslide-affected fo...

The 3rd EARSeL SIG Forestry Workshop, Krakow, Poland

The availability of Sentinel-1 sensor provided the former unprecedented availability of high resolution dual-polarization Synthetic Aperture Radar (SAR) data over European continent. Dense time-series enables the study of the seasonal variability of C-Band SAR backscatter over forested areas. In this study, the Sentinel-1 backscatter and its annual...

During the last ten years, mobile laser scanning (MLS) systems have become a very popular and efficient technology for capturing reality in 3D. A 3D laser scanner mounted on the top of a moving vehicle (e.g. car) allows the high precision capturing of the environment in a fast way. Mostly this technology is used in cities for capturing roads and bu...

Terrestrial Laser Scanning (TLS) is an effective tool in forest research and management. However, accurate estimation of tree parameters still remains challenging in complex forests. In this paper, we present a novel algorithm for stem modeling in complex environments. This method does not require accurate delineation of stem points from the origin...

Terrestrial Laser Scanning (TLS) is an effective tool in forest research and management. However, accurate estimation of tree parameters still remains challenging in complex forests. In this paper, we present a novel algorithm for stem modeling in complex environments. This method does not require accurate delineation of stem points from the origin...

During the last ten years, mobile laser scanning (MLS) systems have become a very popular and efficient technology for capturing reality in 3D. A 3D laser scanner mounted on the top of a moving vehicle (e.g. car) allows the high precision capturing of the environment in a fast way. Mostly this technology is used in cities for capturing roads and bu...

The recently launched Sentinel-1A provides the high resolution Synthetic Aperture Radar (SAR) data with very high temporal coverage over large parts of European continent. Short revisit time and dual polarization availability supports its usability for forestry applications. The following study presents an analysis of the potential of the multi-tem...

The recently launched Sentinel-1A provides the high resolution Synthetic Aperture Radar (SAR) data with very high temporal coverage over large parts of European continent. Short revisit time and dual polarization availability supports its usability for forestry applications. The following study presents an analysis of the potential of the multi-tem...

The causes of landslides are manifold and highly influenced by multiple interacting natural and anthropogenic factors. In particular human induced land cover changes, such as deforestation and afforestation are known to strongly influence slope stability. Thus, we investigate the understanding of differences between forested and non-forested condit...

This study analyses the underestimation of tree and shrub heights for different airborne laser scanner systems and point cloud distribution within the vegetation column. Reference data was produced by a novel UAV-borne laser scanning (ULS) with a high point density in the complete vegetation column. With its physical parameters (e.g. footprint) and...

This study analyses the underestimation of tree and shrub heights for different airborne laser scanner systems and point cloud distribution within the vegetation column. Reference data was produced by a novel UAV-borne laser scanning (ULS) with a high point density in the complete vegetation column. With its physical parameters (e.g. footprint) and...

Landslides or other forms of mass movement influence slope stability, and are known to have significant effects on vegetation patterns. Observation of such surface patterns may result in valuable information for understanding the kinematics of the landslide. In forested regions, tree growth anomaly is often served as an indicator of shallow landsli...

Landslides play a key role in landscape evolution in the Eastern Alps. These geomorphic phenomena are influenced by multiple interdependent and interacting natural and anthropogenic factors. An in-depth evaluation of the spatial distribution of existing landslides enables to gain first insights into potentially hazardous areas. Morphometric analysi...

Highlights: Very high point density UAS-based laser scanner point clouds of an alluvial forest acquired with the RIEGL VUX-SYS were analyzed w.r.t. forestry applications. With point densities >1500 points/m² and accuracies <2 cm the study shows that individual stems and branches, understory, lying deadwood, and the terrain are clearly represented i...

Highlights: This study presents a new open-access dataset of 18 plots from alpine forests of the Alpine Space. Eight detection algorithms were tested and evaluated against forest inventory data using a novel, automated matching procedure. Forest structure remains a key issue limiting tree detection, and algorithms would probably benefit from an ada...

Highlights: The operationalization of five different applications in forestry within the scientific software package OPALS is presented. The OPALS forestry package enables handling and processing of large point cloud data in a research as well as in a production environment.

Highlights: Based on multi-temporal ALS data the site index of forest stands was assessed for a mountainous study area in Austria. The applied approach is based on derived tree top heights. The promising results show good agreements with forest inventory data and provide new insights in forest productivity analyses.

Flood mapping from Synthetic Aperture Radar (SAR) data has attracted considerable attention in recent years. Most available algorithms typically focus on single-image techniques which do not take into account the backscatter signature of a land surface under non-flooded conditions. In this study, harmonic analysis of a multi-temporal time series of...

In this study, eight airborne laser scanning (ALS)-based single tree detection methods are benchmarked and investigated. The methods were applied to a unique dataset originating from different regions of the Alpine Space covering different study areas, forest types, and structures. This is the first benchmark ever performed for different forests wi...

Airborne Laser Scanning (ALS) data hold a great deal of promise in monitoring the reduction of single trees and forests with high accuracy. In the literature, the canopy height model (CHM) is the main input used frequently for forest change detection. ALS also has the key capability of delivering 3D point clouds, not only from the top canopy surfac...

Large area tasks as for example obtaining information about forested areas are already operational in forest management as the use of remote sensing data and related methods has become a standard. In contrast, terrestrial forest inventories are still obligatory and will probably never be fully replaceable by automatically methods. Data fusion of in...

Die Nützlichkeit von 3D Information für die Forstwirtschaft wurde im letzten Jahrzehnt im Rahmen von wissenschaftlichen Studien und Anwendungsbeispielen eindeutig dargestellt und belegt. Die aus der Differenz von Oberflächenmodellen und Geländemodellen berechnete normalisierte Kronenhöhe spielt dabei eine zentrale Rolle, da sich daraus direkt Baum-...

Landslides of the slide-type movement represent potentially damaging phenomena for residents, their properties and infrastructure all over the world. The causes of these geomorphic processes are manifold as multiple interacting natural and anthropogenic factors influence their occurrence. Numerous studies reveal that human induced land cover change...

Mountainous forests comprise some of Europe’s most stunning, yet inaccessible landscape. Although forests represent a key resource of mountain environments, their valorisation is hampered by accessibility constraints. A comprehensive understanding of such remote terrain via an efficient mapping, management, harvesting and transport of wood products...

Kurzfassung In dieser Arbeit wird ein hochauflösendes Satellitenbild (IKONOS 2) gemeinsam mit La-ser-Scanning-Daten objekt-orientiert analysiert und klassifiziert. Aus dem manuell nachbe-arbeiteten Ergebnis werden die Gebäude herausgefiltert und mittels eines neu entwickelten Algorithmus halb-automatisch generalisiert. Die resultierenden Objekte di...

Individual tree crowns can be delineated from dense airborne laser scanning (ALS) data and their species can be classified from the spatial distribution and other variables derived from the ALS data within each tree crown. This study reports a new clustering approach to delineate tree crowns in three dimensions (3-D) based on ellipsoidal tree crown...

Full-waveform (FWF) airborne laser scanning (ALS) systems became available for operational data acquisition around the year 2004. These systems typically digitize the analogue backscattered echo of the emitted laser pulse with a high frequency. FWF digitization has the advantage of not limiting the number of echoes that are recorded for each indivi...

Extracting 3D tree models based on terrestrial laser scanning (TLS) point clouds is a challenging task as trees are complex objects. Current TLS devices acquire high-density data that allow a detailed reconstruction of the tree topology. However, in dense forests a fully automatic reconstruction of trees is often limited by occlusion, wind influenc...

The amount of dead wood is a significant parameter for the description and assessment of forest habitat quality under the terms of the Habitats directive and Natura 2000 guidelines. EU member states are obliged by the Natura 2000 regulations to report on habitat quality in a regular interval of six years. To fulfil this task, the areas should be su...

Dead wood is an important habitat characteristic in forests. However, dead wood lying on the ground below a canopy is difficult to detect from remotely sensed data. Data from airborne laser scanning include measurement of surfaces below the canopy, thus offering the potential to model objects on the ground. This paper describes a new line template...

The usage of forest parameters deduced from airborne laser scanning (ALS) has become a standard for many forestry applications. The 3D-information of forested areas provides a good input for estimating forest parameters. A fundamental application is delineating forests according to a forest definition, which commonly includes height, crown cover, w...

The structure of forests influences the global biochemical cycles and can serve as an indicator to estimate the conservation potential for biodiversity and to determine forest stand resistance to disturbances. Airborne laser scanning (ALS) systems have been proven as suitable tools to provide horizontal as well as explicit vertical information due...

Poster– Earth & Space Science Informatics Section: 3D Spatial Data, Analysis, Visualization and Infrastructures in Geosciences - From 3D Point Clouds to Information The knowledge about the position of forest roads is important for the management and protection of forests. Most often this information is not available on a digital form so that it ca...

Roughness is a physical parameter of surfaces which should include the surface complexity in geophysical models. In hydrodynamic modeling, e.g., roughness should estimate the resistance caused by the surface on the flow, or in remote sensing, how the signal is scattered. Roughness needs to be estimated as a parameter of the model. This has been ide...

Deadwood was identified as an important indicator for habitat condition and biodiversity in forests. The assessment of downed trees is therefore part of sustainable forest management and ecological monitoring. However, manual quantification of deadwood in forests is challenging, time consuming, and considered cost-inefficient. Fullwaveform airborne...

The monitoring of flood events with synthetic aperture radar (SAR) sensors has attracted a considerable amount of attention during the last decade, owing to the growing interest in using spaceborne data in near-real time flood management. Most existing methods for classifying flood extent from SAR data rely on pure image processing techniques. In t...

This paper presents a methodology for the derivation of structural parameters and stem volume in forests based on Airborne Laser Scanning (ALS) data. We describe three different measures of horizontal and vertical canopy structure: (1) tree crown segmentation, (2) compactness of vegetation patches, and (3) vertical layering of vegetation patches an...

Wälder bedecken nahezu ein Drittel der globalen Landoberfläche und haben neben dem signifikanten Einfluss auf die globalen biogeochemischen Stoffkreisläufe und den Erhalt der Biodiversität auch eine bedeutende Rolle im Rahmen der Diskussionen um erneuerbare Energien. Fernerkundungsdaten und -methoden bieten hierbei die Möglichkeit für eine flächend...

Extracting 3D tree models based on high-density terrestrial laser scanning (TLS) point clouds with automatic, semi-automatic or manual methods is a challenging task as trees are complex, individual objects. Various publications in this research field show the demand for tree reconstruction methods based on TLS data. Data sets acquired with current...

Vegetation structure was identified to have significant influence on the course of environmental processes. For complex applications in environmental context, such as radiative transfer modelling in forests, highly detailed and accurate geometric depiction of the vegetation is among the basic requirements to ensure as realistic conditions as possib...

Forests play a significant role in the global biogeochemical and -physical cycles and particularly the complex three-dimensional forest canopy structure influences the fluxes of energy and matter between the atmosphere and forests. Assessing this structure quantitatively using conventional fieldwork or traditional remote sensing methods is difficul...

Full-waveform LiDAR is an active remote sensing technique that provides the scattering properties of the targets i.e. amplitude and echo width (EW) in addition to 3D point clouds. The amplitude provides information on the target's reflectance and the EW is a measure for the range variation of scatterers within the laser footprint contributing to a...