Estimation of Vegetation-Induced Flow Resistance for Hydraulic Computations Using Airborne Laser Scanning Data

The effect of vegetation in hydraulic computations can be significant. This effect is important for flood computations. Today, the necessary terrain information for flood computations is obtained by airborne laser scanning techniques. The quality and density of the airborne laser scanning information allows for more extensive use of these data in flow computations. In this paper, known methods are improved and combined into a new simple and objective procedure to estimate the hydraulic resistance of vegetation on the flow in the field. State-of-the-art airborne laser scanner information is explored to estimate the vegetation density. The laser scanning information provides the base for the calculation of the vegetation density parameter ωp using the Beer–Lambert law. In a second step, the vegetation density is employed in a flow model to appropriately account for vegetation resistance. The use of this vegetation parameter is superior to the common method of accounting for the vegetation resistance in the bed resistance parameter for bed roughness. The proposed procedure utilizes newly available information and is demonstrated in an example. The obtained values fit very well with the values obtained in the literature. Moreover, the obtained information is very detailed. In the results, the effect of vegetation is estimated objectively without the assignment of typical values. Moreover, a more structured flow field is computed with the flood around denser vegetation, such as groups of bushes. A further thorough study based on observed flow resistance is needed.

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TOWARDS AUTOMATIC SINGLE-SENSOR MAPPING BY MULTISPECTRAL AIRBORNE LASER SCANNING

ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences ◽

10.5194/isprsarchives-xli-b3-155-2016 ◽

2016 ◽

Vol XLI-B3 ◽

pp. 155-162 ◽

Cited By ~ 8

Author(s):

E. Ahokas ◽

J. Hyyppä ◽

X. Yu ◽

X. Liang ◽

L. Matikainen ◽

...

Keyword(s):

Land Cover ◽

Tree Species ◽

Forest Inventory ◽

Laser Scanning ◽

Laser Scanner ◽

Ground Surface ◽

Airborne Laser Scanning ◽

Forest Mapping ◽

Airborne Laser Scanner ◽

Airborne Laser

This paper describes the possibilities of the Optech Titan multispectral airborne laser scanner in the fields of mapping and forestry. Investigation was targeted to six land cover classes. Multispectral laser scanner data can be used to distinguish land cover classes of the ground surface, including the roads and separate road surface classes. For forest inventory using point cloud metrics and intensity features combined, total accuracy of 93.5% was achieved for classification of three main boreal tree species (pine, spruce and birch).When using intensity features – without point height metrics - a classification accuracy of 91% was achieved for these three tree species. It was also shown that deciduous trees can be further classified into more species. We propose that intensity-related features and waveform-type features are combined with point height metrics for forest attribute derivation in area-based prediction, which is an operatively applied forest inventory process in Scandinavia. It is expected that multispectral airborne laser scanning can provide highly valuable data for city and forest mapping and is a highly relevant data asset for national and local mapping agencies in the near future.

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TOWARDS AUTOMATIC SINGLE-SENSOR MAPPING BY MULTISPECTRAL AIRBORNE LASER SCANNING

ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences ◽

10.5194/isprs-archives-xli-b3-155-2016 ◽

2016 ◽

Vol XLI-B3 ◽

pp. 155-162 ◽

Cited By ~ 1

Author(s):

E. Ahokas ◽

J. Hyyppä ◽

X. Yu ◽

X. Liang ◽

L. Matikainen ◽

...

Keyword(s):

Land Cover ◽

Tree Species ◽

Forest Inventory ◽

Laser Scanning ◽

Laser Scanner ◽

Ground Surface ◽

Airborne Laser Scanning ◽

Forest Mapping ◽

Airborne Laser Scanner ◽

Airborne Laser

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Nonparametric estimation of stem volume using airborne laser scanning, aerial photography, and stand-register data

Canadian Journal of Forest Research ◽

10.1139/x05-246 ◽

2006 ◽

Vol 36 (2) ◽

pp. 426-436 ◽

Cited By ~ 93

Author(s):

M Maltamo ◽

J Malinen ◽

P Packalén ◽

A Suvanto ◽

J Kangas

Keyword(s):

Laser Scanning ◽

Laser Scanner ◽

Airborne Laser Scanning ◽

Data Sources ◽

Aerial Images ◽

Stem Volume ◽

Scanner Data ◽

Airborne Laser Scanner ◽

Airborne Laser ◽

Other Information

In forest management planning and forestry decision-making there is a continuous need for higher quality information on forest resources. The aim of this study was to improve the quality of forest resource information acquired by airborne laser scanning by combining it with aerial images and current stand-register data. A k-MSN (most similar neighbor) application was constructed for the prediction of the plot and stand volumes of standing trees. The application constructed used various data sources, including laser scanner data, aerial digital photographs, class variables describing a stand, and updated old stand volumes. The ability of these data sources to predict stem volume was tested together and separately. In the airborne laser scanner data based k-MSN application, characteristics of canopy quantiles were used as independent variables. The results show that with respect to individual plot and stand volume estimation approaches, the laser-based technique is a superior one. The results were improved further when other information sources were used together with the laser scanner data. Using a combination of laser scanner data, aerial images, and class variables (on the grounds of the current forest database) improved the root mean square error (RMSE) of the estimated plot volume by 15% (from 16% to 13%) as compared to using laser scanner data on their own. When the results were averaged at the stand level, the accuracy improved considerably, but the use of other information sources together with airborne laser scanner data did not further improve the results as it did at the plot level. The RMSE of stand volume was about 6% in all data combinations where airborne laser scanning information was used. One conclusion is that making use of additional available data sources together with laser material improves the reliability of plot volume estimates. As these additional data typically mean no extra material costs (since they are available in any case), making combined use of these data and laser scanner data improves the cost efficiency of a forest inventory.

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Processing and analysis of airborne full-waveform laser scanning data for the characterization of forest structure and fuel properties

Revista de Teledetección ◽

10.4995/raet.2020.14551 ◽

2020 ◽

pp. 95

Author(s):

P. Crespo-Peremarch ◽

L. A. Ruiz

Keyword(s):

Forest Structure ◽

Laser Scanning ◽

Software Tool ◽

Understory Vegetation ◽

Airborne Laser Scanning ◽

Vegetation Density ◽

Regression Methods ◽

Full Waveform ◽

Airborne Laser ◽

Pulse Density

This PhD thesis addresses the development of full-waveform airborne laser scanning (ALSFW) processing and analysis methods to characterize the vertical forest structure, in particular the understory vegetation. In this sense, the influence of several factors such as pulse density, voxel parameters (voxel size and assignation value), scan angle at acquisition, radiometric correction and regression methods is analyzed on the extraction of ALSFW metric values and on the estimate of forest attributes. Additionally, a new software tool to process ALSFW data is presented, which includes new metrics related to understory vegetation. On the other hand, occlusion caused by vegetation in the ALSFW, discrete airborne laser scanning (ALSD) and terrestrial laser scanning (TLS) signal is characterized along the vertical structure. Finally, understory vegetation density is detected and determined by ALSFW data, as well as characterized by using the new proposed metrics.

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Investigations on intra-annual elevation changes using multi-temporal airborne laser scanning data: case study Engabreen, Norway

Annals of Glaciology ◽

10.3189/172756405781812592 ◽

2005 ◽

Vol 42 ◽

pp. 195-201 ◽

Cited By ~ 34

Author(s):

Thomas Geist ◽

Hallgeir Elvehøy ◽

Miriam Jackson ◽

Johann Stötter

Keyword(s):

Mass Balance ◽

Laser Scanning ◽

Laser Scanner ◽

Remote Sensing Data ◽

Control Area ◽

Airborne Laser Scanning ◽

Time Interval ◽

Scanner Data ◽

Glacier Surface ◽

Airborne Laser

AbstractKey issues of glacier monitoring are changes in glacier geometry and glacier mass. As accurate direct measurements are costly and time-consuming, the use of various remote-sensing data for glacier monitoring is explored. One technology used and described here is airborne laser scanning. The method enables the derivation of high-quality digital elevation models (DEMs) with a vertical and horizontal accuracy in the sub-metre range. Between September 2001 and August 2002, three laser scanner data acquisition flights were carried out, covering the whole area of Engabreen, Norway, and corresponding well to the measurement dates for the mass-balance year 2001/02. The data quality of the DEMs is assessed (e.g. by comparing the values with a control area which has been surveyed independently or GPS ground profiles measured during the flights). For the whole glacier, surface elevation change and consequently volume change is calculated, quantified and compared with traditional mass-balance data for the same time interval. For the winter term, emergence/submergence velocity is determined from laser scanner data and snow-depth data and is compared with velocity measurements at stakes. The investigations reveal the high potential of airborne laser scanning for measuring the extent and the topography of glaciers as well as changes in geometry (Δarea, Δvolume).

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EVALUATING THE POSSIBILITY OF TREE SPECIES CLASSIFICATION WITH DUAL-WAVELENGTH ALS DATA

ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences ◽

10.5194/isprs-archives-xlii-2-w13-1097-2019 ◽

2019 ◽

Vol XLII-2/W13 ◽

pp. 1097-1103

Author(s):

M. Pilarska ◽

W. Ostrowski

Keyword(s):

Spatial Data ◽

Tree Species ◽

Laser Scanning ◽

Laser Scanner ◽

Point Clouds ◽

Airborne Laser Scanning ◽

Tree Canopy ◽

Species Classification ◽

Airborne Laser ◽

Simultaneous Acquisition

Abstract. Airborne laser scanning (ALS) plays an important role in spatial data acquisition. One of the advantages of this technique is laser beam penetration through vegetation, which makes it possible to not only obtain data on the tree canopy but also within and under the canopy. In recent years, multi-wavelength airborne laser scanning has been developed. This technique consists of simultaneous acquisition of point clouds in more than one band. The aim of this experiment was to examine and assess the possibilities of tree segmentation and species classification in an urban area. In this experiment, point clouds registered in two wavelengths (532 and 1064&thinsp;nm) were used for tree segmentation and species classification. The data were acquired with a Riegl VQ-1560i-DW laser scanner over Elblag, Poland, during August 2018. Tree species collected by a botanist team within terrain measurements were used as a reference in the classification process. Within the experiment segmentation and classification process were performed. Regarding the segmentation, TerraScan software and Li et al.’s algorithm, implemented in LidR package were used. Results from both methods are clearly over-segmented in comparison to the manual segments. In Terrasolid segmentation, single reference segments are over-segmented in 28% of cases, whereas, for LidR, over-segmentation occurred in 73% of the segments. According the classification results, Thuja, Salix and Betula were the species, for which the highest classification accuracy was achieved.

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Global Airborne Laser Scanning Data Providers Database (GlobALS)—A New Tool for Monitoring Ecosystems and Biodiversity

Remote Sensing ◽

10.3390/rs12111877 ◽

2020 ◽

Vol 12 (11) ◽

pp. 1877 ◽

Cited By ~ 1

Author(s):

Krzysztof Stereńczak ◽

Gaia Vaglio Laurin ◽

Gherardo Chirici ◽

David A. Coomes ◽

Michele Dalponte ◽

...

Keyword(s):

Laser Scanning ◽

Structural Changes ◽

Multiple Scales ◽

Laser Scanner ◽

Airborne Laser Scanning ◽

Data Availability ◽

Global Network ◽

Airborne Laser ◽

High Resolution Imagery ◽

Worldwide Network

Protection and recovery of natural resource and biodiversity requires accurate monitoring at multiple scales. Airborne Laser Scanning (ALS) provides high-resolution imagery that is valuable for monitoring structural changes to vegetation, providing a reliable reference for ecological analyses and comparison purposes, especially if used in conjunction with other remote-sensing and field products. However, the potential of ALS data has not been fully exploited, due to limits in data availability and validation. To bridge this gap, the global network for airborne laser scanner data (GlobALS) has been established as a worldwide network of ALS data providers that aims at linking those interested in research and applications related to natural resources and biodiversity monitoring. The network does not collect data itself but collects metadata and facilitates networking and collaborative research amongst the end-users and data providers. This letter describes this facility, with the aim of broadening participation in GlobALS.

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ASSESSMENT OF LANDSLIDE-INDUCED DISPLACEMENT AND DEFORMATION OF ABOVE-GROUND OBJECTS USING UAV-BORNE AND AIRBORNE LASER SCANNING DATA

ISPRS Annals of Photogrammetry Remote Sensing and Spatial Information Sciences ◽

10.5194/isprs-annals-iv-2-w5-461-2019 ◽

2019 ◽

Vol IV-2/W5 ◽

pp. 461-467 ◽

Cited By ~ 3

Author(s):

T. Zieher ◽

M. Bremer ◽

M. Rutzinger ◽

J. Pfeiffer ◽

P. Fritzmann ◽

...

Keyword(s):

Laser Scanning ◽

Laser Scanner ◽

Point Clouds ◽

Airborne Laser Scanning ◽

Additional Information ◽

3D Point Clouds ◽

Airborne Laser ◽

Displacement Vectors ◽

Multi Temporal ◽

Aerial Vehicle

Abstract. Multi-temporal 3D point clouds acquired with a laser scanner can be efficiently used for an area-wide assessment of landslide-induced surface changes. In the present study, displacements of the Vögelsberg landslide (Tyrol, Austria) are assessed based on available data acquired with airborne laser scanning (ALS) in 2013 and data acquired with an unmanned aerial vehicle (UAV) equipped with a laser scanner (ULS) in 2018. Following the data pre-processing steps including registration and ground filtering, buildings are segmented and extracted from the datasets. The roofs, represented as multi-temporal 3D point clouds are then used to derive displacement vectors with a novel matching tool based on the iterative closest point (ICP) algorithm. The resulting mean annual displacements are compared to the results of a geodetic monitoring based on an automatic tracking total station (ATTS) measuring 53 retroreflective prisms across the study area every hour since May 2016. In general, the results are in agreement concerning the mean annual magnitude (ATTS: 6.4&thinsp;cm within 2.2 years, 2.9&thinsp;cm a&minus;1; laser scanning data: 13.2&thinsp;cm within 5.4 years, 2.4&thinsp;cm a&minus;1) and direction of the derived displacements. The analysis of the laser scanning data proved suitable for deriving long-term landslide displacements and can provide additional information about the deformation of single roofs.

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Airborne laser scanning and usefulness for hydrological models

Advances in Geosciences ◽

10.5194/adgeo-5-57-2005 ◽

2005 ◽

Vol 5 ◽

pp. 57-63 ◽

Cited By ~ 33

Author(s):

M. Hollaus ◽

W. Wagner ◽

K. Kraus

Keyword(s):

Laser Scanning ◽

Laser Scanner ◽

Airborne Laser Scanning ◽

Scanner Data ◽

Digital Terrain Models ◽

Mountainous Regions ◽

Digital Terrain ◽

Terrain Models ◽

Airborne Laser ◽

Land Cover Maps

Abstract. Digital terrain models form the basis for distributed hydrologic models as well as for two-dimensional hydraulic river flood models. The technique used for generating high accuracy digital terrain models has shifted from stereoscopic aerial-photography to airborne laser scanning during the last years. Since the disastrous floods 2002 in Austria, large airborne laser-scanning flight campaigns have been carried out for several river basins. Additionally to the topographic information, laser scanner data offer also the possibility to estimate object heights (vegetation, buildings). Detailed land cover maps can be derived in conjunction with the complementary information provided by high-resolution colour-infrared orthophotos. As already shown in several studies, the potential of airborne laser scanning to provide data for hydrologic/hydraulic applications is high. These studies were mostly constraint to small test sites. To overcome this spatial limitation, the current paper summarises the experiences to process airborne laser scanner data for large mountainous regions, thereby demonstrating the applicability of this technique in real-world hydrological applications.

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ULS LiDAR SUPPORTED ANALYSES OF LASER BEAM PENETRATION FROM DIFFERENT ALS SYSTEMS INTO VEGETATION

ISPRS Annals of Photogrammetry Remote Sensing and Spatial Information Sciences ◽

10.5194/isprsannals-iii-3-233-2016 ◽

2016 ◽

Vol III-3 ◽

pp. 233-239 ◽

Cited By ~ 3

Author(s):

M. Wieser ◽

M. Hollaus ◽

G. Mandlburger ◽

P. Glira ◽

N. Pfeifer

Keyword(s):

Laser Scanning ◽

Reference Data ◽

Structural Characteristics ◽

Laser System ◽

Laser Scanner ◽

Physical Parameters ◽

Deciduous Trees ◽

Airborne Laser Scanner ◽

Vegetation Height ◽

Airborne Laser

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 its relative accuracy within the block as stated in Section 2.2 the reference data is supposed to be highly suitable to detect the highest point of the vegetation. An airborne topographic (ALS) and topo-bathymetric (ALB) system were investigated. All data was collected in a period of one month in leaf-off condition, while the dominant tree species in the study area are deciduous trees. By robustly estimating the highest 3d vegetation point of each laser system the underestimation of the vegetation height was examined in respect to the ULS reference data. This resulted in a higher under-estimation of the airborne topographic system with 0.60 m (trees) and 0.55 m (shrubs) than for the topo-bathymetric system 0.30 m (trees) and 0.40 m (shrubs). The degree of the underestimation depends on structural characteristics of the vegetation itself and physical specification of the laser system.

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