scholarly journals Integration von hochauflösenden Fernerkundungs- und Geländemodelldaten für die Landschaftsvisualisierung

1997 ◽  
Vol 52 (1) ◽  
pp. 21-26
Author(s):  
P. Pirchl ◽  
P. Hirtz ◽  
M. Suter ◽  
D. Nüesch
Keyword(s):  
Land Cover ◽  
Aerial Photographs ◽  
Surface Model ◽  
Northern Switzerland ◽  
Transition Zones ◽  
Gis Tools ◽  
Digital Elevation ◽  
Elevation Data ◽  
Digital Elevation Data ◽  
Elevation Model

Abstract. This paper presents experiments for realistic landscape visualization using high resolution digital aerial photographs and elevation modeis. The natural environment of a river in northern Switzerland is visualized. Photogrammetrically measured digital elevation data and ortho-rectified remote sensing imagery (Landsat Thematic Mapper/TM and aerial photographs) are combined to compute realistic 3D views of the landscape. To renderthe landscape more realistically, the digital elevation model (DEM) is transformed to a digital surface model (DSM), representing the surface and including objects like forests or bushes. For this transformation land cover information and GIS tools were used. Unnaturally looking vertical borders between different land cover classes were suppressed by interpolating transition zones. Additionally, 3D objects (trees) are used in the foreground to increase the realism of the views.

scholarly journals Environmental classification of administrative units of the Ukrainian Carpathians

2014 ◽  
pp. 245-253
Author(s):  
Ivan Kruhlov
Keyword(s):  
Cluster Analysis ◽  
Standard Deviation ◽  
Satellite Images ◽  
Environmental Classification ◽  
Digital Elevation ◽  
Elevation Data ◽  
Digital Elevation Data ◽  
Administrative Units ◽  
Elevation Model

Boundaries of 43 administrative units (raions and oblast towns) were digitized and manually rectified using official schemes and satellite images. SRTM digital elevation data were used to calculate mean relative elevation and its standard deviation for each unit, as well as to delineate altitudinal bioclimatic belts and their portions within the units. These parameters were used to classify the units via agglomerative cluster analysis into nine environmental classes. Key words: cluster analysis, digital elevation model, geoecosystem, geo-spatial analysis.

scholarly journals Aboveground Biomass Changes in Tropical Montane Forest of Northern Borneo Estimated Using Spaceborne and Airborne Digital Elevation Data

2020 ◽  
Vol 12 (22) ◽  
pp. 3677
Author(s):  
Ho Yan Loh ◽  
Daniel James ◽  
Keiko Ioki ◽  
Wilson Vun Chiong Wong ◽  
Satoshi Tsuyuki ◽  
...  
Keyword(s):  
Aboveground Biomass ◽  
Montane Forest ◽  
Tropical Montane Forest ◽  
Surface Model ◽  
Managed Forests ◽  
Mean Values ◽  
Tropical Regions ◽  
Digital Elevation ◽  
Elevation Data ◽  
Digital Elevation Data

Monitoring anthropogenic disturbances on aboveground biomass (AGB) of tropical montane forests is crucial, but challenging, due to a lack of historical AGB information. We examined the use of spaceborne (Shuttle Radar Topographic Mission Digital Elevation Model (SRTM) digital surface model (DSM)) and airborne (Light Detection and Ranging (LiDAR)) digital elevation data to estimate tropical montane forest AGB changes in northern Borneo between 2000 and 2012. LiDAR canopy height model (CHM) mean values were used to calibrate SRTM CHM in different pixel resolutions (1, 5, 10, and 30 m). Regression analyses between field AGB of 2012 and LiDAR CHM means at different resolutions identified the LiDAR CHM mean at 1 m resolution as the best model (modeling efficiency = 0.798; relative root mean square error = 25.81%). Using the multitemporal AGB maps, the overall mean AGB decrease was estimated at 390.50 Mg/ha, but AGB removal up to 673.30 Mg/ha was estimated in the managed forests due to timber extraction. Over the 12 years, the AGB accumulated at a rate of 10.44 Mg/ha/yr, which was attributed to natural regeneration. The annual rate in the village area was 8.31 Mg/ha/yr, which was almost 20% lower than in the managed forests (10.21 Mg/ha/yr). This study identified forestry land use, especially commercial logging, as the main driver for the AGB changes in the montane forest. As SRTM DSM data are freely available, this approach can be used to estimate baseline historical AGB information for monitoring forest AGB changes in other tropical regions.

scholarly journals A Parallel Computing Approach to Spatial Neighboring Analysis of Large Amounts of Terrain Data Using Spark

Sensors ◽  
2021 ◽  
Vol 21 (2) ◽  
pp. 365
Author(s):  
Jianbo Zhang ◽  
Zhuangzhuang Ye ◽  
Kai Zheng
Keyword(s):  
Parallel Computing ◽  
Spatial Data ◽  
Parallel Performance ◽  
Digital Elevation ◽  
Hadoop Distributed File System ◽  
Elevation Data ◽  
Calculation Results ◽  
Digital Elevation Data ◽  
Elevation Model ◽  
Computing Approach

Spatial neighboring analysis is an indispensable part of geo-raster spatial analysis. In the big data era, high-resolution raster data offer us abundant and valuable information, and also bring enormous computational challenges to the existing focal statistics algorithms. Simply employing the in-memory computing framework Spark to serve such applications might incur performance issues due to its lack of native support for spatial data. In this article, we present a Spark-based parallel computing approach for the focal algorithms of neighboring analysis. This approach implements efficient manipulation of large amounts of terrain data through three steps: (1) partitioning a raster digital elevation model (DEM) file into multiple square tile files by adopting a tile-based multifile storing strategy suitable for the Hadoop Distributed File System (HDFS), (2) performing the quintessential slope algorithm on these tile files using a dynamic calculation window (DCW) computing strategy, and (3) writing back and merging the calculation results into a whole raster file. Experiments with the digital elevation data of Australia show that the proposed computing approach can effectively improve the parallel performance of focal statistics algorithms. The results also show that the approach has almost the same calculation accuracy as that of ArcGIS. The proposed approach also exhibits good scalability when the number of Spark executors in clusters is increased.

scholarly journals WORLDDEM – A NOVEL GLOBAL FOUNDATION LAYER

2015 ◽  
Vol XL-3/W2 ◽  
pp. 183-187 ◽  
Author(s):  
G. Riegler ◽  
S. D. Hennig ◽  
M. Weber
Keyword(s):  
Digital Terrain Model ◽  
Current Status ◽  
Disruptive Technology ◽  
Surface Model ◽  
Terrain Model ◽  
Digital Terrain ◽  
Digital Elevation ◽  
Elevation Data ◽  
Elevation Model ◽  
German Aerospace

Airbus Defence and Space’s WorldDEM™ provides a global Digital Elevation Model of unprecedented quality, accuracy, and coverage. The product will feature a vertical accuracy of 2m (relative) and better than 6m (absolute) in a 12m x 12m raster. The accuracy will surpass that of any global satellite-based elevation model available. WorldDEM is a game-changing disruptive technology and will define a new standard in global elevation models. <br><br> The German radar satellites TerraSAR-X and TanDEM-X form a high-precision radar interferometer in space and acquire the data basis for the WorldDEM. This mission is performed jointly with the German Aerospace Center (DLR). Airbus DS refines the Digital Surface Model (e.g. editing of acquisition, processing artefacts and water surfaces) or generates a Digital Terrain Model. Three product levels are offered: WorldDEMcore (output of the processing, no editing is applied), WorldDEM™ (guarantees a void-free terrain description and hydrological consistency) and WorldDEM DTM (represents bare Earth elevation). <br><br> Precise elevation data is the initial foundation of any accurate geospatial product, particularly when the integration of multi-source imagery and data is performed based upon it. Fused data provides for improved reliability, increased confidence and reduced ambiguity. This paper will present the current status of product development activities including methodologies and tool to generate these, like terrain and water bodies editing and DTM generation. In addition, the studies on verification & validation of the WorldDEM products will be presented.

Geomorphometry of the Glacial Cirques in Zardkuh Mountain, Iran

2016 ◽  
Vol 16 (2) ◽  
pp. 94-101
Author(s):  
Ali Ahmadabadi ◽  
Varduhi Sargsyan
Keyword(s):  
Environmental Science ◽  
Shape Features ◽  
Topographic Map ◽  
Quaternary Period ◽  
Digital Elevation ◽  
Second Derivatives ◽  
Curvature Index ◽  
Elevation Data ◽  
Digital Elevation Data ◽  
Elevation Model

AbstractCirques as one of the glacial erosional forms are suitable indicators to recognize the environmental conditions of the Quaternary period. Therefore, considering the importance of glacial cirque landforms, identifying and mapping the distribution of the circus with their shape features meets the need of environmental science, especially geomorphology. In this paper, in order to identify the quantitative features of cirques in Zardkuh region, the second derivatives, including second-degree curvature of the plan, profile and general curvature along with slope as a primarily derivative were used from geomorphometry indices. To this end, 20 meter resolution digital elevation model was generated from 1: 25,000 topographic map which was used in the geomorphometric analysis. The result shows that secondary derivatives had higher performance in identifying the feature shapes of glacial cirques. Likewise, the plan curvature Index could truly present the headwall around the circus as well as profile curvature clearly showed the avalanche path. In conclusion, it seems that the second derivative indicators, including curvature’s family, have high capability to extract and detect different natural shapes from digital elevation data.

Comparison of Late Pleistocene and Modern Glacier Extents in Central Nepal Based on Digital Elevation Data and Satellite Imagery

1998 ◽  
Vol 49 (3) ◽  
pp. 241-254 ◽  
Author(s):  
Christopher C. Duncan ◽  
Andrew J. Klein ◽  
Jeffrey G. Masek ◽  
Bryan L. Isacks
Keyword(s):  
Late Pleistocene ◽  
Equilibrium Line Altitude ◽  
Small Temperature ◽  
New Techniques ◽  
Central Nepal ◽  
Digital Elevation ◽  
Elevation Data ◽  
Digital Elevation Data ◽  
Elevation Model ◽  
Temperature Depression

Late Pleistocene and modern ice extents in central Nepal are compared to estimate equilibrium line altitude (ELA) depressions. New techniques are used for determining the former extent of glaciers based on quantitative, objective geomorphic analyses of a ∼90-m resolution digital elevation model (DEM). For every link of the drainage network, valley form is classified as glacial or fluvial based on cross-valley shape and slope statistics. Down-valley transitions from glacial to fluvial form indicate the former limits of glaciation in each valley. Landsat Multispectral Scanner imagery for the same region is used to map current glacier extents. For both full-glacial and modern cases, ELAs are computed from the glacier limits using the DEM and a toe-to-headwall altitude ratio of 0.5. Computed ELA depressions range from 100–900 m with a modal value of ∼650 m and a mean of ∼500 m, values consistent with previously published estimates for the central Himalaya but markedly smaller than estimates for many other regions. We suggest that this reflects reduced precipitation, rather than a small temperature depression, consistent with other evidence for a weaker monsoon under full-glacial conditions.

Urban Flood Mapping

2017 ◽  
Author(s):  
Indra Riyanto ◽  
Lestari Margatama
Keyword(s):  
Natural Disasters ◽  
Satisfying Condition ◽  
Three Dimensions ◽  
Urban Flood ◽  
Digital Elevation ◽  
Elevation Data ◽  
Recent Occurrence ◽  
Elevation Model ◽  
Digital Elevation Model Data ◽  
Potential Area

The recent degradation of environment quality becomes the prime cause of the recent occurrence of natural disasters. It also contributes in the increase of the area that is prone to natural disasters. Flood history data in Jakarta shows that flood occurred mainly during rainy season around January – February each year, but the flood area varies each year. This research is intended to map the flood potential area in DKI Jakarta by segmenting the Digital Elevation Model data. The data used in this research is contour data obtained from DPP–DKI with the resolution of 1 m. The data processing involved in this research is extracting the surface elevation data from the DEM, overlaying the river map of Jakarta with the elevation data. Subsequently, the data is then segmented using watershed segmentation method. The concept of watersheds is based on visualizing an image in three dimensions: two spatial coordinates versus gray levels, in which there are two specific points; that are points belonging to a regional minimum and points at which a drop of water, if placed at the location of any of those points, would fall with certainty to a single minimum. For a particular regional minimum, the set of points satisfying the latter condition is called the catchments basin or watershed of that minimum, while the points satisfying condition form more than one minima are termed divide lines or watershed lines. The objective of this segmentation is to find the watershed lines of the DEM image. The expected result of the research is the flood potential area information, especially along the Ciliwung river in DKI Jakarta.

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