Digital Elevation Model (DEM) Processing

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(Loading, merging and reprojection of DEM data)
(Loading, merging and reprojection of DEM data)
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# [[Exercise 01: First steps in QGIS|Add]] the raster layers ''N51E009.hgt'' and ''N51E010.hgt'' to a new [[QGIS]] project (from ''geodata\raster\DEM'', see [[Course data]]). Arrange the first above the latter layer.  
 
# [[Exercise 01: First steps in QGIS|Add]] the raster layers ''N51E009.hgt'' and ''N51E010.hgt'' to a new [[QGIS]] project (from ''geodata\raster\DEM'', see [[Course data]]). Arrange the first above the latter layer.  
 
# Merging layers
 
# Merging layers
#* Select {{mitem|text=Raster --> Miscellaneous --> Merge}}. In the appearing menu, click the {{button|text=Select}} in beside the {{button|text=Input files}} field. Browse for the maps ''N51E009.hgt'' and ''N51E010.hgt'' and select both (by clicking with pressed {{button|text=Ctrl}} key).  
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#* Select {{mitem|text=Raster --> Miscellaneous --> Merge}}. In the appearing menu, click the {{button|text=Select}} beside the {{button|text=Input files}} field. Browse for the maps ''N51E009.hgt'' and ''N51E010.hgt'' and select both (by clicking with pressed {{button|text=Ctrl}} key) (figure '''A''').  
 
#* Select an output directory and file name (e.g. ''N510_merged'') under {{button|text=Output file}}. Confirm with {{mitem|text=OK}}.
 
#* Select an output directory and file name (e.g. ''N510_merged'') under {{button|text=Output file}}. Confirm with {{mitem|text=OK}}.
 
# Reprojecting layers (warp)
 
# Reprojecting layers (warp)
 
#* Select {{mitem|text=Raster --> Projections --> Warp (reprojects)}}.
 
#* Select {{mitem|text=Raster --> Projections --> Warp (reprojects)}}.
 
#* As {{button|text=Input file}} choose the merged layer from the preceding step. Select an according path and file name for {{button|text=Output file}}.
 
#* As {{button|text=Input file}} choose the merged layer from the preceding step. Select an according path and file name for {{button|text=Output file}}.
#* Determine the correct source and target coordinate system ({{button|text=Source SRS}} and {{button|text=Target SRS}} -- The coordinate system of the source layer is WGS84 (EPSG:4326). Use UTM32 (EPSG:32632) as target.
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#* Determine the correct source and target coordinate system ({{button|text=Source SRS}} and {{button|text=Target SRS}}) -- The coordinate system of the source layer is WGS84 (EPSG:4326). Use UTM32 (EPSG:32632) as target.
#* Confirm with {{button|text=OK}}.  
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#* Confirm with {{button|text=OK}}.
 +
 
 +
[[file:RemSens_Exercise05_01.png|thumb|left|450px|'''Figure A:''' Merge dialogue and file browser in [[QGIS]] 2.0]]
  
 
==Clipping and Resampling of DEM data==
 
==Clipping and Resampling of DEM data==

Revision as of 10:35, 21 January 2014

Construction.png sorry: 

This section is still under construction! This article was last modified on 01/21/2014. If you have comments please use the Discussion page or contribute to the article!

This article is part of the QGIS tutorial 2013/14.
In this article you will learn how to pre-process and enhance digital elevation model (DEM) data, as well as how to create a 3D-Model

Loading, merging and reprojection of DEM data

  1. Add the raster layers N51E009.hgt and N51E010.hgt to a new QGIS project (from geodata\raster\DEM, see Course data). Arrange the first above the latter layer.
  2. Merging layers
    • Select Raster --> Miscellaneous --> Merge. In the appearing menu, click the Select beside the Input files field. Browse for the maps N51E009.hgt and N51E010.hgt and select both (by clicking with pressed Ctrl key) (figure A).
    • Select an output directory and file name (e.g. N510_merged) under Output file. Confirm with OK.
  3. Reprojecting layers (warp)
    • Select Raster --> Projections --> Warp (reprojects).
    • As Input file choose the merged layer from the preceding step. Select an according path and file name for Output file.
    • Determine the correct source and target coordinate system (Source SRS and Target SRS) -- The coordinate system of the source layer is WGS84 (EPSG:4326). Use UTM32 (EPSG:32632) as target.
    • Confirm with OK.
Figure A: Merge dialogue and file browser in QGIS 2.0

Clipping and Resampling of DEM data

  1. Create a boundary polygon
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