Spatial subset

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(→‎Masking by vector polygon)
(→‎Masking by vector polygon)
 
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# Click the {{button|text=Open Data Source Manager}} [[Image:QGIS_3.0_datasource.png|30px]] and {{button|text=Add raster layer}} [[Image:QGIS_2.0_addrast.png|20px]] and select a multiband raster file.
 
# Click the {{button|text=Open Data Source Manager}} [[Image:QGIS_3.0_datasource.png|30px]] and {{button|text=Add raster layer}} [[Image:QGIS_2.0_addrast.png|20px]] and select a multiband raster file.
 
# {{mitem|text=Raster --> Extraction ---> Clip Raster by Extent}}
 
# {{mitem|text=Raster --> Extraction ---> Clip Raster by Extent}}
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# Input file (raster): Choose a loaded file from the drop down list or click {{button|text=Select}} to browse for a file.
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# Input layer: Choose a loaded raster file from the drop down list or click [[File:QGIS_file_select.png]] to browse for a file.
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# Output file:  click {{button|text=Select}} to choose a new file name for the subset image.
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# Define the clipping extent by clicking [[File:QGIS_file_select.png]] and select '''Draw on canvas'''. The clipping mode is now active. Hold a left click on the map canvas dragging a box of your region of interest.
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# Define the clipping extent by clicking{{button|text=...}} and '''Select extent from canvas''' The clipping mode is now active. Hold a left click on the map canvas dragging a box of your region of interest.
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# Clipped (extent): click [[File:QGIS_file_select.png]] to choose a new file name for the subset image.
 
# Adjust the extent coordinates in the text file rounding the coordinates (upper left and lower right).
 
# Adjust the extent coordinates in the text file rounding the coordinates (upper left and lower right).
 
[[File:Qgis_raster_clipper.png|700px]]
 
[[File:Qgis_raster_clipper.png|700px]]
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# Click {{button|text=OK}}.
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* Click {{button|text=Run}}.
  
 
== Masking by vector polygon ==
 
== Masking by vector polygon ==
 
* Load the vector file (e.g. administrative boundary).
 
* Load the vector file (e.g. administrative boundary).
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* Select a community of your choice: right click {{mitem|text=Open Attribute Table}}    
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* Select a community of your choice: right click {{mitem|text=Open Attribute Table}}
  
 
* {{mitem|text=Raster --> Extraction ---> Clip Raster by Mask Layer...}}
 
* {{mitem|text=Raster --> Extraction ---> Clip Raster by Mask Layer...}}
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# Input file (raster): Choose a loaded file name from the drop down list or click {{button|text=Select}} to browse to a file. * Make sure that the CRS is the same like the image file (here WGS84/UTM Zone 32, EPSG:32632) that you wish to be clipped!
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# Input layer: Choose a loaded raster file from the drop down list or click [[File:QGIS_file_select.png]] to browse to a file.
 
# Mask layer: Select the vector file (s. above).
 
# Mask layer: Select the vector file (s. above).
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# Switch checkbox on: '''Selected features only'''.
 
 
# Assign a specofied nodata value: {{button|text=65535}}
 
# Assign a specofied nodata value: {{button|text=65535}}
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# Clipped (mask)):  click {{button|text=Select}} to choose a new file name for the subset image.
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# Switch the checkbox on: '''Match the extent of the clipped raster to the extent of the mask layer'''. All image data outside the polygon will be masked.
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# Switch the checkbox on: '''Crop the extent of the target dataset to the extent of the cutline'''. All image data outside the polygon will be masked.
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# Clipped (extent)):  click {{button|text=Select}} to choose a new file name for the subset image.
 
# Click {{button|text=Run}}.
 
# Click {{button|text=Run}}.
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[[File:Qgis_raster_mask.png|700px]]
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[[File:Qgis_raster_mask.png|400px]]
 
[[Category: Working with Raster Data]]
 
[[Category: Working with Raster Data]]

Latest revision as of 10:57, 31 May 2021

[edit] Interactive box selection

  1. Click the Open Data Source Manager QGIS 3.0 datasource.png and Add raster layer QGIS 2.0 addrast.png and select a multiband raster file.
  2. Raster --> Extraction ---> Clip Raster by Extent
  3. Input layer: Choose a loaded raster file from the drop down list or click QGIS file select.png to browse for a file.
  4. Define the clipping extent by clicking QGIS file select.png and select Draw on canvas. The clipping mode is now active. Hold a left click on the map canvas dragging a box of your region of interest.
  5. Clipped (extent): click QGIS file select.png to choose a new file name for the subset image.
  6. Adjust the extent coordinates in the text file rounding the coordinates (upper left and lower right).

Qgis raster clipper.png

  • Click Run.

[edit] Masking by vector polygon

  • Load the vector file (e.g. administrative boundary).
  • Select a community of your choice: right click Open Attribute Table
  • Raster --> Extraction ---> Clip Raster by Mask Layer...
  1. Input layer: Choose a loaded raster file from the drop down list or click QGIS file select.png to browse to a file.
  2. Mask layer: Select the vector file (s. above).
  3. Assign a specofied nodata value: 65535
  4. Switch the checkbox on: Match the extent of the clipped raster to the extent of the mask layer. All image data outside the polygon will be masked.
  5. Clipped (extent)): click Select to choose a new file name for the subset image.
  6. Click Run.

Qgis raster mask.png

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