Spatial subset
From AWF-Wiki
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(→Interactive box selection) |
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# Input file (raster): Choose a loaded file name fron the drop down list or click {{button|text=Select}} to browse to a file. | # Input file (raster): Choose a loaded file name fron the drop down list or click {{button|text=Select}} to browse to a file. | ||
# Output file: click {{button|text=Select}} to choose a new file name for the subset image. | # Output file: click {{button|text=Select}} to choose a new file name for the subset image. | ||
| − | # The ''' | + | # The clipping mode '''extent''' is now active. Hold a left click on the map canvas dragging a box of your region of interest. |
# Adjust the extent coordinates in the text file rounding the coordinates of 1 (upper left corner) x, y and 2 (lower right corner) x, y. | # Adjust the extent coordinates in the text file rounding the coordinates of 1 (upper left corner) x, y and 2 (lower right corner) x, y. | ||
[[File:Qgis_raster_clipper.png|600px]] | [[File:Qgis_raster_clipper.png|600px]] | ||
Revision as of 16:19, 25 October 2017
Interactive box selection
- Click the Add raster layer
and select the file C:/OSGeo4W64/geodata/raster/s2/Subset_S2A_MSIL2A_20170619T.tif.
- After clicking Open, the raster layer appears on the QGIS canvas.
- Raster --> Extraction ---> Clipper...
- Input file (raster): Choose a loaded file name fron the drop down list or click Select to browse to a file.
- Output file: click Select to choose a new file name for the subset image.
- The clipping mode extent is now active. Hold a left click on the map canvas dragging a box of your region of interest.
- Adjust the extent coordinates in the text file rounding the coordinates of 1 (upper left corner) x, y and 2 (lower right corner) x, y.
- Click OK.
Vector Polygon
- Load the vector file C:\OSGeo4W64\var\geodata\vector\Landkreis_Goe_neu_utm32.shp. This is the actual boundary of the county Göttingen. We create a new vecto file with the boundary of the municipality Göttingen.
- Right click on Layer name in the Layers PanelProperties --> General. Change the Data source encoding from System to UTF-8. Click UTF-8.
- Right click on Layer name in the Layers Panel and open the Attribute table.
- Click
and select by the expression: "NAME_4" ='Göttingen'. Select.
- Right click on Layer name in the Layers Panel Save as.... Fill the form as shown below.
Make sure that the CRS is the same like the image file.
- Click Run.
- Raster --> Extraction ---> Clipper...
- Input file (raster): Choose a loaded file name fron the drop down list or click Select to browse to a file (see above).
- Output file: click Select to choose a new file name for the subset image.
- Change the clipping mode Extent to Mask. Hold a left click on the map canvas dragging a box of your region of interest.
- Choose the newly created polygon of the municipality as Mask Layer.
- 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.
- Switch the 'No data value checkbox on.
- Click OK.
