Spatial subset

Revision as of 11:53, 9 November 2020

Interactive box selection

1. Click the Open Data Source Manager and Add raster layer 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 to browse for a file.
4. Define the clipping extent by clicking 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 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).

• Click Run.

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 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!
2. Mask layer: Select the vector file (s. above).
3. Switch checkbox on: Selected features only.
4. Assign a specofied nodata value: 65535
5. Clipped (mask)): click Select to choose a new file name for the subset image.
6. 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.
7. Click Run.