Spatial subset
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= Interactive box selection = | = Interactive box selection = | ||
| − | # Click the {{button|text=Add raster layer}} [[Image:QGIS_2.0_addrast.png|20px]] and select the file '' | + | # Click the {{button|text=Add raster layer}} [[Image:QGIS_2.0_addrast.png|20px]] and select the file ''/geodata/raster/s2/Subset_S2A_MSIL2A_20170619T_MUL.tif''. |
# After clicking {{button|text=Open}}, the raster layer appears on the QGIS canvas. | # After clicking {{button|text=Open}}, the raster layer appears on the QGIS canvas. | ||
# {{mitem|text=Raster --> Extraction ---> Clipper...}} | # {{mitem|text=Raster --> Extraction ---> Clipper...}} | ||
| − | # Input file (raster): Choose a loaded file name fron the drop down list or click {{button|text=Select}} to browse | + | # Input file (raster): Choose a loaded file name fron the drop down list or click {{button|text=Select}} to browse 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 clipping mode '''extent''' is now active. Hold a left click on the map canvas dragging a box of your region of interest. | # The clipping mode '''extent''' is now active. Hold a left click on the map canvas dragging a box of your region of interest. | ||
Revision as of 20:51, 21 October 2018
Interactive box selection
- Click the Add raster layer
and select the file /geodata/raster/s2/Subset_S2A_MSIL2A_20170619T_MUL.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 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 masking
- 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 from Extent to Mask. 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 and specify the value 0.
- Click OK.
