Spatial subset
From AWF-Wiki
(Difference between revisions)
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# Click {{button|text=OK}}. | # Click {{button|text=OK}}. | ||
| − | == Vector | + | == 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. | # 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 Panel{{mitem|text=Properties --> General}}. Change the '''Data source encoding''' from {{button|text=System}} to {{button|text=UTF-8}}. Click {{button|text=UTF-8}}. | # Right click on Layer name in the Layers Panel{{mitem|text=Properties --> General}}. Change the '''Data source encoding''' from {{button|text=System}} to {{button|text=UTF-8}}. Click {{button|text=UTF-8}}. | ||
Revision as of 16:25, 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 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.
