The Resample operation resamples a
raster map from the map's current
georeference to another target georeference. The coordinate of each output pixel is used to calculate a new value from close-by pixel values in the input map. Three resampling methods are available: nearest neighbour, bilinear interpolation, and bicubic interpolation.
In raster operations (e.g. MapCalc, Cross), all input raster maps must have the same georeference. Thus, prior to such operations, use Resample:
- to combine raster maps from various sources, when maps use different coordinate systems (projections) or different georeferences (pixel size): resample the maps to one common georeference;
- to combine satellite imagery of different dates or resolutions: create a georef tiepoints for each set of images, then resample the images preferably to a georef corners;
- to combine satellite images with rasterized vector maps: rasterize the vector data on the georef tiepoints of the satellite images, or, in case you prefer North-oriented raster maps, rasterize the vector maps with a georef corners, and resample the images with the georef tiepoints to this georef corners;
- to combine scanned photographs with rasterized vector data, or to rectify scanned aerial photographs: create a georef tiepoints, a georef direct linear or a georef orthophoto for the photo, then resample the photo to a georef corners.