2.6 More about georeferences
A georeference is a service object, which stores the relation between the rows and
columns in raster map(s) and the ground-coordinates (X, Y). A georeference is
needed for raster maps and uses a coordinate system. If you work with several raster
maps of the same area, and you want to overlay them (e.g. with the Cross operation),
it is important that all maps have the same number of rows and columns, and the
same pixel size. The pixels in both maps thus refer to the same position on the
ground. Therefore all raster maps of the same area should have the same
georeference. Let us look at a georeference.