The domain of a coverage is the set of valid input values. In Apache SIS, the domain of grid coverages is described by the Grid­Geometry class. This class contains the following information:

• A grid extent (a.k.a. grid envelope), often inferred from the image size in pixels.
• A grid to CRS conversion, typically as a scale followed by a translation.
• A georeferenced envelope, which can be inferred from the grid extent and the grid to CRS conversion.
• A Coordinate Reference System (CRS) which is the target of the grid to CRS conversion.
• An estimation of grid resolution along each CRS axes.
• An indication of whether conversion for some axes is linear or not.

One of the most important property listed above is the grid to CRS conversion, which defines how to map pixel coordinates to "real world" coordinates such as latitudes and longitudes. This relationship is often linear (an affine transform), but not necessarily; GridGeometry accepts non-linear conversions as well.