The GeoTIFF specification includes a data item, GTRasterTypeGeoKey (#1025), which may be set to either RasterPixelIsArea (maybe the default, but not clear in 7.2.1), or RasterPixelIsPoint.
The GTRasterTypeGeoKey value SHALL be:
* 0 to indicate that the Raster type is undefined or unknown; or
* 1 to indicate that the Raster type is PixelIsArea; or
* 2 to indicate that the Raster type is PixelIsPoint; or
* 32767 to indicate that the Raster type is user-defined.
Recommendation: the use of 0 (undefined) or 32767 (user-defined) is not recommended
RasterPixelIsArea defines that a pixel represents an area in the real world,
while RasterPixelIsPoint defines a pixel to represent a point in the real world.
Often this is useful to distinguish the behavior of optical sensors that average
light values over an area vs. raster data which is point oriented like an
elevation sample at a point.
This is a real world issue with Key Global Regional DEMs. For these, some follow the
In "Arc-speak" these are
View of the grid for a 1" geographic grid in Alaska, where the spacing is about
15 m x 30 m. The black star represents the geographic position of a pixel.
A number of programs (e.g. GDAL, GRASS) turn all DEMs into Pixel-Is-Area, transforming all coordinates by a half pixel.
References:
Much older references
Last revision 5/29/2022