Changes between Version 8 and Version 9 of PetascopeSubsets

Timestamp:

Feb 28, 2014, 5:50:35 PM (11 years ago)

Author:

Piero Campalani

Comment:

add note on index CRSs

PetascopeSubsets

@@ -37 +37 @@
    * ''regular axis'': when a grid axis has equal spacing between each of its points, then it is assumed that the sample space of the points is equal to this spacing (resolution) and that the grid points are in the middle of this interval;
    * ''irregular axis'': when a grid axis has an uneven spacing between its points, then there is no (currently implemented) way to either express or deduce its sample space, hence 0D points are assumed here (no footprint).
+
+It is important to note that sample spaces are meaningful when areas are legal in the Coordinate Reference System (CRS): this is not the case for Index CRSs, where the allowed values are integrals only. Even on regular axes, points in an Index CRSs can only be points, and hence will have 0D footprint. Refer to [IndexCrss this] page for more details.
 
 Such policy is translated in practice to a ''point-is-pixel-center'' interpretation of regular rectified images. The following art explains it visually:
@@ -202 +204 @@
 === Irregular axis: point is point
 
+It is reminded that "point is point" is also applied to regular axes on [IndexCrss index coordinate reference systems].
 
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