Changes between Version 13 and Version 14 of PetascopeSubsets

Timestamp:

Mar 22, 2014, 12:34:46 AM (10 years ago)

Author:

Piero Campalani

Comment:

—

PetascopeSubsets

@@ -35 +35 @@
 
 Coming back to the origin question on where to put the origin of our grid coverages, we have to make it coincide to what the starting value represents in `rasdaman`, the marray origin. 
-As often done in GIS applications, the origin of an image is set to be its upper-left corner: this finally means that the origin of our rectified and referenceable grid coverages shall be there too in order to provide a coherent GML/GMLCOV coverage, where the domain is really mapped to the range of the coverage with the default coverage function. Note that placing the origin in the upper-left corner of an image means that the offset vector along the northing axis will point South, hence will have negative norm (in case the direction of the CRS axis points North!).
+As often done in GIS applications, the origin of an image is set to be its upper-left corner: this finally means that the origin of our rectified and referenceable grid coverages shall be there too in order to provide a coherent GML/GMLCOV coverage. Note that placing the origin in the upper-left corner of an image means that the offset vector along the northing axis will point South, hence will have negative norm (in case the direction of the CRS axis points North!).
 
 When it comes to further dimensions (a third elevation axis, time, etc.), the position of the origin depends on the way data has been ingested. Taking the example of a time series, if the marray origin (which we can denote as `[0:0:__:0]`, though it is more precisely described as `[dom.lo[0]:dom.lo[1]:__:dom.lo[n]`) is the earliest moment in time, then the grid origin will be the earliest moment in the series too, and the offset vector in time will point to the future (positive norm); in the other case, the origin will be the latest time in the series, and its vector will point to the past (negative norm).