[postgis-devel] Raster todo list

[Pierre Racine]

> I'm sorry for jumping in the discussion...I feel that the function bborie is much
> like ST_Collect, am I right?

What I understand up to now, to make a correspondance between the vector version and the raster version of ST_Accum, ST_Collect and ST_Union:

-ST_Accum() would create an array of raster (I don't see any use for that up to now).
-ST_Collect() would roughly merge rasters together (last pixel value or first only in the case of overlap so no way to blend pixel values together)
-ST_Union() would be the most sophisticated (but slower than ST_collect) way of merging rasters together. It could use a set of initial raster, state raster and final raster expressions to determine the final value of the resulting raster pixels. Predefined options could be FIRST, LAST, MAX, MIN, MEAN, SUM, RANGE, COUNT...

All of them are aggregates functions.

Pierre