[postgis-users] Raster Processing and ST_Transform

[Pierre Racine]

> Well, I cleverly unioned each tile with its neighbors before sloping, then clipped
> them back using the original extent, at least that's the theory, but the process
> never finished, which seemed unacceptable given the data size. Still learning!

Most of ST_Clip and ST_Union is now based on a very basic pixel by pixel ST_MapAlgebra. It is in our plans to get an optimized version of ST_MapAlgebra blindly copying chunk of data when possible (mostly when unioning mutually exclusive extents)  or to write c version of specific functions like ST_Clip and/or ST_Merge.

Right now those process takes time... What is the size of your coverage?

Pierre