For basic boolean logic, I would highly suggest just using Reclass, as it’s much faster
https://postgis.net/docs/RT_ST_Reclass.html Generally speaking I think any algebraic operations and I recall even CASE statements allowed in SQL are allowed though I haven’t fully tested that. If you are doing more complex things than that, you probably should just create a mapalgebra callback function to use. There are some already part of PostGIS proper that are mostly written in plpgsql so you can peak and see how they work https://postgis.net/docs/RT_reference.html#Raster_Processing_MapAlgebra_Callbacks and then stuff into - https://postgis.net/docs/RT_ST_MapAlgebra.html From: Robert Burgholzer <rburg...@vt.edu> Sent: Tuesday, July 30, 2024 2:09 PM To: PostGIS Users Discussion <postgis-users@lists.osgeo.org> Subject: Detailed st_mapalgebra reference? We are doing a ton of precip raster analysis and rectification, and we are struggling to find details on the algebraic expressions that we can use, ie, "[rast1] + [rast2]" is great if we are adding, but we are also interested in boolean calculations etc. The basic postgis reference page is great for understanding syntax but I am looking for recipes or a large raster calculator reference. Thanks on advance, Robert -- Robert W. Burgholzer 'Making the simple complicated is commonplace; making the complicated simple, awesomely simple, that's creativity.' - Charles Mingus
