What is the fastest way to create a polygon of the part of PostGIS raster that is not filled with NoData values?

Question

I have a raster table in PostGIS. For each row, I want to create a polygon that represents the part of the raster that is filled with data (not NODATA). I found out that ST_Polygon(rast) does the job. However, it works very very slowly.
Is there another solution for this problem that works faster?

radouxju · Answer

you could try with ST_DumpAsPolygons (which uses gdal internally). To avoid making unnecessary polygons, make sure the you set a single value for each pixel that should end up in a polygon (e.g. with ST_Reclass).

Answered by radouxju on May 27, 2021

What is the fastest way to create a polygon of the part of PostGIS raster that is not filled with NoData values?

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