I have a layer containing 10 polygons all overlapping at various locations.
Each polygon has a value of '1' in a column called "value"
How do I Union the polygons (rows) together such that the values in the "value" column are added for each output polygon?
What I'm after is the ability to add the values from the columns of the input features such that a combined overlay is produced. What I mean is, where 8 polygons overlap within the feature, the output union geometry has a value of "8".
And yes, this can be done using raster, but is there a way to do this using vector and SQL Spatial?
I would like to to this using SQL Spatial, ie. using PostGIS or SQLite.
There are discussions on this site on how to Union polygons together, but how to combine values from the inputs is something I cannot find.