[postgis-users] measurements of multi-features?

[pcreso at pcreso.com]

Hi all,

I have a script which is combining all geometries with a common key into a multipolygon.

My question relates to how the PostGIS measurement functions will work with such features.

In this case, many of the constituent polygons will overlap with each other.

Will st_area provide the sum of all the areas bounded by each constituent polygon, irrespective of any overlaps, or the actual area covered by the multipolygon?

Similarly for multilines where some parts of some lines are contiguous, what is the returned length of such multilines?

Are there any known gotchas when working with multi geometries comprising overlapping members?


Thanks,

  Brent