I'm working in the SRID 4326 system and need to compute the area of rectilinear polygons. Our geometry (geom) column is in WKB format
When I execute the ST_Area function it appears my results are returned in squared degrees when I execute a call as follows:
public.ST_Area(geom)/1000000 from production.schemaA where item = '123456'
Then if I cast the geom column to geography the result returned was 33.97 km2
This is still quite a bit off from what I get checking the area of the SAME polygon in Arc Map and QGIS Desktop (Field calculator method) about 43.37 km2
I have investigated using the ST_Transform function to transform out of 4326 but this doesn't work as you have to know which UTM/WGS SRID to use in advance based on the (UTM/ZONE) zone you are working in. We'll be hitting our global database of polygons all over the world had identifying the specific zone is cumbersome.
Example: public.ST_Area(geom::geography)/1000000 from production.schemaA where item = '123456'
There are threads that are close to this issue but not exactly the same issue of have no solution.