I'm trying to perform some spatial relationship analysis using Postgis functions like
st_dfullywithin. I searched and found that for any SRID, using the
geography type gives the results in metres which works well for
st_dwithin. However, the
st_dfullywithin the arguments need to be of type
geometry so this approach does not work.
My base SRID is 4283 and I've tried transforming the SRID of the geometry objects to SRID 3577 which still does not work.
As a test, I tried to measure the distance between two points using different SRID and the geometry and geography types. I believe the units of 3577 is in metres, but when I run the test to get the distance between two points using SRID 3577 it returns the results in degrees, but changing the type to geography returns metres.
I thought changing the SRID to one with metres should return metres? If not, how can you work in metres?
EDIT: The query to get the distance which gives the result in degrees is,
select st_distance(st_geomfromtext('POINT(150.9319747 -33.8482439)', 3557), st_geomfromtext('POINT(151.9319747 -34.8482439)', 3557))
If I use the same SRID, I have to use the following query to get the result in metres
select st_distance(st_geomfromtext('POINT(150.9319747 -33.8482439)', 3557)::geography, st_geomfromtext('POINT(151.9319747 -34.8482439)', 3557)::geography)
My ultimate aim is to fine
geoms that are within a given radius of a point,
select * from table_1 a where ST_DWithin(st_transform(a.geom, 3557), st_transform(st_geomfromtext('POINT(150.9319747 -33.8482439)', 4283),3557), 50000);
Inspite of using the different SRIDs, the relationship still considers degrees and not meters.