I have two 3D linestrings (geometry type
LINESTRING Z) in a PostGIS database that intersect in 2D space, but not in 3D space. Given that there is technically no 'shared portion' of geometry in 3D, how is the Z value returned by
Here is the query I am using:
SELECT feature, str1, (ST_Dump(geom)).geom.ST_Z as z_value FROM (SELECT ST_Intersection(linework.geom, align.geom) as geom, linework.feature, linework.str1 FROM align INNER JOIN linework ON ST_Intersects(align.geom, linework.geom) WHERE ST_isvalid(align.geom)='t' AND ST_isvalid(linework.geom)='t') q1;
What I would like is a query that returns the z value of the point of intersection but on one of the linestrings only.
linework contains surveyed features that are crossed by an alignment in
align - I would like to 'lift' elevations off the surveyed features at the points of intersection but I'm not sure how to go about it.