On Jan 28, 2008, at 4:56 AM, Olivier Tournaire wrote:
1. As far as I know, PostGIS is ale to store 3D data. Am I right ?
It can store z-variants of point, line, polygon, multipoint, multiline, multipolygon.
2. If I create a spatial index on a table which contains 3D geometries, is it a real 3D index, or the objects are projected onto the ground and the the index is built with this projection ?
Indexes are 2-d.
3. Last, but not least, is it possible to have operations on geometries in a 3D framework. For example, it I test if the point (0,0,50) is within the polygon ( (-10,-10,0) (-10,10,0) (10,10,0) (10,-10,0) ), what is the answer ? In other words, is the result obtained with taking into account the Z coordinate or not ?
Z-values are ignored in tests, and occasionally used in building resultants for things like intersections.
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