[postgis-devel] ST_Tesselate and TINS is it supposed to maintain solidness

[Paragon Corporation]

I tried tesselating a cube

NOTE: 

SELECT ST_Dimension(ST_GeomFromText('POLYHEDRALSURFACE Z( ((0 0 0, 0 0 1, 0
1 1, 0 1 0, 0 0 0)), 
		((0 0 0, 0 1 0, 1 1 0, 1 0 0, 0 0 0)), ((0 0 0, 1 0 0, 1 0
1, 0 0 1, 0 0 0)), 
		((1 1 0, 1 1 1, 1 0 1, 1 0 0, 1 1 0)), 
		((0 1 0, 0 1 1, 1 1 1, 1 1 0, 0 1 0)), ((0 0 1, 1 0 1, 1 1
1, 0 1 1, 0 0 1)) )'))

Comes back as a solid -- ST_Dimension = 3


But when I tesselate it, I get back a TIN with ST_Dimension 2
SELECT ST_Dimension(ST_Tesselate(ST_GeomFromText('POLYHEDRALSURFACE Z( ((0 0
0, 0 0 1, 0 1 1, 0 1 0, 0 0 0)), 
		((0 0 0, 0 1 0, 1 1 0, 1 0 0, 0 0 0)), ((0 0 0, 1 0 0, 1 0
1, 0 0 1, 0 0 0)), 
		((1 1 0, 1 1 1, 1 0 1, 1 0 0, 1 1 0)), 
		((0 1 0, 0 1 1, 1 1 1, 1 1 0, 0 1 0)), ((0 0 1, 1 0 1, 1 1
1, 0 1 1, 0 0 1)) )')))

= 2

Rendering both them look the same to me.

Why is the TIN not considered closed is a TIN never considered closed?


See attached images I color coded the triangles in resulting tin and as far
as I can tell rotating it all sides were accounted for.



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