[postgis-devel] ST_Buffer in 3D supporting Z

[Sam Hariton]

Is anyone looking at adding the ability for st_buffer to keep Z coordinates
as well for 3-dimensional spaces?  If so, I'd like to help.

The Postgis 2.0 docs state:  This function ignores the third dimension (z)
and will always give a 2-d buffer even when presented with a 3d-geometry.

Right now

select st_astext(st_buffer(geomfromEWKT('POINT(0 0 0)'),1));
>

Generates a flat Polygon/Circle of radius 1 (completely dropping the z
dimension):

 POLYGON((1 0,0.980785280403231 -0.195090322016128,0.923879532511287
-0.382683432365089,0.831469612302546 -0.555570233019602,0.707106781186548
-0.707106781186547,0.555570233019603 -0.831469612302545,0.382683432365091
-0.923879532511286,0.19509032201613 -0.98078528040323,1.61554255216634e-15
-1,-0.195090322016126 -0.980785280403231,-0.382683432365088
-0.923879532511288,-0.555570233019601 -0.831469612302546,-0.707106781186546
-0.707106781186549,-0.831469612302544 -0.555570233019604,-0.923879532511286
-0.382683432365092,-0.98078528040323 -0.195090322016131,-1
-3.23108510433268e-15,-0.980785280403231
0.195090322016125,-0.923879532511288
 0.382683432365086,-0.831469612302547 0.555570233019599,-0.70710678118655
0.707106781186545,-0.555570233019606 0.831469612302543,-0.382683432365094
0.923879532511285,-0.195090322016132 0.98078528040323,-3.73640463187386e-15
1,0.195090322016125 0.980785280403231,0.382683432365087
0.923879532511288,0.5555702330196 0.831469612302547,0.707106781186545
0.70710678118655,0.831469612302544 0.555570233019604,0.923879532511286
0.382683432365092,0.98078528040323 0.19509032201613,1 0))

Whereas, if it had z support it should actually generate a Polyhedral
Surface/Sphere of radius 1 centered on (0 0 0)

 - Sam
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