[postgis-users] make the buffer in 3d

[Obe, Regina]

Eehab,
 
If you are just dealing with point geometries and you care about just 3d
distance rather than representation, then , use ST_Length3D.  There is
no distance 3d, but there is a length 3d.
 
Although I think I answered this question before so maybe there was
something wrong with my answer.  It would be helpful to know what was
wrong with the answer. I admit I didn't really try it.
 
Also shouldn't your visual result be a sphere rather than a cylinder?
Where is your cylinder coming from?
 
Anyrate here is my answer again
 
In this case, I'm going to assume p is ST_MakePoint(1,2,3) and your 3d
limiting distance is 10
 
SELECT gid, the_geom
FROM sometable, (SELECT ST_MakePoint(1,2,3) As the_geom) As p
WHERE ST_DWithin(sometable.the_geom, p.the_geom, 10)
AND ST_Length3D(ST_MakeLine(sometable.the_geom, p.the_geom)) < 10
 
(The ST_DWithin even though its a 2d check, will be useful because it
will use indexes and any 3D check would have to pass the 2D check)
 
Thanks,
Regina

________________________________

From: postgis-users-bounces at postgis.refractions.net
[mailto:postgis-users-bounces at postgis.refractions.net] On Behalf Of
eehab hamzeh
Sent: Thursday, September 18, 2008 5:41 AM
To: Kevin Neufeld; PostGIS Users Discussion
Subject: RE: [postgis-users] make the buffer in 3d


Kevin, 

Thank you, i need to:

1) create buffer in 3d. I mean the resulted buffer should have z value.
the z value will be equal to the radius value.


2) select all features that are intersect this cylinder, or inside this
cylinder.

Thanks 





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