Brent, The key when binning is to ensure that your rows are not larger than the page size (8KB). If we say your 3D points take 25 bytes (3 doubles plus type overhead), then the actual max number of points in a patch would be 327. From that subtract size for other attributes you might be carrying.
P. On Tue, May 5, 2009 at 9:22 PM, <[email protected]> wrote: > > > Thanks for the suggestions, much appreciated as always!! > > > That sounds interesting. I'm currently storing XY points in a 2d geometry, > with a separate depth column. I could convert these to 3D points to retain > the z value of each point when stored as a multipoint. > > I have not used 3D geometries before, so a quick followup to ask about any > caveats or advice you may have to offer on this approach, basically > generating the 3D points, then using Kevin's approach to binning these say > every 0.5 degrees. > > Does ST_SnapToGrid work on 3D geometries? I only want them snapped by XY, not > Z. > > My Z units are m, my X&Y are degrees. Any issues there? > > I assume any transform() operations will simply pass through the Z value > unchanged? > > > Thanks, > > Brent Wood > > > > --- On Wed, 5/6/09, Kevin Neufeld <[email protected]> wrote: > >> From: Kevin Neufeld <[email protected]> >> Subject: Re: [postgis-users] value of spatial index on 300, 000, 000 point >> geometries >> To: "PostGIS Users Discussion" <[email protected]> >> Date: Wednesday, May 6, 2009, 2:06 PM >> Yes, I had to store a table of 3D DEM >> point data (~170million) in a >> database once. As Paul mentioned, there >> can be great benefits of >> grouping your points into multipoint objects. >> Consider that if you >> convert your points into groups of 200, the index could be >> up to 200 >> times smaller. > > > _______________________________________________ > postgis-users mailing list > [email protected] > http://postgis.refractions.net/mailman/listinfo/postgis-users > _______________________________________________ postgis-users mailing list [email protected] http://postgis.refractions.net/mailman/listinfo/postgis-users
