[postgis-users] 3D topology nodes?

[Sandro Santilli]

On Fri, Jun 01, 2012 at 08:18:02PM -0400, John Morrison wrote:

> (1) Performance (or lack thereof): I am attempting to create topology
> out of a rather large (36MPixel) SRTM elevation raster.  I am
> currently using a very small tile as the processing times I am seeing
> suggest using a calendar rather than a stopwatch to profile my code.
> Is there some obvious thing I should be doing to speed things up?
> Perhaps something analogous to how raster2pgsql emits an SQL file
> rather than doing a pixel-at-a-time update?  Or perhaps I am going
> about this entirely the wrong way?  (I had similar performance
> problems in simply reading the raster out of PostGIS, but that was
> more straightforward to work around...)

You're probably doing nothing wrong, and topology building is known
to be slow. Showing how you did it would give us more informations,
but again, we know it's slow. Your help in profiling might help
speeding things up. Patches are also very welcome.

> (2) Are there any "gotchas" of which I should be aware due to "no
> proper 3D topology support?"  False co-planarity issues?  Limitations
> to modeling road overpasses, etc?

No road overpass, no vertical lines, false co-planarity.

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