[postgis-users] TIN from point coverage

[Olivier Courtin]

On Mar 24, 2011, at 10:52 PM, Pierre Racine wrote:

Pierre,

> My goal is to define the way leading from a point coverage to a  
> raster. Something like ST_Interpolate("pointgeomtable",  
> "rastercolumn") -> raster. What would be the step leading to that?
>
> I guess we have everything now to store a Delaunay Triangulation as  
> polyhedral surfaces right?

Hum yes and no, in fact it depends :)

As i said the TIN model is designed for a feature model storage (CIM  
use case),
so in a single cell, a reasonable small TIN (i.e thousands of points  
is fine
or even more, but not a whole LIDAR Coverage triangulation)

If we want to handle this use case, i think
we have to add a way to split and aggregate a big TIN into several  
small ones
(as i recall it should be the way Oracle Spatial handle it)


> Then from this polyhedral surface we can derive a raster...
>
> Maybe a first ST_AsDelaunayTriangulation(geom) could be an aggregate  
> SET function returning a set of triangle...

Yes, if you produce a set of Triangles rather than a single huge TIN,
it could works with the current TIN implementation.

Question: is it something liblas could already handle ?

> and maybe ST_Interpolate(polyhedral surfaces) could be an aggregate  
> function that would aggregate those triangle into a raster?



--
Olivier