[postgis-users] TIN from point coverage

[Stefan Keller]

2011/3/24 Olivier Courtin <olivier.courtin at oslandia.com> wrote:

Interesting discussion and use cases.

Oracle seems to offer two structure, one for TIN and one for Point
Cloud, which I find reasonable
(see TIN: http://download.oracle.com/docs/cd/B28359_01/appdev.111/b28400/sdo_objrelschema.htm#CBBFDFCJ
and Point Cloud:
http://download.oracle.com/docs/cd/B28359_01/appdev.111/b28400/sdo_objrelschema.htm#insertedID6
)

=> Where is the docu. for TIN in PostGIS?

There is no Point Cloud data type yet in PostGIS and Paul told me that
there are no plans to implement this yet as described here
http://opengeo.org/technology/postgis/coredevelopment/pointclouds/ .
=> Still holds true?

Yours, Stefan


2011/3/24 Olivier Courtin <olivier.courtin at oslandia.com>:
>
> 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
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