[postgis-users] ST_Raster question, Use spot heights and create an Elevation raster layer

[Simon Greener]

Pierre,

>> What I wish to now do is to use those spot heights to create an elevation raster
>> layer via which all NoDataValued pixels have an elevation set that is interpreted
>> from the spot heights around it.
>>
>> Has anyone any suggestions as to how this can be done by PostGIS's ST_Raster?
>> (ST_MapAlgebra perhaps etc?)
>
> We don't have any interpolation algorithm yet. But we have ST_MapAlgebraFctNgb() which compute pixels value as focal functions (or moving windows). I not sure to which degree you can implement interpolation with moving windows but if your points are close to each other enough you could compute the mean of the point surrounding each point. Have a look at:
>
> http://postgis.refractions.net/documentation/manual-svn/RT_ST_MapAlgebraFctNgb.html

Thanks for answering and the pointer to the MapAlgebra function. Unfortunately I can't see how
to create an interpreted elevation surface all that easily using the current vector and raster
tool sets. Such an ability, native to raster itself, would be very, very useful but I can understand
how difficult it is to create one as part of an open source project.

If anyone else can provide pointers to a solution, I would appreciate it.

regards
Simon
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