[gdal-dev] 3D TIN support in WKBs

[Gergely Czuczy]

On 14/03/2015 05:35, Even Rouault wrote:
> Selon Gergely Czuczy <gergely.czuczy at harmless.hu>:
>
>> Hello,
>>
>> I would like to ask whether there's any support for reading 3D TIN data
>> from WKBs, and if so, how can I do this?
>>
>> Currently when I try to read the following's WKB:
>> TIN Z (((512 -512 0,512 512 0,-512 -512 0,512 -512 0)),((512 512 0,512
>> -512 0,-512 -512 0,512 512 0)))
>> I get the error message:
>> ERROR 6: Unsupported WKB type 1016
>> ERROR 3: OGR Error: Unsupported geometry type
>>
>> I would like to read TINZ data from PostGIS into C++ and Python
>> programs, however there doesn't seem to be many libraries that support this.
>>
>> So, how can I read such 3D TINs using GDAL?
> Gergely,
>
> There's no support in GDAL for TIN. If you would want to implement it, you could
> take inspiration of what has been done recently to support curve geometries.
> Reading http://trac.osgeo.org/gdal/wiki/rfc49_curve_geometries should direct you
> at the places to modify.
>
> If you want to take a shorter route, you could just parse the WKB/WKT returned
> by PostGIS at your application side.
>
> Even
Thank you for your reply. To be honest I would like to focus on my pet 
project, and probably you could find better people with 3D/graphics 
coding experience than me. That's one of the reasons why I am looking 
for some library to do the heavy lifting instead of me.

Could you please give me some pointers on how to parse a WKB/WKT? 
Especially the float representation in the WKB I'm interested in. I 
think I will try to parse it myself.

After that, if I parse it manually, can I construct a gdal object out of 
it for manipulation, and at the end export it again to one or more TINZs 
for propagating it back into postgis?

Gergely