[gdal-dev] ogr2ogr -tps with more than 1000 control points

[Even Rouault]

On vendredi 9 août 2019 13:31:57 CEST Jan Hartmann wrote:
> Hi all,
> 
> I'm converting large historical vector maps with ogr2ogr, using -gcp and
> -tps to rubbersheet the polygons with control points. Works fine up to
> about a thousand control points, each in the form of "-gcp fromx fromy
> tox toy". After that, the converted map becomes erratic. Is this a bug?

Two hypothesis:
- the extra GCP you're adding are wrong
- there's numerical instability in the matrix computations with the extra GCP. 
If your GDAL build doesn't use libarmadillo, then consider rebuilding against 
it, as it might improve numeric stability.

Even

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