Slow performance due to invalid polygons about 3dfier

[hugoledoux]

We should, but then what do we do with them? Discard them? Warn user?

[tcommandeur]

A error it thrown in the current version.

if (!geometry->IsValid()) {
std::cerr << "Geometry invalid: " << f->GetFieldAsString(idfield) << std::endl;
}

[grivy]

I'm not sure at which point during the conversion the invalid geometries occur, but I think you can safely assume that the BGT geometries are valid. There is one possible exception though which is where 1 vertex of an interior ring crosses the exterior ring by less than 0.5mm. This occurs very rarely (I have seen only two which have been fixed now).
You should however make sure when converting arcs to line segments that the density is high enough to not create self-intersections. BGT geometries are robust in that a 0.5mm threshold is used, so set the densify parameters accordingly.

[tcommandeur]

The invalid geometries occurred due to broken shapefiles, code throws an error to notify.

About converting arcs to line segments, this is not as easy as stated. to be able to discretise lines topologically correct a robust arc-reversible algorithm needs to be used like GDAL which is not that easy to influence.