Limitations

Known Limitations

• Some polygon normals sometimes get inverted. Usually a (wrong) normal is preserved from the data set, but in rare instances a bug may cause a correct normal to be inverted (and the other way around--in that case it's a feature!).
• Non-building thematic classes are not supported in the semantic sense (they will be converted together as Other class). However, all geometry will be converted to the plain OBJ regardless of the theme, when the corresponding option is invoked).
• The texture from the CityGML is not converted to OBJ (future work).
• The tool supports only single-LOD files. If you load a multi-LOD file, you'll get their union.
• If the converter crashes, it's probably because your CityGML files contain invalid geometries. Run the code with the -v 1 flag to validate and skip the invalid geometries. If that doesn't work, try to invoke the option -p 1. If that fails too, please report the error.
• XLink is not supported, nor will be because for most files it will result in duplicate geometry.
• The tool does not support non-convex polygons in the interior, for which might happen that the centroid of a hole is outside the hole, messing up the triangulation.
• Skipping triangulation does not work with polygons with holes.
• Skipping the triangulation will cause incorrect representation of non-convex polygons
• There can be issues for non convex holes. At the moment, the centroid of the polygon that describes the hole is used as a reference point for the hole. It is however not guaranteed that the centroid is inside of a polygon if it is not convex. Alternatively, a point inside the polygon could be identified with a designated shapely function. While this works in most cases, it is going to lead to issues for some datasets.
• The paralleliszation can sometimes fail for large datasets.