Make area generation more robust Valid geometries can become invalid geometries during transformation e.g. due to very small 'minimum clearance' (see PostGIS docs) and numerical inaccuracy of the transformation. Thus, try to repair polygons of the input area after transformation and calculate the union of the result polygons before transformation to avoid 'TopologyException' in the union operations. The simulated waterway area of the changed axis in the test data is affected here, but real waterway area data with complex shore lines could likely be affected, too.

teichmann@intevation.de = sascha.teichmann@intevation.de
bernhard.reiter@intevation.de = bernhard@intevation.de