Hi Gerd / anyone else Attempting to improve filtering by considering their optimal order, I got much worse results at very low resolutions. The excess was lots of 1-res-unit lines (these came from the coastlines of lots of small islands) These lines start off sufficiently large to make it through the sizeFilter. Running the DP filter next, if intermediate points are less than - -reduce-point-density (default 2.6) res-units from the line between first and last point, they are dropped. This can result in a single point if the first and last points are equal, or a line shorter than at least 2 of the sub-lines that no longer exist. I'm not sure of the best approach to deal with this. I considered inhibiting DP if the distance between start&end (either overall or for the internal sub-processing) is less than the error distance, but this is wrong for polygons or lines that loop back towards their starting point. Maybe the DP error size must be less than sizeFilter size; For lines this is MIN_LINE_SIZE = 1 and not configurable, For polygons it is --min-size-polygon (default 8) or --polygon-size-limits. Running RemoveObsoleteFilter before or after DP effects the final result. Considering the functions of the filters, I think RemoveObsolete should be before DP; DP shouldn't produce obsolete points and there is no point in DP considering obsolete points. Ticker