Thilo Hannemann schrieb:
Here is another approach to the "lost last point". The Douglas Peucker filter is improved so that it can deal with identical start- and endpoints. If the start- and the endpoint are identical, the algorithm calculates the distance between these identical points and the point p. So the polygon is not split at point N/2, but at the point that has the greatest distance from the start-/endpoint.
Dealing with the problem in the Douglas Peucker algorithm itself has the advantage that it will also work for a pathological polygon or way that has identical, non-consecutive points in the middle of it.
Hi Thilo, I was just trying to get your patch working and would like to test it afterwards. In general I find it a good one. But I'm not sure about the last lines of your patch. If you delete the endpoint in case of ab==0 then you introduce the original problem again. The problem was polygons loosing their start or endpoints. What are your thoughts about it? Greetings, Johann
@@ -148,6 +154,12 @@ } else { // All points in tolerance, delete all of them. + + // Remove the endpoint if it is the same as the startpoint + if (ab == 0) + points.remove(endIndex); + + // Remove the points in between for(int i = endIndex-1; i > startIndex; i--) { points.remove(i); }