Reduce number of points in line

Question

I\'m searching for algorithms to reduce the LOD of polylines, lines (looped or not) of nodes. In simple words, I want to take hi-resolution coastline data and be able to re

Answer 1

I'm a fan of sorting the points based on the angle that the segments make on either side of the point, then removing the points with the shallowest angle iteratively until you hit some threshold. O(n log(n)) I think, versus the RDP method's O(n^2), and with smaller constants to boot. :)

The angle can even be scaled by the segment lengths (indeed it's easier to compute it this way) if you want to give more weight (desirability) to longer segments.

Given p0, p1, p2, p1's weight would be ((p0 - p1) dot (p2 - p1)), normalize the differences if you don't want to weight by length. (Contrast this to distance-to-line, it is much cheaper, and the results may be identical.)