1. Forcibly symmetrize the neighbor relations, so that if A is neighbor of B, B is neighbor of A. The existing code is guaranteed to violate this if texture resolution is different between the sides of a seam. 2. In texture mode dynamic paint adds a 1 pixel wide border around the islands. These pixels aren't really part of the dynamic paint domain and thus by design can't have symmetrical neighbor relations. This means they can't be treated by effects like normal pixels. The simplest way to handle it in a consistent way is to exclude them from effects, but add an additional pass that recomputes them as average of their non-border neighbors, located on both sides of the seam.