The existing geodesic distance transform algorithms consider the influence of obstacles

but the calculated distances have errors. A bruteforce algorithm is suggested for accurate geodesic distance transform in a space with obstacles in this paper. It takes the convex corners on obstacles as relay sources to calculate the length of the shortest passable path from foreground pixels to background pixels behind the obstacles. The relay sources of this algorithm lie on the shortest passable paths from foreground pixels to background pixels

and thus distance errors are avoided

better than other relay sources suggested in the existing geodesic distance transform algorithms. Experimental results show that there is no distance error in the new algorithm

and it is applicable for distance transform in space with obstacles in any shapes.