We present Roadmap Sparsification by Edge Contraction (RSEC), a simple and effective algorithm for reducing the size of a motion-planning roadmap. The algorithm exhibits minimal effect on the quality of paths that can be extracted from the new roadmap. The primitive operation used by RSEC is edge contraction – the contraction of a roadmap edge to a single vertex and the connection of the new vertex to the neighboring vertices of the contracted edge. For certain scenarios, we compress more than 98% of the edges and vertices at the cost of degradation of average shortest path length by at most 2%.
Edge Contraction: Graph before (left) and after (right) the contraction of the
edge (v3, v4) to the point v34. Obstacle is depicted by the green triangle.
Roadmap example before and after RSEC*:
* Scenario provided with the OMPL distribution.