Motivation of Motion Planning
   - Robotic motion planning, joints and paths.
   - Maintainability studies (separating parts.)
   - Digital Actors
Why focus on Narrow Passages
   - Computing explicit C-space feasible only up to 3-4 dimensions.
   - Randomized planners don't cover narrow passages well.
   - Want to improve upon existing techniques:
       - Dilating Free Space.
       - Sampling Based on Medial Axis
       - Sampling near obstacle boundaries.
       - ** Need analogy between WS and CS.
Overview of Algorithm
   - Efficient - Fast medial axis computation, and QR from distance buffer.
   - Simplicity - PRM's are simple and we only modify the sampling technique.
   - Narrow passage identification
   - Can use gradient to align robots principle axis for biased sampling.
   - Based on a heuristic identify some areas to be narrow, and increase samples.
   - Global connectivity information - most others don't use.