Computing the Fr\'{e}chet Distance Between Folded Polygons
  Computing the Fr\'{e}chet distance for surfaces is a surprisingly hard problem and the only known algorithm is limited to computing it between flat surfaces. We adapt this algorithm to create one for computing the Fr\'{e}chet distance for a class of non-flat surfaces which we call folded polygons. Unfortunately, the original algorithm cannot be extended directly. We present three different methods to adapt it. The first of which is a fixed-parameter tractable algorithm. The second is a polynomial-time approximation algorithm. Finally, we present a restricted class of folded polygons for which we can compute the Fr\'{e}chet distance in polynomial time. 
Atlas F. Cook IV, Anne Driemel, Sariel Har-Peled, Jessica Sherette,   Carola Wenk
cs.CG