Approximating the Maximum Overlap of Polygons under Translation
  Let $P$ and $Q$ be two simple polygons in the plane of total complexity $n$, each of which can be decomposed into at most $k$ convex parts. We present an $(1-\varepsilon)$-approximation algorithm, for finding the translation of $Q$, which maximizes its area of overlap with $P$. Our algorithm runs in $O(c n)$ time, where $c$ is a constant that depends only on $k$ and $\varepsilon$.   This suggest that for polygons that are "close" to being convex, the problem can be solved (approximately), in near linear time. 
Sariel Har-Peled and Subhro Roy
cs.CG