A rate-distortion optimal scalable vertex based shape coding algorithm
We present a rate-distortion (RD) optimized scalable vertex-based shape coding algorithm. Following the base layer, each successive enhancement layer refines a given shape approximation by optimally (within a layer) placing new vertices and perturbing existing vertices. An efficient low entropy distortion adaptive vertex coding strategy is employed to take advantage of information available from coarser layers. Based on the chosen vertex rate and distortion definitions, a resulting enhancement layer topology is solved by executing a directed acyclic graph (DAG) shortest path algorithm. Finally, an iterative VLC optimization scheme is employed to find both the optimized scalable code and the most efficient set of parameter VLC tables.