Optimally smooth error resilient streaming of 3D wireframe animations

Much research has been undertaken in the area of streaming video across computer networks in general and the Internet in particular, but relatively little has been undertaken in the field of streaming 3-D wireframe animation. Despite superficial similarities, both being visual media, the two are significantly different. Different data passes across the network so loss affects signal reconstruction differently. Regrettably, the perceptual effects of such loss have been poorly addressed in the context of animation to date and much of the work that there has been in this field has relied on objective measures such as PSNR in lieu of those that take subjective effects into account. In this paper, we bring together concepts from a number of fields to address the problem of how to achieve optimal resilience to errors in terms of the perceptual effect at the receiver. To achieve this, we partition the animation stream into a number of layers and apply Reed-Solomon (RS) forward error correction (FEC) codes to each layer independently and in such a way as to maintain the same overall bitrate whilst minimizing the perceptual effects of error, as measured by a distortion metric derived from related work in the area of static 3-D mesh compression. Experimental results show the efficacy of our proposed scheme under varying network bandwidth and loss conditions for different layer partitionings. The results indicate that with the proposed Unequal Error Protection (UEP) combined with Error Concealment (EC) and efficient packetization scheme, we can achieve graceful degradation of streamed animations at higher packet loss rates than other approaches that do not cater for the visual importance of the layers and use only objective layering metrics. Our experiments also demonstrate how to tune the packetization parameters in order to achieve efficient layering with respect to the subjective metric of surface smoothness.