Extending Progressive Meshes for Use over Unreliable Networks
Zhihua Chen, Bobby Bodenheimer, and J. Fritz Barnes
Abstract
Progressive meshes (PMs) provide an attractive mechanism for transmitting 3D
geometry over networks. Progressive meshes transmit a coarse
initial mesh and refinements that can be applied to the initial mesh.
However, these techniques assume a reliable network protocol such as
TCP/IP is used for data transmission. When transmitting 3D geometry
for graphical applications such as concurrent virtual environments
distributed over wide area networks with some nodes potentially using
wireless networks, many losses will occur. TCP/IP performance
degrades in the presence of packet loss and multicast communication
mechanisms typically do not provide reliable communication. These
applications motivate the issue of transmitting geometric data over
unreliable networks. In this paper, we discuss several errors that
are caused when reconstructing PM geometries after some packets have
been lost. We modify the PM data structures to improve robustness
during packet loss. We use these modifications to improve a hybrid
transmission technique that uses TCP to transmit the base mesh and
portion of the initial mesh and then use UDP to transmit the remainder
of the mesh to improve transmission performance.
Bobby Bodenheimer 
Last modified: Wed Jun 25 13:39:06 CDT 2003