3D Graphics Standardization in MPEG-4

Computer graphics is currently the spine of several industries of information technology. From computer aided design of almost all objects surrounding us, through virtualization of 3D environments such as Google Earth, to video games, 3D graphics becomes a valuable media with a similar impact as the one of video, image and audio. Such digital assets should be exchanged between producers, service providers, network providers and device manufacturers. Supporting large-scale interoperability needs the development and deployment of open standards. ISOa, as a major international standardization organization, anticipated this issue and proposed in the last decade several standards addressing 3D graphics assets exchange. VRML (ISO, 1997) (Virtual Reality Modeling Language), published in 1997, provides basic geometry primitives, appearance models and animation mechanisms for representing 3D objects and scenes. Built on top of VRML, the first version of MPEG-4 (ISO, 1998) supports tools for the compression and streaming of graphics assets. Since then, MPEG improved the 3D graphics compression technologies and published the MPEG-4 Part 16 (ISO, 2004) in order to address theses issues within a unified and generic framework. This chapter is dedicated to professionals of 3D graphics industry, solution providers for on-line systems involving 3D content (games, persistent universes, virtual spaces with graphical representation), students and professors in digital sciences. The first section aims at presenting the background of the compression for multimedia signals. The second section presents the latest developments in MPEG-4 with respect to the compression and streaming of 3D graphics objects and scenes. The MPEG-4 tools, categorized into geometry, appearance and animation, are introduced. While MPEG standards specify only the bit-stream syntax and the architecture of the decoder, scheme for encoders’ implementation are presented in this section. In the third section we describe a recently adopted MPEG model for 3D graphics consisting in opening the representation of graphics primitives to any XML-based format and completing it with binarization and compression layers. This shift in the manner of using MPEG-4 for 3D graphics is concretized in Part 25 of MPEG-4 (Preda, Jovanova, Arsov& Prêteux, 2007).