PNG: The Definitive Guide

Chapter 6. Applications: VRML Browsers and Other 3D Apps

VRML, the Virtual Reality Modeling Language, is a file format and a language for defining three-dimensional virtual objects, their appearances and their behaviors. As of early 1999, it has seen two major versions, and the design of a third is currently underway. Version 1.0 included little more than static geometry and never saw wide use. Version 2.0, released in August 1996 and approved as an ISO/IEC international standard in December 1997, added animation, scripting, and a much more rigorous specification of all aspects of the format. It also mandated PNG as one of two image formats required for minimal conformance. (JPEG was the other.) No doubt due to PNG's rampant popularity, [39] VRML 2.0--or VRML97, as the ISO standard is known--achieved dramatically greater recognition and acceptance than VRML 1.0, with shipments of VRML97 browsers reaching levels of between 25 million and 75 million units by the autumn of 1998.

How is PNG actually used in a 3D, text-based file format? A complete answer would require considerable discussion of 3D rendering engines, CPU and memory performance, Moore's Law, and so forth. But in a nutshell, VRML is designed for interactive 3D--particularly Web-based, immersive, interactive 3D. A truly realistic animated object, such as the dinosaurs in the movie “Jurassic Park” or the flying cow in “Twister,” would require far more computational power to render in “real time” at reasonable frame rates ...