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Introduction to COLLADA
 COLLADA: An Industry Open Standard
An important announcement at SIGGRAPH ’05 was that the Khronos Group had accepted COLLADA as an industry standard [32], along with OpenGL ES and several other real-time APIs. This was a very important step for COLLADA since its specification had been ratified by the Khronos Group promoters, a significant group of companies, and had finally reached an official industry-standard status.
COLLADA now has a life of its own (and will survive even if the original partners change their minds in the future), providing the stability that is necessary for the majority of developers, tool vendors, and middleware companies to invest in it. In addition, the Khronos Group provides the necessary IP protection, since ratification from the Khronos Group means that all the members have agreed that COLLADA did not infringe on any IP they owned, or, if that was the case, they agreed to provide an IP license to anyone using COLLADA.
Getting COLLADA to be accepted by the Khronos Group was no easy task. The major difficulty was that COLLADA was not an API, and the Khronos Group had only dealt with APIs in the past. Much convincing was necessary for the members to accept that common APIs were not enough, but that they also had to make sure that content was available in a standard format.
On the other hand, the original partners were balancing the benefit of having COLLADA as a formalized open standard, with the perception that SCE was abandoning the project to the Khronos Group. Because of this, SCE decided to become a Promoter member of Khronos, the highest rank of partnership. This was necessary for SCE to affirm their continuous involvement in the project, which was key in its development.
Only two years after the project started, and one year after being publicly announced, COLLADA partners were successful in creating an industry standard targeted for the entertainment industry.
The authors want to thank all the partners and congratulate them for this exceptional result.
Notes and References
[1] The authors received an e-mail from a Lead Systems Engineer on a US Army simulator program mentioning their interest to use COLLADA as a database format.
[2] The Lunar Module Mission Simulator was used at the Kennedy Space Center between 1968 and 1972. It was used by every Apollo astronaut to train prior to their mission. Cameras controlled by a computer, filming a model of the lunar surface, projected the image in front of the four windows so the astronauts would feel as if they were actually maneuvering for a landing on the Moon. In this early real-time image generator, the database was in hardware!
[3] There are over 700 bibliographic references on ray-tracing techniques. Andrew S. Glassner’s book, An Introduction to Ray Tracing, first published in 1989 by Morgan Kaufmann is a good reference book. PovRay (Persistence of Vision Raytracer) is a free ray-tracing tool available for many platforms and also in source code (http://www.povray.org/).
[4] Pixar Animation Studios created the RenderMan rendering technology to generate their own feature film productions. Since its introduction in the 1990s, it has become a standard tool in many computer graphics studios (http://renderman.pixar.com/).
[5] Computer-aided design (CAD) is a very large market. Originally created for the automobile and the aerospace industries, these DCC tools are now ubiquitous in the manufacturing industry. Pierre Bézier, a French mathematician who died November 25, 1999, was one of the early pioneers. While working at Renault, a French automaker, he invented a method of describing any 2nd degree curve using only four points, which is now referred to as the Bézier curve.
[6] General Electric was a pioneer in terrain paging capability for their IMAGE series. Terrain paging is a complex feature that requires specific hardware such as direct DMA engines from disk to main memory and fast disk array systems. A lot of information on terrain paging and related algorithms can be found on the World Wide Web (http://www.vterrain.org/).
[7] Christopher C. Tanner, Christopher J. Migdal, and Michael T. Jones. “The Clipmap: A Virtual Mipmap.’’ In Proceedings of SIGGRAPH 98, Computer Graphics Proceedings, Annual Conference Series, edited by Michael Cohen, pp. 151–242, Reading, MA: Addison Wesley, 1998.
[8] In complexity theory, the NP-complete problems are the most difficult problems in NP (nondeterministic polynomial time).
[9] Google Earth lets you browse the Earth from your computer, paging both terrain and satellite images in real time from the Internet. It is freely available (http://earth.google.com/).
[10] Christopher Tanner and Rémi Arnaud created a prototype of this technology as a demonstration when looking for venture money to finance the Intrinsic Graphics start-up. Once Intrinsic Graphics was financed, it focused on middleware for the game market. The original technology was so compelling that Keyhole was created as a separate entity to create a product. This company was later bought by Google, and the product became Google Earth.
[11] Iris Performer, a very popular scene graph, was developed at Silicon Graphics and is still in use today. J. Rohlf and J. Helman. “IRIS Performer: A High Performance Multiprocessing Toolkit for Real-Time 3D Graphics.” In Proceedings of SIGGRAPH 94, Computer Graphics Proceedings, Annual Conference Series, edited by Andrew Glassner. pp. 381—395, New York: ACM Press, 1994. OpenSceneGraph was first created as an open-source equivalent, since Performer was originally not available on any other platform than the SGI computer. Industry-standard database formats, such as Multigen OpenFlight, were created and are still in use today in the simulation industry.
[12] Binary space partition (BSP) trees were first used in the early flight simulators’ visual systems to determine a hidden part removal algorithm. The idea is to determine the drawing order of all the geometry so that the hidden parts are covered by the visible parts. Also known as the painter’s algorithm, this was used in early 3D games before the hardware accelerated Z-buffer was widely available in graphics hardware accelerators.
[13] DotXSI and the FTK (File Transfer Toolkit) were created by Softimage (http://softimage.com/products/xsi/pipeline_tools/dot_xsi_format/).
[14] Historical information on the creation of OpenGL and DirectX can be found on Wikipedia (http://en.wikipedia.org/wiki/Opengl#History) (http://en.wikipedia.org/wiki/Direct_x#History).
[15] The name COLLADA was coined by the engineers in R&D, since several projects had code names that were named after winds. A collada is a strong north or northwest wind blowing in the upper part of the Gulf of California, but blowing from northeast in the lower part of the Gulf. The acronym COLLAborative Design Activity was then created by Attila Vass, senior manager in the SCE US R&D department.
[16] Unfortunately, this relies on the capability of the DCC tools to be flexible enough to store the extra data in their internal representation. A discussion on this project is available on the World Wide Web (https://collada.org/public_forum/viewtopic.php?t=312).
[17] Criterion has since been acquired by Electronic Arts. EA has made RenderWare their main tool. Although the product was still available as a middleware on the market, the loss of independence rapidly impacted their ability to sell.
The other game developers could not afford to depend on their competitor’s technology.
[18] Vicarious Vision was later purchased by Activision, eliminating another independent middleware vendor.
[19] The Emdigo website (http://www.emdigo.com/).
[20] AGEIA acquired Novodex in 2004, which gave them the PhysX SDK. In September 2005, they acquired Meqon Research AB, consolidating the market for the physics engine for game development.
[21] Discreet and Autodesk offer a wide range of products for the media and entertainment market (http://www.discreet.com/) (http://www.autodesk.com/).
[22] Alias had been owned by Silicon Graphics, Inc. since 1995. It was acquired by Accel-KKR, an equity investment firm, for $57M in April 2004. It was sold back to Autodesk in January 2006 for $197M. Autodesk now has both 3ds Max and Maya DCC tools, representing close to 80% of the tools used in the game industry (http://www.alias.com/) (http://www.autodesk.com/).
[23] Softimage, an Avid company, is the maker of the XSI DCC tool (http://www.softimage.com/) (http://www.avid.com/).
[24] R. Arnaud, M. Barnes. “COLLADA: An Open Interchange File Format for the Interactive 3D Industry.” SIGGRAPH ’04 Exhibitor Tech Talk, 2004.
[25] X3D has also decided to use XML as the base technology (http://www.web3d.org/). Unfortunately, X3D design is not very popular among game developers, since it was designed for a different domain of application: 3D for the Web. Later on, the X3D community created a document that shows that the two designs are very different (http://realism.com/Web3D/Collada/Nodes).
[26] COLLADA 1.1 was published in December 2003. COLLADA 1.2 was published in January 2004 as a patch release. COLLADA 1.3 was released in March 2005, introducing only a few features such as skinning but improving the conformance test and the quality of plug-ins. There was a COLLADA 1.3.1 patch release in August 2005. The specification stayed quite stable between 1.1 and 1.3.1, waiting for DCC vendors to create quality tools and developers to start using the technology. All those releases were done under an SCE copyright and licensing. COLLADA 1.4 was released in January 2006 under the Khronos umbrella, introducing major features such as COLLADA FX , COLLADA Physics, and a new design philosophy based on strong typing. Once again, the specification is in a stable phase, waiting for good implementations to be available. With the additional interest from developers, the cycle will be much shorter this time.
[27] ATI website (http://www.ati.com/).
[28] NVIDIA website (http://www.nvidia.com/).
[29] 3Dlabs website (http://www.3dlabs.com/). In February 2006, 3Dlabs decided to drop their desktop division and concentrate on the mobile embedded market space.
[30] Nokia website (http://www.nokia.com/).
[31] At the 2005 PlayStation press conference, Masami Chatani (CTO) announced that the PS3’s development environment will support COLLADA. This raised the interest in COLLADA from game developers.
[32] Khronos Group. “COLLADA Approved by the Khronos Group as Open Standard.” Press Release, July 29, 2005 (http://www.scei.co.jp/corporate/release/pdf/050729e.pdf).
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