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Standard Procedural Databases

You can download the latest version of the SPD (currently 3.14), and also view the original IEEE CG&A article from Nov. 1987. This software package is not copyrighted and can be used freely (for example, WCT2POV, a good 3D file converter for Windows, uses SPD's libvec.c graphics library). All source is in K&R vanilla C (though ANSI headers can be enabled) and has been used on many systems. A MacOS version can be found on Eduard Schwan's SPD page.

For a newer set of more realistic environments for benchmarking ray tracers (or renderers in general), see BART: A Benchmark for Animated Ray Tracing. The focus is software that generates an animated set of frames for a ray tracer to render. These scenes use an NFF-like language (AFF), and the authors provide a number of tools for parsing and visualization.

This software is meant to act as a set of basic test images for ray tracing algorithms. The programs generate databases of objects which are fairly familiar and "standard" to the graphics community, such as the teapot, a fractal mountain, a tree, a recursively built tetrahedral structure, etc. I originally created them for my own testing of ray tracing efficiency schemes. Since their first release other researchers have used them to test new algorithms. In this way, research on algorithmic improvements can be compared in a more standardized fashion. If one researcher ray-traces a car, another a tree, the question arises, "How many cars to the tree?" With these databases we may be comparing oranges and apples, but it's better than comparing oranges and orangutans. Using these statistics along with the same scenes allows us to compare results in a more meaningful way.

Another interesting use for the SPD has been noted: debugging. By comparing the images and the statistics with the output of your own ray tracer, you can detect program errors. For example, "mount" is useful for checking if refraction rays are generated correctly, and "balls" (a.k.a. "sphereflake") can check for the correctness of eye and reflection rays.

The images for these databases and other information about them can be found in A Proposal for Standard Graphics Environments, IEEE Computer Graphics and Applications, vol. 7, no. 11, November 1987, pp. 3-5. See IEEE CG&A, vol. 8, no. 1, January 1988, p. 18 for the correct image of the tree database (the only difference is that the sky is blue, not orange). The teapot database was added later.

The Neutral File Format (NFF) is the default output format from SPD programs. This format is trivial to parse (if you can use sscanf, you can parse it), and each type of object is defined in human terms (e.g. a cone is defined by two endpoints and radii). The basic shapes supported are polygon and polygon patch (normal per vertex), cylinder, cone, and sphere. Note that there are primitives supported within the SPD which are not part of NFF, e.g. heightfield, NURBS, and torus, so more elaborate programs can be written. If a format does not support a given primitive, the primitive is tessellated and output as polygons.

Ares Lagae has written libnff, a modern C++ library for parsing NFF that also supports conversion to Wavefront OBJ.

Other output formats are supported:

  • POV-Ray 1.0
  • POV-Ray 2.0 to 2.2
  • POV-Ray 3.1
  • Polyray 1.4 to 1.6
  • Vivid 2.0
  • QRT 1.5
  • Rayshade 4.0.6
  • RTrace 8.0.0
  • Art 2.3 (from Vort)
  • RenderMan RIB
  • AutoCAD DXF [object data only]
  • Wavefront OBJ format (polygons only)
  • RenderWare RWX script file
  • Apple 3DMF
  • VRML 1.0
  • VRML 2.0

Alexander Enzmann receives most of the credit for creating the various file format output routines, along with many others who contributed.

There are also reader programs for the various formats. Currently the following formats can be read and converted:

  • NFF
  • DXF (just 3DFACEs)
  • OBJ

This makes the NFF format a nice, simple language for quickly creating models (whether by hand or by program), as any NFF file can be converted to many different formats. Warnings:

  • The conversions tend to be verbose in many cases (e.g. there is currently no code in place to group polygons of the same material into polygon mesh primitives used in some formats).
  • No real tessellation of polygons is done when needed for conversion, all that happens are that polygon fans are created.
  • You might find the images you obtain are mirror reversed with some formats (e.g. VRML 2.0 files).

The Graphics Gems V code distribution has a simple z-buffer renderer by Raghu Karinthi, using NFF as the input language.

On hashing: a sore point in mount.c, the fractal mountain generator, has been its hashing function. Mark VandeWettering has provided a great hashing function by Bob Jenkins. To show what a difference it makes, check out images of models made with the original hash function with a large size factor, replacement hash function I wrote (still no cigar), and Jenkins' hash function.

For more information on the SPD, see the README.txt file included in the distribution.

For 9.5 million of you out there: a Belarusian translation of this page by Michail Bogdanov.

Compatibility Notes


On some (all?) versions of gcc on Linux, the following correction to the code is necessary:

libinf.c, line 33:

FILE *gOutfile = stdout;
change to
FILE *gOutfile = NULL;

Research Works using SPD

Timing comparisons for the various scenes using a wide variety of free software ray tracers are summarized in The Ray Tracing News, 3(1) (many), 6(2), 6(3), 8(3), and 10(3). Here are some research works which have used the SPD to benchmark their ray tracers (please let me know of others; you can always search Google Scholar for more):

  • Kay, Timothy L. and James T. Kajiya, "Ray Tracing Complex Scenes," Computer Graphics (SIGGRAPH '86 Proceedings), 20(4), Aug. 1986, p. 269-78.
  • Arvo, James and David Kirk, "Fast Ray Tracing by Ray Classification," Computer Graphics (SIGGRAPH '87 Proceedings) 21(4), July 1987, p. 55-64. Also in Tutorial: Computer Graphics: Image Synthesis, Computer Society Press, Washington, 1988, pp. 196-205. Predates SPD, uses recursive tetrahedron.
  • Subramanian, K.R., "Fast Ray Tracing Using K-D Trees," Master's Thesis, Dept. of Computer Sciences, Univ. of Texas at Austin, Dec. 1987. Uses balls, tetra, tree.
  • Fussell, Donald and K.R. Subramanian "Fast Ray Tracing Using K-D Trees," Technical Report TR-88-07, Dept. of Computer Sciences, Univ. of Texas at Austin March 1988. Uses balls, tetra, tree.
  • Salmon, John and Jeffrey Goldsmith "A Hypercube Ray-Tracer," Proceedings of the Third Conference on Hypercube Computers and Applications , 1988. Uses balls and mountain.
  • Bouatouch, Kadi and Thierry Priol, "Parallel Space Tracing: An Experience on an iPSC Hypercube," ed. N. Magnenat-Thalmann and D. Thalmann, New Trends in Computer Graphics (Proceedings of CG International '88), Springer-Verlag, New York, 1988, p. 170-87. Uses balls.
  • Priol, Thierry and Kadi Bouatouch, "Experimenting with a Parallel Ray-Tracing Algorithm on a Hypercube Machine," Eurographics '88, Elsevier Science Publishers, Amsterdam, North-Holland, Sept. 1988, p. 243-59. Uses balls.
  • Devillers, Olivier, "The Macro-Regions: an Efficient Space Subdivision Structure for Ray Tracing," Eurographics '89, Elsevier Science Publishers, Amsterdam, North-Holland, Sept. 1989, p. 27-38, 541. (revised version of Technical Report 88-13, Laboratoire d'Informatique de l'Ecole Normale Superieure, Paris, France, Nov. 1988). Uses balls, tetra.
  • Priol, Thierry and Kadi Bouatouch, "Static Load Balancing for a Parallel Ray Tracing on a MIMD Hypercube," The Visual Computer, 5(1/2), March 1989, p. 109-19. Uses balls.
  • Green, Stuart A. and D.J. Paddon, "Exploiting Coherence for Multiprocessor Ray Tracing," IEEE Computer Graphics and Applications, 9(6), Nov. 1989, p. 12-26. Uses balls, mount, rings, tetra.
  • Green, Stuart A. and D.J. Paddon, "A Highly Flexible Multiprocessor Solution for Ray Tracing," The Visual Computer, 6(2), March 1990, p. 62-73. Uses balls, mount, rings, tetra.
  • Dauenhauer, David Elliot and Sudhanshu Kumar Semwal, "Approximate Ray Tracing," Proceedings of Graphics Interface '90, Canadian Information Processing Society, Toronto, Ontario, May 1990, p. 75-82. Uses balls, gears, tetra.
  • Badouel, Didier, Kadi Bouatouch, Thierry Priol, "Ray Tracing on Distributed Memory Parallel Computers: Strategies for Distributing Computations and Data," SIGGRAPH '90 Parallel Algorithms and Architecture for 3D Image Generation course notes, 1990. Uses mountain, rings, teapot, tetra.
  • Spackman, John, "Scene Decompositions for Accelerated Ray Tracing". Ph.D. Thesis, The University of Bath, UK, 1990. Available as Bath Computer Science Technical Report 90/33. Ray tracer code can be found at his site.
  • Green, Stuart A., Parallel Processing for Computer Graphics, MIT Press/Pitman Publishing, Cambridge, Mass./London, 1991. Uses balls, mount, rings, tetra.
  • Subramanian, K.R. and Donald S. Fussell, "Automatic Termination Criteria for Ray Tracing Hierarchies," Proceedings of Graphics Interface '91, Canadian Information Processing Society, Toronto, Ontario, June 1991, p. 93-100. Uses balls, tetra.
  • Spackman, John N., "The SMART Navigation of a Ray Through an Oct-tree," Computers and Graphics, vol. 15, no. 2, June 1991, p. 185-194. Code for the ray tracer is available.
  • Fournier, Alain and Pierre Poulin, "A Ray Tracing Accelerator Based on a Hierarchy of 1D Sorted Lists," Proceedings of Graphics Interface '93, Canadian Information Processing Society, Toronto, Ontario, May 1993, p. 53-61. Uses balls, gears, tetra, tree.
  • Simiakakis, George, and A. Day, "Five-dimensional Adaptive Subdivision for Ray Tracing," Computer Graphics Forum, 13(2), June 1994, p. 133-140. Uses balls, gears, mount, teapot, tetra, tree.
  • Matthew Quail, "Space-Time Ray-Tracing using Ray Classification," Thesis project for B.S. with Honours, Dept. of Computing, School of Maths, Physics, Computing and Electronics, Macquarie University. Uses mount.
  • Klimaszewski, Krzysztof and Thomas W. Sederberg, "Faster Ray Tracing Using Adaptive Grids," IEEE Computer Graphics and Applications 17(1), Jan/Feb 1997, p. 42-51. Uses balls.
  • Havran, Vlastimil, Tomas Kopal, Jiri Bittner, and Jiri Zara, "Fast robust BSP tree traversal algorithm for ray tracing," Journal of Graphics Tools, 2(4):15-24, 1997. Uses balls, gears, mount, and tetra.
  • Nakamaru, Koji and Yoshio Ohno, "Breadth-First Ray Tracing Utilizing Uniform Spatial Subdivision," IEEE Transactions on Visualization and Computer Graphics, 3(4), Oct-Dec 1997, p. 316-328.
  • Havran, Vlastimil, Jiri Bittner, and J. Zara, "Ray Tracing with Rope Trees," Proceedings of SCCG'98 Conference, pp. 130-139, April 1998. Uses 5 normal SPD.
  • Sanna, A., P. Montuschi and M. Rossi, "A Flexible Algorithm for Multiprocessor Ray Tracing,", The Computer Journal, 41(7), pp. 503-516, 1998. Uses spheres.
  • Müller, Gordon and Dieter W. Fellner, "Hybrid Scene Structuring with Application to Ray Tracing," Proceedings of International Conference on Visual Computing (ICVC'99), Goa, India, Feb. 1999, pp. 19-26. Uses balls, lattice, tree.
  • Havran, Vlastimil, and Jiri Bittner, "Rectilinear BSP Trees for Preferred Ray Sets," Proceedings of SCCG'99 conference, pp. 171-179, April/May 1999. Uses lattice, rings, tree.
  • Havran, Vlastimil and Filip Sixta "Comparison of Hierarchical Grids," Ray Tracing News, 12(1), June 25, 1999. Uses all SPD. Additional statistics are available at this site
  • Havran, Vlastimil, "A Summary of Octree Ray Traversal Algorithms," Ray Tracing News, 12(2), December 21, 1999. Uses all SPD. Additional statistics are available at this site
  • Havran, Vlastimil, Jan Prikryl, and Werner Purgathofer, "Statistical Comparison of Ray-Shooting Efficiency Schemes," Technical Report/TR-186-2-00-14, Technische Universität Wien, Institut für Computergraphik und Algorithmen, 4 July 2000. Uses all SPD.
  • Havran, Vlastimil, "Heuristic Ray Shooting Algorithms", Ph.D. Thesis, Czech Technical University, November 2000. Uses all SPD.
  • Koji Nakamaru and Yoshio Ohno. "Enhanced breadth-first ray tracing," Journal of Graphics Tools, 6(4):13-28, 2001. Uses all SPD. Renderings include up to a billion primitives.
  • Simiakakis, George, Th. Theoharis and A. M. Day, "Parallel Ray Tracing with 5D Adaptive Subdivision," WSCG 2001 Conference Proceedings, 2001. Uses 5 normal SPD plus teaport.
  • Havran, Vlastimil and Jiri Bittner: "On Improving KD-Trees for Ray Shooting", Proceedings of WSCG'2002 conference, pp. 209-217, February 2002. Also see Havran's page about Libor Dachs' ray tracing visualization system.


Eric Haines, On-Line Editor / [email protected]

Last change: July 6, 2011

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