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<H1>
Standard Procedural Databases
</H1>
by <A HREF="mailto:erich@acm.org">Eric Haines</A> et al.
<P>
<center>
<table>
<TR>
<TD>
<A HREF="balls.png"><img src="balls.gif" alt="balls" width=64 height=64></A>
</TD>
<TD>
<A HREF="gears.png"><img src="gears.gif" alt="gears" width=64 height=64></A>
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<TD>
<A HREF="mount.png"><img src="mount.gif" alt="mount" width=64 height=64></A>
</TD>
<TD>
<A HREF="rings.png"><img src="rings.gif" alt="rings" width=64 height=64></A>
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<TD>
<A HREF="teapot.png"><img src="teapot.gif" alt="teapot" width=64 height=64></A>
</TD>
<TD>
<A HREF="tetra.png"><img src="tetra.gif" alt="tetra" width=64 height=64></A>
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<TD>
<A HREF="tree.png"><img src="tree.gif" alt="tree" width=64 height=64></A>
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</table>
<I>click on an image to see a full size rendering<br>

(rendered with <a href="http://www.povray.org/">POV-Ray 3.1</a>)</I>
</center>
<P> You can <A HREF="spd3_14.zip">download the latest version of the SPD</A> 
  (currently 3.14), and also <a href="http://www.acm.org/tog/resources/SPD/spd.pdf">view
  the original IEEE CG&amp;A article</a> from Nov. 1987. This software package is not copyrighted and can be used freely 
  (for example, <A HREF="http://www.europa.com/~keithr/">WCT2POV</A>, 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 <A HREF="http://www.geocities.com/SiliconValley/Horizon/4977/macspd.html">Eduard 
  Schwan's SPD page</A>.
<P>For a newer set of more realistic environments for benchmarking ray tracers 
  (or renderers in general), see <a href="http://www.ce.chalmers.se/BART/">BART: 
  A Benchmark for Animated Ray Tracing</a>. 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.
<P>
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.
<P>
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.
<P>
The images for these databases and other information about them can be
found in <a href="http://www.acm.org/tog/resources/SPD/spd.pdf"><B>A Proposal for Standard Graphics Environments</B></a>, <I>IEEE Computer
Graphics and Applications</I>, vol. 7, no. 11, November 1987, pp. 3-5.  See
<I>IEEE CG&A</I>, 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.
<P> The <A HREF="NFF.TXT">Neutral File Format</a> (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. 
<P>
Other output formats are
supported:
<UL>
<LI>
        POV-Ray 1.0
<LI>
        POV-Ray 2.0 to 2.2
<LI>
        POV-Ray 3.1
<LI>
        Polyray 1.4 to 1.6
<LI>
        Vivid 2.0
<LI>
        QRT 1.5
<LI>
        Rayshade 4.0.6
<LI>
        RTrace 8.0.0
<LI>
        Art 2.3 (from Vort)
<LI>
        RenderMan RIB
<LI>
        AutoCAD DXF [object data only]
<LI>
        Wavefront OBJ format (polygons only)
<LI>
        RenderWare RWX script file
<LI>
        Apple 3DMF
<LI>
        VRML 1.0
<LI>
        VRML 2.0
</UL>
Alexander Enzmann receives most of the credit for creating the various
file format output routines, along with many others who contributed.
<P>
There are also reader programs for the various formats.  Currently the
following formats can be read and converted:
<UL>
<LI>
	NFF
<LI>
	DXF (just 3DFACEs)
<LI>
	OBJ
</UL>
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:
<UL>
<LI>
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).
<LI>
No real tessellation of polygons is done when needed for conversion,
all that happens are that polygon fans are created.
<LI>
You might find the images you obtain are mirror reversed with some formats
(e.g. VRML 2.0 files).
</UL>
<P>
The <A HREF="http://www.acm.org/tog/GraphicsGems/">Graphics
Gems V</A> code distribution has a simple z-buffer renderer by Raghu
Karinthi, using NFF as the input language.
<P>
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 <A HREF="http://ourworld.compuserve.com/homepages/bob_jenkins/blockcip.htm">Bob Jenkins</A>.
To show what a difference it makes, check out images of models made with the
<A HREF="old.jpg">original hash function</A> with a large size factor,
<A HREF="new.jpg">replacement hash function</A> I wrote (still no cigar),
and
<A HREF="jenkins.jpg">Jenkins' hash function</A>.
<P>
For more information on the SPD, see the README.txt file included in the
distribution.
<HR>
<H2>Compatibility Notes</H2>
<H3>Linux</H3>
<p>On some (all?) versions of gcc on Linux, the following correction to the code 
  is necessary:</p>
<p> libinf.c, line 33: </p>
<P>
FILE *gOutfile      = stdout;<BR>
change to<BR>
FILE *gOutfile      = NULL;
<P>
<HR>
<H2>Research Works using SPD</H2>
Timing comparisons for the various scenes using a wide variety of free software 
ray tracers are summarized in <I>The Ray Tracing News</I>, <A HREF="http://www.acm.org/tog/resources/RTNews/html/rtnv3n1.html#art10"><B>3</B>(1)</A> 
(many), <A HREF="http://www.acm.org/tog/resources/RTNews/html/rtnv6n2.html#art3"><B>6</B>(2)</A>, 
<A HREF="http://www.acm.org/tog/resources/RTNews/html/rtnv6n3.html#art5"><B>6</B>(3)</A>, 
<A HREF="http://www.acm.org/tog/resources/RTNews/html/rtnv8n3.html#art11"><B>8</B>(3)</A>, 
and <A HREF="http://www.acm.org/tog/resources/RTNews/html/rtnv10n3.html#art9"><B>10</B>(3)</A>. 
Here are some research works which have used the SPD to benchmark their ray tracers 
(please let <A HREF="mailto:erich@acm.org">me</A> know of others): 
<UL>
  <LI>Kay, Timothy L. and James T. Kajiya, "Ray Tracing Complex Scenes," <I>Computer 
    Graphics</I> (SIGGRAPH '86 Proceedings), <B>20</B>(4), Aug. 1986, p. 269-78. 
  <LI> Arvo, James and David Kirk, "Fast Ray Tracing by Ray Classification," <I>Computer 
    Graphics</I> (SIGGRAPH '87 Proceedings) <B>21</B>(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. 
  <LI> 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. 
  <LI> 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. 
  <LI> Salmon, John and Jeffrey Goldsmith "A Hypercube Ray-Tracer," <I>Proceedings 
    of the Third Conference on Hypercube Computers and Applications </I>, 1988. 
    Uses balls and mountain. 
  <LI> Bouatouch, Kadi and Thierry Priol, "Parallel Space Tracing: An Experience 
    on an iPSC Hypercube," ed. N. Magnenat-Thalmann and D. Thalmann, <I>New Trends 
    in Computer Graphics</I> (Proceedings of CG International '88), Springer-Verlag, 
    New York, 1988, p. 170-87. Uses balls. 
  <LI> Priol, Thierry and Kadi Bouatouch, "Experimenting with a Parallel Ray-Tracing 
    Algorithm on a Hypercube Machine," <I>Eurographics '88</I>, Elsevier Science 
    Publishers, Amsterdam, North-Holland, Sept. 1988, p. 243-59. Uses balls. 
  <LI> Devillers, Olivier, "The Macro-Regions: an Efficient Space Subdivision 
    Structure for Ray Tracing," <I>Eurographics '89</I>, 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. 
  <LI> Priol, Thierry and Kadi Bouatouch, "Static Load Balancing for a Parallel 
    Ray Tracing on a MIMD Hypercube," <I>The Visual Computer</I>, <B>5</B>(1/2), 
    March 1989, p. 109-19. Uses balls. 
  <LI> Green, Stuart A. and D.J. Paddon, "Exploiting Coherence for Multiprocessor 
    Ray Tracing," <I>IEEE Computer Graphics and Applications</I>, <B>9</B>(6), 
    Nov. 1989, p. 12-26. Uses balls, mount, rings, tetra. 
  <LI> Green, Stuart A. and D.J. Paddon, "A Highly Flexible Multiprocessor Solution 
    for Ray Tracing," <I>The Visual Computer</I>, <B>6</B>(2), March 1990, p. 
    62-73. Uses balls, mount, rings, tetra. 
  <LI> Dauenhauer, David Elliot and Sudhanshu Kumar Semwal, "Approximate Ray Tracing," 
    <I>Proceedings of Graphics Interface '90</I>, Canadian Information Processing 
    Society, Toronto, Ontario, May 1990, p. 75-82. Uses balls, gears, tetra. 
  <LI> Badouel, Didier, Kadi Bouatouch, Thierry Priol, "Ray Tracing on Distributed 
    Memory Parallel Computers: Strategies for Distributing Computations and Data," 
    <I>SIGGRAPH '90 Parallel Algorithms and Architecture for 3D Image Generation 
    course notes</I>, 1990. Uses mountain, rings, teapot, tetra.
  <LI> 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 <a href="http://www.johnspackman.ukf.net/raytrace/index.htm">his
    site</a>.
  <LI> Green, Stuart A., <I>Parallel Processing for Computer Graphics</I>, MIT 
    Press/Pitman Publishing, Cambridge, Mass./London, 1991. Uses balls, mount, 
    rings, tetra. 
  <LI> Subramanian, K.R. and Donald S. Fussell, "Automatic Termination Criteria 
    for Ray Tracing Hierarchies," <I>Proceedings of Graphics Interface '91</I>, 
    Canadian Information Processing Society, Toronto, Ontario, June 1991, p. 93-100. 
    Uses balls, tetra.
  <LI> Spackman, John N., "The SMART Navigation of a Ray Through an Oct-tree,"
    <I>Computers and Graphics</I>, vol. 15, no. 2, June 1991, p. 185-194. <a href="http://www.johnspackman.ukf.net">Code for
    the ray tracer</a> is available.
  <LI> Fournier, Alain and Pierre Poulin, "A Ray Tracing Accelerator Based on 
    a Hierarchy of 1D Sorted Lists," <I>Proceedings of Graphics Interface '93</I>, 
    Canadian Information Processing Society, Toronto, Ontario, May 1993, p. 53-61. 
    Uses balls, gears, tetra, tree. 
  <LI> Simiakakis, George, and A. Day, "Five-dimensional Adaptive Subdivision 
    for Ray Tracing," <I>Computer Graphics Forum</I>, <B>13</B>(2), June 1994, 
    p. 133-140. Uses balls, gears, mount, teapot, tetra, tree. 
  <LI> Klimaszewski, Krzysztof and Thomas W. Sederberg, "Faster Ray Tracing Using 
    Adaptive Grids," <I>IEEE Computer Graphics and Applications</I> <B>17</B>(1), 
    Jan/Feb 1997, p. 42-51. Uses balls. 
  <LI>Havran, Vlastimil, Tomas Kopal, Jiri Bittner, and Jiri Zara, <a href="http://www.acm.org/jgt/papers/HavranKopalBittnerZara97/">"Fast 
    robust BSP tree traversal algorithm for ray tracing,"</a> <i>Journal of Graphics 
    Tools</i>, <b>2</b>(4):15-24, 1997. Uses balls, gears, mount, and tetra. 
  <LI> Nakamaru, Koji and Yoshio Ohno, "Breadth-First Ray Tracing Utilizing Uniform 
    Spatial Subdivision," <I>IEEE Transactions on Visualization and Computer Graphics</I>, 
    <B>3</B>(4), Oct-Dec 1997, p. 316-328. 
  <LI> M&uuml;ller, Gordon and Dieter W. Fellner, <a href="http://www.cg.cs.tu-bs.de/people/mueller/publications">"Hybrid 
    Scene Structuring with Application to Ray Tracing,"</a> <I>Proceedings of 
    International Conference on Visual Computing (ICVC'99),</I> Goa, India, Feb 
    1999, pp. 19-26. Uses balls, lattice, tree. 
  <LI> Havran, Vlastimil and Filip Sixta <a href="http://www.acm.org/tog/resources/RTNews/html/rtnv12n1.html#art3">"Comparison 
    of Hierarchical Grids,"</a> Ray Tracing News, <B>12</B>(1), June 25, 1999. 
    Uses all spd. <a href="havran_stats_grids.txt">Additional statistics are available 
    at this site</a> 
  <LI> Havran, Vlastimil, <a href="http://www.acm.org/tog/resources/RTNews/html/rtnv12n2.html#art4">"A 
    Summary of Octree Ray Traversal Algorithms,"</a> Ray Tracing News, <B>12</B>(2), 
    December 21, 1999. Uses all spd. <a href="havran_stats_octrees.txt">Additional 
    statistics are available at this site</a> 
  <LI>Havran, Vlastimil, <a href="http://www.mpi-sb.mpg.de/%7Ehavran/DISSVH/phdthesis.html">"Heuristic 
    Ray Shooting Algorithms"</a>, <i>Ph.D. Thesis</i>, Czech Technical University, 
    November 2000. Uses all spd. 
  <LI>Koji Nakamaru and Yoshio Ohno. <a href="http://www.acm.org/jgt/papers/NakamaruOhno01/">"Enhanced 
    breadth-first ray tracing,"</a> <i>Journal of Graphics Tools</i>, <b>6</b>(4):13-28, 
    2001. Uses all spd. Renderings include up to a billion primitives.<br>
  <LI>Havran, Vlastimil and Jiri Bittner: <a href="http://www.mpi-sb.mpg.de/~havran/ARTICLES/wscg2002.pdf">"On
    Improving KD-Trees for Ray Shooting"</a>, Proceedings of WSCG'2002
    conference, pp. 209-217, February 2002. Also see Havran's page about
    <a href="http://sgi.felk.cvut.cz/~havran/vis/visualization.html">Libor Dachs'</a>
    ray tracing visualization system. 
  
</UL>
<HR>
<H2>Graphics Benchmarks</H2>
<P>
Various graphics hardware comparisons are available online.
The <A HREF="http://www.specbench.org/gpc/">Graphics Performance
Characterization</A> group has been around for a long time.
<A HREF="http://www.gemtech.com/rwb/">Gemini Technology Corporation</A>
has begun an effort to benchmark graphics hardware accelerators and share
the results with the public.
<P>
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<ADDRESS>
<A HREF="http://www.acm.org/tog/editors/erich/">Eric Haines</A>,
On-Line Editor / <A HREF="mailto:erich@acm.org">erich@acm.org</A>
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<P>Last change: <I>February 2, 2005</I> 
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