Subject: Comp.Graphics.Raytracing FAQ 2/2

From: [email-masked] (Jordan Kovacs)
Date: Sun, 29 Jan 1995 03:36:06 GMT

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3  Utilities and Other Software
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3.1 Modelling Software

    * MORAY

      MORAY, by Lutz and Kretzschmar [CIS: 100023, 2006], is a shareware
      modeller for PC's that directly supports POV-Ray 2.x primitives and
      more.  Registration is US $59 which will get you a protected mode 
      version, allowing full memory usage, plus all the usual support and
      upgrade info.

      The following, taken from the manual of the latest version, 1.5, 
      describes MORAY:
   
      1. What is MORAY?

         MORAY is a program with which you can design scenes for the POV-
         Ray raytracer to render. Contrary to normal scene design, with
         MORAY you design the scenes graphically. Up to now it was pretty
         difficult to imagine what the scene looked like, without laying it
         out on graph paper, or doing many test renders. MORAY is like a
         graph paper, it lets you place and change objects in wireframe
         while you see them. MORAY then generates the text file that POV
         needs to read.

         MORAY can thus also be used as a rapid prototype tool, to place
         objects quickly and write the scene file. You can then edit the
         scene file to suit your needs, just like you have been doing up to
         now.

         MORAY stores and works with POV-Ray primitives, as opposed to
         normal CAD systems, which mostly convert all objects to triangle
         meshes or similar polygon based formats when outputting. This
         ensures optimum performance and image quality from the raytracer.

         If you're a POV enthusiast and have access to CompuServe you
         should check out the GRAPHDEV forum for the latest news and tips
         on using POV. The RayTracing conference on PCGnet also carries
         lots of tips for POV.

         If you want to obtain the latest version of POV-Ray you can
         probably do so at the same source you obtained MORAY from.

      2. MORAY Features

         The emphasis in designing MORAY was to be able to work as
         intuitively and as graphically as possible. Most of the work can
         be done with the mouse.

         Three 2D views and a 3D view of your scene are visible on screen.
         You can perform all transformations of the objects in the 2D views
         with the mouse. The 3D view shows what the current camera will
         see, i.e. how POV will raytrace it.

         MORAY allows you to,

           -  scale, rotate and translate an object interactively on the
              screen.
           -  define cameras with which to view your scene, that will show
              the scene in wire frame as POV-Ray will raytrace it.
           -  graphically place a bounding box around an object.
           -  automatically create bounding boxes of any objects, including
              nested objects.
           -  make CSG or composite objects that can be nested arbitrarily
              deep.
           -  assign textures from the TEXTURES.INC file to your objects.
           -  define a new texture from within MORAY. You can then hand-tune
              this texture and MORAY won't interfere.
           -  place imagemaps graphically on objects, eliminating the
              tedious trial and error approach.
           -  manipulate the control points of a bezier patch to create
              shapes not easily created otherwise.
           -  create bezier patch meshes that consist of more than just one
              bezier patch primitive.
           -  create rotational, translational and tapering sweeps that are
              then output as smooth triangles.
           -  copy complex nested objects.
           -  create multiple copies of an object transforming each copy by
              amounts you specify in one easy step.
           -  specify the complexity of on screen objects.
           -  specify a region of the 3D view to render.
           -  integrate POV-Ray with MORAY, so that you can seemingly call
              POV-Ray from within MORAY.

      3. Requirements

         MORAY requires at least a 386, a VGA card and a mouse, although I
         cannot recommend this set-up. The minimum system, if you want to
         do some larger scenes, would be a 486DX/25 and 4MB memory, the
         shareware version needs 2MB EMS. EMS Memory is not required in the
         registered version, since it is a protected mode version.

         No specific software is required. You need to have POV-Ray 2.0 to
         raytrace the scene.

    * POVCAD
      
      (erm...)
 
    * PV3D

      (hmm...)

    * Blob Sculptor

      Blob Sculptor, v1.0, by Alfonso Hermida, Steve Anger and Truman Brown
      allows you to model shapes using blob primitives.   Output is to RAW, 
      DXF, BLB (internal format), POV, Polyray, Rayshade and CTDS.  In
      addition, the Windows version, ported by Ronal Praver, supports NFF,
      VideoScape and others.  NeXTStep and Open GL ports are expected soon.

3.2 Format Conversion Utilities

    Much of the following sections area taken from Amanda Osbourne's 
    <[email-masked]> "Raytrace Utilities for DOS (and Windows)" 
    list.  All are IBM PC based unless otherwise specified.

    Various utilities for converting from one file format to another:

    * 3DSPOV18.ZIP - Reads 3d studio mesh files. Writes out to Raw, Povray
          (1 & 2), Vivid and Polyray. (1993, Anger & Bowermaster)

    * DXF2POV.ZIP - DXF to Povray 1 conversion program. (1992, Collins, 
          Wells, Farmer & Gibeson)

    * DXF2RAW2.ZIP - DXF to Raw conversion program. (1992, Coy, Barber, 
          Daigle & Shiffman)

    * DXF2V22.ZIP - DXF to Vivid conversion program. (1992, Coy, Barber, 
          Daigle & Shiffman)

    * DXF3DS.ZIP - DXF to 3DS conversion program. (11, Yost/Autodesk)
 
    * OBJ2ASC2.ZIP - Wavefront object to 3d studio ascii converter. (1993, 
          Knight)

    * RAW2PV18.ZIP - Excellent utility that allows the user to adjust the 
          level of smoothing to apply to raw data as it is translated to 
          Povray (1 & 2.x), Polyray or Vivid 2. It can also add a camera and 
          light to the scene, making things fairly easy for the novice user. 
          (1993, Anger)

    * RAYL210.ZIP - Helpful utility to convert uLathe (an object creator 
          program for windows) files to RAW, Povray 1 & 2.x or Vivid 2 format. 
          (1993, Koehler)

    * TDDD2ASC.ZIP - TDDD (Imagine) to 3D studio ascii file converter.
          (1993, Knight)

    * TGA2GIF.ZIP - Converts targa files to gif files. (1991, Coy)

    * TGA2POV2.ZIP - Converts targa files to Povray 1.0 objects. (1992, 
          Steeves)

3.3 Creation Creators
  
    Utilities to aid in the creation of ray tacing objects:

    * BOXER1.ZIP - Object generator for Povray 1 (makes things like bathroom
          tiles and such based upon user input). (1993, Miller)

    * BRANCH1.ZIP - Tree creator for Povray 1. (1992, Weller)

    * CHAIN11.ZIP - Generates interlocking chain links for Povray 1.0. (1992,
          Koehler)

    * CM100.ZIP - CircleMaster utility for working with quadric spheres and
          ellipsoids; writes output to Povray 1.0. (1992, Brown)

    * COIL2.ZIP - Creates coiled objects for Povray 1.0. (1992, Kirby)

    * COIL2V.ZIP - Creates coiled objects for Vivid 2. (1992, Kirby & Cox)

    * CTDS230.ZIP - Connects a series of xyz dot coordinates. Though this 
          may not sound like much, this is an extremely helpful utility. 
          Supports Povray, Vivid and Polyray. (1993, Brown)

    * FORM.ZIP - All sorts of shapes can be generated with this program. 
          Form files consist of both shapes and commands (like twistx and 
          bend) and output may be Povray 1, 2 or .plg. Interesting program, 
          complementary to LPARSER.  (1993, Rowbottom)

    * FRGEN14.ZIP - Fractal Landscape (and other shapes too) Generator. 
          Though the program supports Vivid and Povray 1 & 2 directly, by 
          selecting raw output you can smooth triangles out with RAW2POV to 
          create nice hills and dales. (1993, Anger)

    * GEODOME1.ZIP - Utility for generating geodesic domes.  Output to 
          POV-Ray 2.x format as either facets or a mesh of pipes and joints.
          IBM PC executable, with source included.  This gets my vote, but 
          then it would...  (1994, Wardley)

    * LPARSER2.ZIP - L-system creator and mutator. This program is 
          particularly strong in the creation of organic looking forms. Many 
          data files are included with the program, which can be edited or 
          mutated to interesting effect. The language of l-systems is not 
          intuitive but the results can be truly stunning. The l-system file 
          that is read into the program can be outputted to DXF (both R12 and 
          3D faces), Povray 2.x, RAW and Renderstar VOL.  A couple of 
          accessory files are included with the main program and are strong
          programs in their own right. LVIEWER, is a wire-frame viewer that 
          reads .3DS, .RAW, Fractint .RAY, ARE-24 .POL and Lparser/ Renderstar 
          .VOL files. Rotation, zoom and pan the "camera" position, which
          can be saved to a file. This file can then be read into LV2POV. 
          (1993, Lapre)

    * LV20POVID - Newer and more powerful than LV2POV, this program reads an
          lviewer info file and generates data files in Povray (1 & 2.x) and 
          Vivid formats. The program's main strength lies in landscape 
          generation. (1993, van der Mark)

    * PLANT05.ZIP - Fractal plant generator. Outputs supported are Povray (1 
          & 2), Polyray and CTDS (Connect the dots smoother). (1993, Bryerton)

    * SUDS2.ZIP - Random positioning of lots of spheres (or other objects) 
          based on a variety of selections. (1994, Farmer, Wegner & Schwan)

    * TWISTER1.ZIP - Utility that will create spirals, coils, etc., of blobs,
          cubes or sphere.  IBM PC executable with source, output to POV 2.x
          format.  Another fine utility, but then I would say that... 
          (1994, Wardley)

3.4 Texture Editors

    * CMAP11.ZIP - Interactive color map creator for Povray. (1993, Lutz &
          Kretzschmar)

    * TCE20.ZIP - The color editor for Povray 1. (1991, Farmer)

    * TCEV20.ZIP - The color editor for Vivid. (1991, Farmer)

    * TEXMAKE2.ZIP - Early version of a utility to assist in texture creation 
          in Povray 2.x. (1993, Sigler)

3.5 Animation

    * AWKANI.ZIP - AWK script to output Povray animation data. (1992, Farmer)
 
    * DTA208.ZIP - Dave's Targa Animator (latest version 2.08) animates
          .tga frames into .fli's and .flc's. (199?, Mason)

    * PVQUAN16.ZIP - PVQUAN is a set of tools that allow you to create
          .fli creations on many platforms including UNIX and DOS.  Source
          code is provided and includes a hosts of useful functions like
          quantisation, .gif read, display, etc.

    * RAYSCENE.ZIP - Set of animation utilities, not raytracer specific.
          (1991, Jarik & Hassi)

    * RTAG21.ZIP - Ray Tracing Animation Generator (not raytracer specific). 
          A powerful program with its own language which supports, amongst 
          other things, spline path generation. (1993, Sherrod, $20 shareware)

    * SP03.ZIP - Spline paths for animations. Many output formats (Povray, 
          Vivid, Polyray, 3DV, Wire 3D) and acceleration and deceleration are 
          supported as well. (1992, Mason)

    * ZOOM11.ZIP - Interpolates steps between two positions for Povray 1.0.
          (1993, Brown)

3.6 Misc

   * DISP - an excellent viewing and post-processing utility for DOS.  
          Available as disp181a.zip on simtel mirrors.

   * FRACTINT - The ultimate fractals generator for the PC.  Invaluable for
          creating height fields, colour maps, viewing gifs or just creating
          fractals.  Latest version 18.2 available as frain182.zip from 
          wuarchive.  (1990-93, The Stone Soup Group)

   * NEOPAINT - A useful shareware paint package (registration US $45) for 
          creating images, height fields, etc., or just touching up finished 
          artwork.  Available from wuarchive.

   * NETPBM - A collection of utilities for UNIX (source distribution) and
          some other platforms that convert practically any format to any 
          other, amongst other things.  Available from wuarchive in 
          /graphics/graphics/packages/NetPBM.  (1991-1994 Poskanzer et al.)

   * PICLAB - An excellent package for converting and post-processing images.
          The version I have is 1.82 (1990 Crocker), but I'm sure there must
          be a more recent one.


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4  Further Information and Resources
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4.1 On-line Resources

    * Ray Tracing News

      Eric Haines <[email-masked]> has put together a phenomenal amount of
      information on ray tracing.  This he collaborates into his Ray Tracing
      News (RTNews).  They are a wealth of information and contain articles,
      sofware reviews and comparisons, book reviews and lists of everything 
      and anything to do with ray tracing.  They are available from many
      ftp sites, including:

      - princeton.edu          pub/Graphics/RTNews

      Also at Princeton in the /pub/Graphics/Papers directory, you can find
      Eric's ray tracing and radiosity bibliographies: "RayBib.*" and 
      "RadBib.*".  Eric has also put together an FTP list which he is 
      currently in the process of updating.  

    * Ray Tracing Bibliogaphy

      Rick Speer <[email-masked]> has also done a lot of work in bringing 
      together articles on ray tracing.  He maintains a cross-indexed ray
      tracing bibliography of over 500 articles from 1968 to the present.  
      These include papers from all Siggraph, Graphics Interface, Eurographics, 
      CG International and Ausgraph proceedings.  All citations are keyworded 
      and cross-indices are supplied by author and keyword.

      The bibliography is in the form of a 41 page postscript file which 
      is held at many ftp sites as "speer.raytrace.bib.ps.Z":

      - wuarchive.wustl.edu    graphics/graphics/bib/RT.BIB.Speer/
      - karazm.math.uh.edu     pub/Graphics/
      - nic.funet.fi           pub/sci/papers/graphics

      Ian Grimstead <[email-masked]> has also collected together
      a large collection of over 360 pages on-line of ray tracing papers.
      It is accessible via the World-Wide Web and has links to other on-line
      papers and documentation and to other ray tracing web pages.

      - hhtp://www.cm.cf.ac.uk/Ray.Tracing/

    * Ray Tracing Abstracts

      Tom Wilson <[email-masked]> has collected over 300 abstracts from
      ray tracing related papers and books.  The collections is available
      as plain ascii, with Latex and troff formatting programs included.
      It is available as "rtabs.*" from most the sites listed above.

    * Paper Bank Project

      Juhana Kouhia <[email-masked]> has collected together various 
      technical papers in electronic form.  Contact him for more information.

4.2 Other Newsgroups

    Some other newsgroups that may be of interest to you are listed below.
    Most of these have FAQs of their own which are available from
    rtfm.mit.edu [18.70.0.209] in the directory pub/usenet/news.answers

    - comp.graphics            
    - comp.graphics.algorithms 
    - comp.graphics.research
    - comp.graphics.visualization
    - alt.graphics.pixutils
    - alt.3d

4.3 Books

    Title:      Ray Tracing Creations 
    Authors:    Drew Wells and Chris Young
    Publisher:  The Waite Group
    Year:       1993
    ISBN:       1-878739-27-1
    US Price:   $39.95 (including disk)

    This book has been written by Drew Wells and Chris Young, two of the
    original developers of POV-Ray, as a user and reference manual for 
    POV-Ray.  Coming in at 573 pages, it's an excellent publication with 
    literally hundreds of stunning colour and monochrome pictures.  The only 
    drawback with the book is that it deals with POV-Ray version 1.0 which is 
    a little dated now that version 2.2 is out, but it is still a very 
    worthwhile investment for any POV-Ray user.

    Title:      Adventures in Ray Tracing
    Author:     Alfonso Hermida
    Publisher:  Que Corp. 
    Year:       1993
    ISBN:       1-56529-555-2
    US Price:   $27.95 (including disk)

    This book looks at Alexander Enzmann's ray tracer, Polyray (see section 
    1.2), and the author's own modelling system, POVCAD (see section 3.1) 
    which runs under Microsoft Windows.   The two work well together and the
    software is fairly well up to date.  The content of the book is good and,
    as in the previous book, there are many excellent illustrations and
    pictures.

    There are a few errors in the book, but Alfonso has produced an errata
    list which is available from:

    - wuarchive.wustl.edu    graphics/graphics/books/erratas/Adventures-In-*

    Title:      Photorealism and Ray Tracing in C
    Authors:    Christopher Watkins, Stephen Coy, Mark Finlay
    Publisher:  M&T Books
    Year:       1993
    ISBN:       ????
    US Price:   ???? (including disks)

    Provided with this book is source code for a ray tracer called Bob which
    is a subset of Stephen Coy's full-blown ray tracer, Vivid.

    Title:      Making Movies on Your PC
    Authors:    David K. Mason and Alexander Enzmann
    Publisher:  The Waite Group
    Year:       1993
    ISBN:       1-878739-41-7
    US Price:   $34.95 (including disks)

    Focusing on animation, this book is by David K. Mason, author of many 
    utilities including DTA - Dave's Targa Animator, and Alexander Enzmann,
    author of Polyray.  These tools, and others, are used to show how
    animations can be created on a PC.  It's a 210 page book that is laid 
    out well with ample illustrations.

    Title:      Object-Oriented Ray Tracing in C++  
    Author:     Nicholas Wilt
    Publisher:  John Wiley & Sons
    Year:       1993
    ISBN:       0471-304-158
    US Price:   $36.95

    This book takes the reader through many issues involved with the 
    development of a ray tracer in C++.  The last section of the book deals 
    with OORT, a class library for ray tracing.  It does not implement any
    input language or user interface but uses C++ calls to the library. 
    This is intuitive, due to the nature of C++, and extremely powerful
    as all the normal constructs of C/C++ such as loops, conditionals, etc.,
    are available.

    It's definately a programmer's book and some knowledge of graphics
    programming is assumed.  Because of this, the nature of the book is
    quite technical and can be hard going.  Eric Haines sums it up well:

    "If you want to make pretty pictures, get POV, Polyray, Rayshade, etc.  
    If you want to look at some nice C++ code for a vector & matrix library, 
    etc, check this code out."

    The code is available from:

    - wuarchive.wustl.edu    /graphic/graphics/ray
    - ftp.funet.fi           /pub/graphics/packages/ray-tracing/oort

4.4 Image Libraries

    A CD is available containing raytraced images, programs and utilities.

    Title:      L'ATELIER D'ATON  (2nd Edition - October 1993)
    Publisher:  D.P. Tool Club
                59657 Villeneuve d'Ascq
                B.P. 745
                France
    Contact:    Nicolas Kelemen - CompuServe 100012,1410

    Chris Morris <[email-masked]> is in the process of putting
    together another CD of images.  Contact him for more details.

4.5 Texture Libraries
     
    There is a library of building related textures (bricks, stone, etc.),
    for use as image maps at:

    - wuarchive.wustl.edu    /packages/architec/Textures 


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5   Frequently Asked Questions
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Now that you've been blasted with lists of FTP sites, utilitites, software, 
books, etc., etc., the only questions you could possibly have left to ask 
are those that...erm...aren't about FTP sites, utilities, software or books, 
I suppose.  So this section attempts to answer all the other questions that 
don't fit in above.  

At the moment, the list is fairly short, but then the group hasn't been going
that long.  As more questions get added, I'll no doubt re-organise and
categorise the questions better, but for now you'll have to take them as you
find them.

5.1 "Who is..."

    This section looks at some of the ray tracing artists and people who are 
    particularly well known for their work, be it images or software.  The 
    list is in strict alphabetical order as I don't fancy the task of trying 
    be subjective about who's pictures are better than who's.

    A VERY IMPORTANT POINT: A lot of these people have to pay for their Email 
    and 'net access.  DO NOT send them large images or other posts without 
    checking with them first.  Certain members of the POV team have recently
    had some pretty hideous costs (like $30 for 1 mail item) because of this.
    (Was that OK, Dan?)

    * Truman Brown 

      Truman Brown [Compuserve ID: 71477,221] is particularly well known for 
      his "woild" series of images.  He is a self-confessed "Obsessed 
      Programmer / trace-aholic" and has written a range of very useful 
      utilities, including Connect The Dots Smoother (CTDS), Circle
      Master (CM) and its companion, HYPE. 

      He has an understanding wife but his kids wish he didn't hog the PC so
      much.
   
      His utilities are available from most FTP sites and you can check out
      some of his images at:

      - uniwa.uwa.edu.au       /pub/povray/HALL_OF_FAME

    * Andrew Denton

      Andrew H Denton, or AHD, <[email-masked]> is a professional juggler
      and ray tracing artist.  He uses Lightwave on 2 040 Amigas and "lots of
      other toys".  Dragons feature heavily in his artwork and some of the
      pictures are truly stunning.  

      Images (no models) at:

      - icecube.acf-lab.alaska.edu    /pub/dragons/graphics/new/ahd

    * Dan Farmer

      One of the original POV-Ray development team, Dan [Compuserve: 70703,
      1632] or <[email-masked]> has created some 
      amazing images including the stunning "frosty.gif".  Dan explains
      how he did it:

     "The image was done in POV-Ray.  It's really quite simple.  The face
      is a freely available dataset produced by Mira Imaging... I'm sure it
      exists on the net somewhere.  The fractal shape is done with Fractint,
      using the 16 bit continuous potential features.  It's an inverted
      Mandelbrot set.  The silver texture is Silver1 in textures.inc.  The 
      sky is the usual bozo, but it's mapped onto a plane, not a sphere.  
      Floor is an imagemapped plane.  That's all there is to it!"

      You can get frosty.gif from:

      - uniwa.uwa.edu.au       /pub/povray/HALL_OF_FAME

      Unfortunately, Dan doesn't release his source code any more due to 
      certain unscrupulous sorts using his images for commercial purposes
      without payment or even permission.  Him keeping the source is his
      proof of ownership.  The Mira dataset for the face is now also available
      at uniwa.

      Dan is often around on the group and is very unselfish in spending time
      answering questions.  He has a quirky mailbox which goes AWOL if you 
      send him mail using elm.

    * Mike Miller

      If you ever need inspiration to see what can be done using POV-Ray,
      a piece of graph paper and a pencil, then look at some of Mike Miller's
      [Compuserve: 70353,100] images.  His pictures never fail to impress
      and he has undoubtedly produced some of the best pictures ever
      created with POV-Ray.  Mike created many of the demo scenes that come 
      with POV-Ray and he is responsible for the excellent textures in 
      "stones.inc".  

      The cover story of the January 1994 IEEE Computer Graphics and 
      Applications is entitled "Mike Miller's Many Hats" and looks at his
      work and includes many of his pictures.

      You can find his images and scene files on many sites.  A good one to
      start with is:

      - uniwa.uwa.edu.au       /pub/povray/HALL_OF_FAME
                               /pub/povray/images
                               /pub/povray/scenes

      Particular ones to look out for are MEAT (eyeballs mincing in a meat
      grinder), BENZ9 (model of a 1928 Mercedes Benz), DIVER1 & DIVER4 
      (pictures of deep sea divers with masks, SCUBA, etc), CAMERA, BUGS,
      SLUGS, FISH, etc., etc., the list goes on.

    * Andy Wardley

      Hmmm.  Modesty would normally prevent me from including myself in this
      section, but I've had so many requests and questions about "geodome" 
      that I'll use this chance to answer some of them.  

      Most questions have been about me releasing (or not, as the case may
      be) the scene files.  In particular, the sky texture has been in heavy 
      demand.  At the moment, however, I'm working on several other pictures
      that use this texture and variations on it.  When these are complete
      and I'm happy that I've had a good run of "exclusive use" of the sky,
      I'll probably open it up to the rest of the World.  I *can* tell you 
      that there's no trickery involved:-  it's just a normal, layered
      POV texture.

      The geodome was created using a utility I wrote specially for the
      occasion.  It's available as geodome1.zip from uniwa, with source
      included.  I'm curently working on Another utility, tentatively called 
      Poly<something> which will do geodomes and MORE!  It will actually 
      create, manipulate and tessellate all manner of polyhedra.  Expect it
      around the middle to end of June '94.

      The plasma is a turbulent marble texture, the green cloud is a bozo.
      Use of the filter keyword provided the transparency.  Finally, the
      floor is a height field.  I just took a <mumble> and then <mumble>
      <mumble> to create a blocky effect.  

5.2 "This picture doesn't trace."

    I know it might sound a bit obvious, but have you read the error message
    and tried to understand it?  Did you look in the manual?  Still nothing?
    I know I sound cynical, but it's not uncommon for people to have 
    something go wrong and then post straight to the 'net without even
    *trying* to figure out what went wrong.  A little patience and thought
    will solve the problem a lot quicker.

    Here's some common problems:

    * POV-Ray versions
  
      A lot of people get fooled when trying to trace old POV-Ray code
      with a new version.  Use the -MV1.0 option or use #version in the
      code to get the parser to treat it as old code.  You may find that
      you have to change any references to "shapes.inc" to "shapes.old".

      The POV-Ray docs can help you out here.  What do you mean "I haven't 
      got the docs"?  Go get them.  See section 1.1 for where to find them.

      Mike Miller's meat.zip seems to be one which crops up regularly. 
      Like most of Mike's work, meat.zip is POV-Ray version 1 syntax and 
      requires the aforementioned tweaking.  Without it, you'll get a big 
      white rectangle across the picture.  Mike also defines a "Silver"
      texture in fork.inc which conflicts with one in colors.inc.  You'll 
      have to change both references to it in fork.inc to something else, 
      like "MMSilver", for example.

    * Include files

      Have you checked that you've #included any include files that your 
      scene requires?  Include files tend to define colours, textures or
      objects that your scene may use.  Make sure you've told the ray tracer 
      where to look for include files.  For example, POV-Ray uses the -L 
      option to specify the directory where include files are.  E.g.

        -L/users/abw/povray/include

      The POV-Ray docs can help you out here.  What do you mean "I haven't 
      got the docs"?  Go get them.  See section 1.1 for where to find them.
      If you haven't actually got the include files, the same applies.

5.3 "I traced my picture, but I can't see anything."

    Have you actually put anything into the picture.  This isn't as silly as
    it sounds.  If you #declare on object (POV-Ray, again) like this:

        #declare my_object=
        union {
            sphere { <0, 0, 0> 1 }
            cylinder { <-2, 0, 0> <2, 0, 0> 0.5 }
        }

    Then you have just told the ray tracer that when you refer to "my_object",
    you actually mean a union of a sphere and a cylinder as shown.  To use
    the object, you must explicitly put it in:

        object { my_object }

    If the picture is completely dark, there are several things you can check:

    * Have you added any light sources?

    * Are the light sources blocked by anything?  (This is a favourite of 
      mine - I put in a large sphere for the sky and then add or move lights
      *outside* the sky sphere.  Where did the lights go?)
   
    * Where are you looking?  Are you sure your camera isn't inside an object?

    * Have you applied textures to your objects.  If you haven't, you might
      find that your ray tracer defaults your object to be black.

5.4 "Rotating this object doesn't work properly."

    With most ray tracers, rotating on object in a given direction rotates
    it around the axis *not* around its own centre.  If your object is 
    centred on the X axis and you rotate it in the X direction, it will 
    spin.  However, if it is some distance from the axis and you rotate it, it 
    will "orbit" the X axis, tracing a circle with a radius equal to the 
    distance of the object from the axis.

    Confused?  Think of the Earth spinning on it's axis.  It doesn't go 
    anywhere because it is centred on its axis (ignoring rotation around the
    Sun).  The moon, however is some distance from the Earth's axis and as
    it rotates around that axis, it travels through space, orbiting the Earth.

    To work out which way something will move, you need to know if your
    ray tracer uses a left or a right handed co-ordinate system.  POV-Ray,
    for example, uses a left handed system.  To work out which way an object
    will turn, point your thumb in the positive direction of the axis you're
    rotating in and the way you fingers curl indicate the direction of 
    positive rotation.  The hand you use to do this depends on your ray 
    tracer; left-handed, use left hand, right handed, use right.

    The same thing goes for scaling.  If your object is already some distance
    away from the origin, that distance will also get scaled.  For example,
    if you have a sphere 2 units away from the origin, with a radius of 1
    and you scale it by 2, the radius will now be 2 *and* the distance from
    the origin will be 4.

5.5 "Where can I find model data for..."

    avalon.chinalake.navy.mil is probably the best site you'll find for 3D
    model data.  See section 2.1 for more details.

5.6 "How can I view these pictures?"

    If you're using UNIX, the netpbm package is what you need.  It converts
    practically any format to any other and does a whole host of other things.
    To view the images, you can use XV which is available as a source
    distribution from many sites.

    If you're on a PC, it's a pretty good chance that you want to convert
    a .tga into a .gif, isn't it?  (You did use the +ft switch on POV-Ray
    to get a .tga didn't you?).  For this you can use PICLAB or tga2gif.zip.

    Details of where to find these packages can be found in section 3.

5.7 "Can I post binaries to this group?"

    In a word, NO.  The group is part of the comp.graphics hierarchy which
    should be, and is, strictly non-binary.  The reason for this is that
    uuencoded binaries tend to be very large.  By restricting binary postings 
    to the comp.binaries and alt.binaries hierachies, those sites who do
    not want to carry large volume groups can easily ignore anything under 
    these two streams.  

    Remember that most sites pay to transfer and store news and if they find
    that comp.graphics.raytracing is getting too expensive, they can just
    stop carrying it.  That is their right and priviledge.  Also remember
    that many individuals download this group via modems and pay for every
    byte.  They tend to get a bit annoyed when they have to fork out lots
    of money to download stuff they might not even want.  

    But what if you're really desperate to share with us your latest ray 
    tracing you've done depicting a mutant star camel exploding in a super 
    nova while naked dancers melt into a checkered floor? (the checkered floor
    always turns up sooner or later)  Great!  I'm sure we'd love to see it,
    but what you should do is post it to alt.binaries.pictures.misc.  You'll
    have to uuencode it and split it into small (<64k) parts.  Remember to
    put an informative title on it like:

      RAY TRACING: MUTANT.GIF: mutant star camel scene, part 1 of 6

    and include a text posting (part 0 of n) that describes the picture,
    states what format it's in (.gif, .jpg, etc.), what size it is, how
    many colours, and anything else you want to mention.  The more you put,
    the better.  
 
    You can then post this text message to comp.graphics.raytracing, along
    with a few lines saying "I've just posted this image to alt.binaries...
    ...pictures.misc".  BTW, ray tracing pictures generally get a good 
    response over in a.b.p.m and you'll often see request for them in 
    alt.binaries.pictures.d (the discussion group).

    If it's a utility you're posting, it should go to alt.binaries.misc
    instead of alt.binaries.pictures.misc, but the same process applies.

    The other alternative is to upload the picture or utility to an ftp site
    and use comp.graphics.raytracing to announce it in the same way.

5.8 "What does this mean..."

    Some ray tracing and related terms you might come across:

    * CSG (Constructive Solid Geometry) - A term describing ways in which 
          you can build up complex shapes from simple primitives by adding
          them together (union), taking one away from the other (difference)
          or getting the part where they intersect (intersection).

    * Height Field - An image that has extruded to be 3 dimensional. 
          Typically, the lighter areas will be high, and the darker areas
          lower.

5.9 "How can I Email someone on CompuServe?"

    Before you do, remember that they have to pay for every message you send.
    DO NOT send binaries or large files without checking first that it's OK.

    To mail to a CompuServe ID from the Internet, replace the comma with a
    period and stick "@compuserve.com" on the end.  For example:

        78654,321 become [email-masked]

5.10 "What is the difference between rendering and ray-tracing?"

    Ray tracing *is* rendering.  But then so is z-buffer rendering, scanline
    rendering, etc.  Ray tracing is just another algorithm used to render
    (i.e. "paint") pictures.

 
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6   Roll the Credits
-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-

Special thanks go to Eric Haines <[email-masked]> for his help and the wealth 
of information he has provided both directly and in Ray Tracing News, FTP 
lists, etc.

Thanks also to all those people who maintain other lists, bibliographies,
FTP sites, or have provided me with specific information, told me where to 
look, produced mini-faqs (thanks John) or have just posted answers to the 
group:

    John Beale <[email-masked]>
    Nick Fotis <[email-masked]>
    Jim Grimes <[email-masked]>
    Ian Grimstead <[email-masked]> 
    Laszlo Herczeg <las@[email-masked]>
    Chris W. Morris <[email-masked]
    Frank Neumann <[email-masked]>
    Bjorn-Kare Nilssen <[email-masked]>
    George Kyriazis <[email-masked]>
    Daniel Palermo <[email-masked]>
    Harry Rowe <[email-masked]>
    Heinz Schuller <[email-masked]>
    Rick Speer <[email-masked]>
    Greg Ward  <[email-masked]>
    Oliver Weyand <[email-masked]>
    Marius Watz <[email-masked]>

Finally, some king-size thanks to all those people out there who have 
developed, and continue to do so, all the ray tracing software and utilities
that keep us so occupied.  Wives, girlfriends and children may disagree on
this point, but thanks anyway.

Special awards in this category go to Dan Farmer [CompuServe: 70703,1632]
who wins the Award for "Not-Only-Doing-All-His-POV-Team-Stuff-But-Also-
Answering-Lots-of-Questions-And-Being-An-All-Round-Mr.-Nice-Guy", and
Chris Cason <[email-masked]> who gets the coveted "Also-
Does-His-POV-Bit-Especially-Being-Admin-of-the-POV-Site#2-And-Answering-
Questions-As-Well".

Sorry if I've forgotten anyone.  Thanks anyway.


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EPILOGUE
-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-

You may have noticed one or two gaps in the FAQ or spotted a glaring error,
or just thought of something that I really should have mentioned.  If that's
the case and you can provide some info or corrections, then let me know and 
sort it out.

Well here you are at the end of the document, and your trace is still only
half done.  You've probably got time to walk the dog before it's finished...

Happy Tracing.
--------
TO DO:

POVCAD review
PV3D review