
            AutoVision 2.0
              11/25/94

    RENDER TERMINOLOGY
    ==================
    The following Render terms are used in this document:

    AutoCAD Render:
    Name of the ADS/RX rendering application supplied with AutoCAD
    Release 13

    R13 Render:
    Used interchangeably with AutoCAD Render

    autovis.arx:
    DOS AutoVision program executable

    render.arx:
    DOS AutoCAD Render program executable

    INCOMPATIBILITIES, LIMITATIONS, etc
    ===========================================================
    AutoVision Release 2 is NOT compatible with AutoCAD Release 12.


    - Fatal errors

       In the event of a fatal error AutoVision and Render attempt to
       shutdown.  Due to an AutoCAD limitation AutoVision and Render
       can't unload themselves and the user must (arxunload "autovis")
       or (arxunload "render").


    - Paper Space

       You cannot render models in Paper Space.  If you are in Paper
       space and attempt to invoke the RENDER command, the following
       message is displayed:

       ** Command not allowed in Paper space **

    - Color wheel

       With some display cards, there is a problem with the color
       wheel that appears in various lights and materials dialogues.
       The wheel inappropriately turns grey at times.  If this occurs, please 
       cancel the dialogue and re-enter. Also, if you use the slider or edit 
       boxes, you can ignore this problem. In any case, the numeric values 
       are correct.

    - Color Selector

       The Color Selector displays only the slider bars (not the Color
       Wheel) when R13 Render is configured for rendering to a separate
       display, configured for rendering to a full color display or
       configured for rendering to hardcopy.

    - 3D Studio and AutoVision

       If the texture of an imported file (using 3DSIN) does not render 
       properly, please reassign the mapping using the AutoVision mapping
       (SETUV) command.  3DSIN uses the same code as 3D Studio's 
       Surface/Mapping/Adjust/Acquire command to import the mapping 
       coordinates assigned in the 3DS file.  Since 3DS Release 1 did not 
       have this command, mapping information from files created in 3DS 
       R1 cannot be read by R13 Render.

       Another situation which may cause an imported 3D Studio file not to
       render properly is if some of the textures are solid materials 
       (.sxp).  AutoVision cannot render these materials.  To work around 
       this problem, assign R13 materials to the objects.

       Mesh properties - AutoCAD has no real way to store information at
       lower than the object level. For 3DS import, this means the object
       level and everything associated with faces (namely materials and
       smoothing) is discarded. Additionally, the edge visibility is also
       discarded (all are visible).
 
       3D Studio limits the number of verticies and faces per object
       to less than 65535.  Using AutoCAD's ACIS solid modeler to
       create objects it is easy to exceed 3D Studios limitation.  To
       get around this the user has several alternatives.  One is to
       split the solids into multiple pieces in AutoCAD then use the
       3DSOUT layer and ACI options to make sure 3DS objects are
       under 65535 faces when created.  The other option is to use
       FACETRES to lower the number of faces generated per object.
 
       All external application data is (XDATA and 3DStudio Appdata is
       discarded on both input and output.
 
       3D Studio Object attributes are discarded.

       3dsout does not support AutoVision landscape objects.

       3dsout does not support AutoVision animation.

       3dsin does not support 3D Studio animation.


    - DOS drivers for aniplay.exe

       The driver supervga.drv has been included in the "resource" directory
       which ships with aniplay.exe, in case the driver vesa.drv does not
       support your particular display.  It is recommended that you initially
       try to use vesa.drv for VGA and higher resolution display.  If your
       video display board does not respond to vesa.drv (that is, the driver
       name doesn't appear on the list of screen configurations in the Screen
       Format Menu, which you access by using the Screen Size command in the
       File menu), only then should you select supervga.drv as your screen
       size choice.


    - Landscape objects

       Landscape objects are implemented in a separate module called
       lsobj.arx which normally gets loaded when AutoCAD starts.
       In order for this to happen, there needs to be a file
       called acad.rx somewhere on your ACAD path that contains
       the line "lsobj.arx".  We have supplied an acad.rx file in
       the avis_sup directory which refers to our landscape
       object module.  If you already have an acad.rx file, then
       you MUST add lsobj.arx to it, and make sure that AutoCAD
       doesn't see the acad.rx in the avis_sup directory.

       If AutoVision finds that lsobj.arx has not been loaded when it
       starts, then it will load lsobj.arx itself.  However, if you
       open a .dwg or .dxf file which contains landscape objects before
       lsobj.arx has been loaded, they will not be recognized by
       AutoVision.

       For users who do not own AutoVision but would still like to
       render the AutoVision Landscape objects created with AutoVision
       lsobj.arx can be freely distributed.  The objects are rendered
       in their stand in form (ie shaded polygons).


    - Measure objects

       On new drawings if Measure in the acad.ini files is set to 1,
       the default in acad.dwg is 0 and acadiso.dwg is 1, the default
       Icon Scale (see Render/AutoVision manual for more information),
       is set to 25.4 instead of 1.0.


    - Save as R12...

       Attachments by aci will be lost on save as r12 since this was not
       a supported feature of R12.


    - Postscript output

       The postscript generated by Render and AutoVision's File output
       feature may not be readable by all postscript reader.


    - Fog bounds

       The near and far percent for fog is the percent distance between
       the near and far clipping plans NOT the camera and far clipping
       plane.  To adjust the clipping planes DVIEW must be used.
       (See the AutoCAD manual for details)


    - WMF and CLP files

       Support WMF and CLP files in the Render/MDI window has been dropped.

    - Render to Render Window

       When you use an 8-bit Windows driver and select 24-bit Color
       Depth in the MDI driver's Options dialog, the colors of images
       may look wrong.  This is a result of Windows making a
       "closest match" of the 24-bit colors to the rs in your 8-bit
       palette.  The full color information is still present, and if
       you cut and paste the image into a place with true 24-bit color,
       the image will appear correct.


    - Rendering to file 32 Bit TGA file

       Some software packages require a field in the TGA file header
       information to contain the number of bits of alpha present.
       32 bit TGA files created using the Render to File option do not
       fill in this information due to the hardware dependent aspect of 
       the TGA file definition.

       Most software that uses the alpha channel, including 3D Studio
       and Adobe Photoshop function perfectly with AutoVision Targa 
       files.  If you find that the AutoVision renderings to 32 bit 
       TGA files are not presenting alpha channel information setting
       the byte field at 11h in the TGA file to 08h may work.

    - Statistics

       When statistics is saved in a file, it records the date and time the 
       rendering was started. The time may not be correct. In that case, exit 
       AutoCAD and see if timezone is set on your system -- type set at the 
       DOS prompt and if you see a timezone entry (such as TZ=PST8PDT), reset 
       it by typing TZ=<return>. This should correct the problem.


    - Unable to load AutoVision

       If autoloading cannot find AutoVision check the following:
         -Check the ACAD environment variable or PREFERENCES dialog
          for the correct AutoVision directory.
         -Check to see if SHARE.EXE is running.  In this case, set
          autovis.arx and autovis.xmx to read only.


    - Canceling certain Animation commands

        A few of the Animation functions, especially the Walkthrough
        and the Preview commands prompt the user to enter a single
        keyboard character.  Due to limitations in AutoCAD's ability to
        deal with the Cancel character (control-C or ESC, depending on
        your platform) the Cancel character cannot be used as a substitute
        for the Quit character ("q").  If you inadvertantly cancel the
        Walkthrough or Preview command, you will be taken directly to the
        command-line level, and your previous camera view will not be
        restored.  None of the results of any previous Animation commands
        (except for the cancelled Walkthrough command) will have been lost
        as a result of canceling).



    DOCUMENTATION: errata
    ===========================================================

      Introduction, page 3, 5th bullet item on Subsampling, second sentence
      should read "This reduces image quality and reduces render time, 
      especially with complex models."

      Tutorial, top of page 14.  In windows, Ctrl-C doesn't terminate any 
      command for AutoVision or Render.  You must use ESC to terminate a
      command.

      The RPREF dialog box in User's Guide and Reference, page 153 is
      wrong -- Render dialog box is shown instead of Render Preferences
      dialog.

      The command (c:rpref....) should be (c:rmat....) in the Marble
      and Wood sections of the RMAT API Appendix. (p 244 & 248).

      SHOWMAT Command, p 265, 2nd example should read:

         (c:showmat (nentselp))

      AutoCAD Command Reference page 516, Map Files Path describes that it 
      sets the AVERDFILE variable and specifies the directory for map files.
      This should be AVEMAPS variable. (It also should read "directories")



    CONFIGURATION:
    ===========================================================

    - AutoCAD Color Configuration and AutoVision

       You cannot Render to viewports if AutoCAD is configured for less
       than 128 colors.


    - Large drawings and Windows swap files:

       Handling a large drawing that has many faces or a high resolution
       render to file/hardcopy/Render Window image might require
       a very large Windows swap file. Please consult your Windows
       manual about how to increase the Windows swap file size.


    - Install

       The AutoVision for Windows installation program creates a directory
       called ADSETUP on your hard disk. This directory contains two files,
       avsetup.exe and avsetup.inf.  Please delete the files and the
       directory from your hard disk.

    - avemaps.pth

       The file avemaps.pth acts as an extension to the AVEMAPS environment
       variable.  This file contains names of directories, one per line, that
       will be searched for image files.  It must be located on your ACAD path.
       This allows you to avoid problems with length limitations of environment
       variables on some platforms.
 
    - Menus
       On Windows the AutoVision menu is loaded from the acad.mnl file, so if
       you alter or replace this file, you may lose your AutoVision menu.  You
       can add the Lisp code from the bottom of the standard acad.mnl file
       to your customized version to reinstate menu loading.


    - Reconfiguration

       To reconfigure your render devices, select the "Reconfigure" option
       on the Rendering Preferences dialogue box or enter RCONFIG at the
       Command prompt. Select your rendering display device, and if you 
       want, select a rendering hardcopy device. If you change your mind
       about a device you have just selected, you cannot reconfigure a
       second time at this stage.

       You must exit the configuration menu and repeat the process. Select
       "Reconfigure" or enter RCONFIG, and configure the rendering display 
       and or rendering hardcopy devices again.


    - Hard copy configuration
 
      Do not cancel during initial hard copy configuration.  If you make a
      mistake, proceed to complete the configuration and then reconfigure.




     HINTS and TIPS for using AutoVision
    =====================================================================


    - Creating Shadows
         
       There are several trade-offs in deciding what method to use to 
       compute shadows with AutoVision.  There are 3 ways to create 
       shadows:
 
       -Shadow Volumes:  This technique computes additional polygons 
        which represent the shadows cast onto other objects in the scene.  
        This method has a high overhead in computation time and space 
        when there are a large number of polygon faces in the rendered 
        scene.  This method also gives the sharpest edges for shadows.
 
       -Ray Traced Shadows:  Raytracing will likely be a little slower 
        for simple scenes, but significantly faster than shadow volumes 
        for complex scenes.  The shadows are also sharp, but may 
        experience some aliasing, which can be improved by increasing the 
        anti-alias level of the rendering.  
 
       -Shadow Maps:  These are also the only shadows which can have soft
        edges, as controlled by the "Shadow Softness" slider.
 
        Shadow maps are stored on disk, and a map of size 'n' requires
        8*n*n bytes, so a 4096 shadow map could require a maximum of 128MB
        of free disk space.  The message "Write Error" indicates that there 
        was insufficient disk space for the file.  Of course it is best 
        to use as small a map as possible, but be aware that too small a 
        map will produce jagged shadow edges.  It is also a good idea 
        to keep the spotlight beam as small as possible, yet still cover
        the targeted geometry, or to use the "Shadow Bounding Objects"
        option in the "Shadow Options" dialog.  Additionally, point lights
        create 6 shadow maps each, so they can consume a very large amount
        or resources.


    - Customizing Your City List

       It is possible to customize the list of cities which appear on the 
       Geographic Location dialog.  The file sitename.txt, which is located
       in <directory where sitename.txt appears> is a text file which
       contains an alphabetized list of cities in the following format:
        
       Column      Meaning
        
          1        Sign of latitude, "+" if North, "-" if South
         2-7       Latitude in decimal degrees * 10000.  For example,
                     414975 means 41.4975 degrees.
          8        Blank
          9        Sign of longitude, "+" if West, "-" if East
        10-16      Longitude in decimal degrees * 10000.  For example,
                      1181447 means 118.1447 degrees.
         17        Blank
        18-End     Place name.  If the first character of the place
                     name is "+", this is a "major site" which is a
                     candidate place for the "Nearest city" search.
                     Otherwise the place simply appears in the list
                     of site names available for explicit selection.
        
       Note that the latitudes and longitudes in this database
       are given in *decimal degrees*.  If you're adding new
       locations from a source that gives degrees, minutes, and
       seconds, be sure to convert to decimal degrees!
        
       Example:
        
       +376183 +1223733 +San Francisco CA
        
       San Francisco will be treated as a big city located at
       37.6183 degrees N and 122.3733 degrees W.


 

    =====================================================================

            Autodesk Trademarks

    The following trademarks are registered in the U.S. Patent and
    Trademark Office by Autodesk, Inc.:  AutoCAD, Autodesk, Autodesk
    Animator,  AutoLISP, and AutoShade.

    The following are trademarks of Autodesk, Inc.:  ACAD, AME, Advanced
    Modeling Extension, 3D Studio, Autodesk Device Interface, AutoCAD
    Development System and AutoVision.


            Third-Party Trademarks

    All other brand and product names are trademarks or registered
    trademarks of their respective companies.

    JPEG support in AutoVision is based in part on work by the Joint
    Independent JPEG Group.
