Amiga Format 55/af055sub.adf/Imagine_FAQ.lha/Imagine_FAQ_3

Text File | 1993-07-07 | 43KB | 998 lines

Imagine FAQ #3 - 7/5/1993


+======================================================================+
|                         Imagine Mailing List                         |
|                      FREQUENTLY ASKED QUESTIONS                      |
|----------------------------------------------------------------------|
|                             Compiled By                              |
|                           Michael B. Comet                           |
|                              Steve Mund                              |
|                            Mark Oldfield                             |
|                             Dave Wickard                             |
+======================================================================+

        This is the Frequently Asked Questions posting for the Imagine
Mailing list.  This posting is sent every so often to answer general
questions that users of the 3D rendering software, Imagine by Impulse
Inc. may have.  It is aimed toward all users, especially newcomers to
the program.

        If you find any errors or have answers to other frequently asked
questions that you would like to have included in this posting, please
send e-mail to: [e-mail] (FAQ List).

        - Mike C.

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

Last Update   : July 5, 1993 Monday
Issue Number  : 3
What's New    : New format!  Nice sections for easier searching!
                Number 9 in the Detail Editor section. (Sect 2)
                New (small) section on Essence attributes! (Sect 7)

------------------------------------------------------------------------

CONTENTS:
=========

    SECTION 1 - Support Products/Sites
         1] Imagine related: References/Help Books/Magzines/ftp sites.
         2] How do I reach Impulse?
         3] What is the Imagine Mailing List and how to get it?

    SECTION 2 - Modeling and Detail Editor
         1] How do I brushmap a ground plane?
         2] How do I make glass?
         3] The Slice command doesn't work or gives me errors.
         4] How can I make a room so that the walls don't have cracks?
         5] When I select a group of points in the DETAIL editor, all I
            can do is drag them...not ROTATE or SCALE interactively.
         6] List of common Index of Refractions
         7] How do you make mirrors?
         8] How do I make "metals" and what are some good gold
           attributes?
         9] Is there a quick way to add faces to my object without
            using the Slice command?

    SECTION 3 - Forms Editor
         1] After a Forms Editor object is loaded into the Detail Editor
            and manipulated, it won't reload into the Forms Editor.

    SECTION 4 - Cycle Editor
         1] I made this animation sequence in the Cycle editor, but when
            I set it up in the stage/action editors, the motion of the
            overall object isn't there!

    SECTION 5 - Animation, Stage Editor and Action Editor
         1] Even though I move an Object/Camera/Light to a new
            POSITION/ALIGNMENT/SIZE in the STAGE editor, Imagine seems
            to 'forget' what I did!
         2] How do I use the Grow Effect?
         3] How do I use the Tumble Effect?
         4] How do you get something to roll (at the right speed!) while
            following a path?
         5] When I move a Tracked Camera in the STAGE editor, it doesn't
            realign and draw the Perspective view correctly!
         6] When I increase the number of frames in an animation I find
            my scene gets mangled in the first frame.  Why?

    SECTION 6 - Rendering and the Project Editor
           1] Why do objects render fine in Scanline, but disappear in
            Trace?
         2] I have a problem with Filtered objects/fog and the Global
            Backdrop!
         3] My animation frames look fine, but when animated, they have
            the "crawly" effect.
         4] What situations, parameters, attribute values, etc. require
            the most trace rendering time?
          5] How do I get rid of the "Jaggies?"
         6] How can I figure out pixel aspect for a given resolution?
         7] When making a disco ball effect, will a SPHERICAL light set
            at 255 be bright enough to cause visible spots on the
            surfaces in a scene?
          8] How long should it take to do a full trace picture with
            perhaps one transparent glass on a Amiga 3000/25? Is 4.5 hrs
            too much?
         9] Is there any particular format that Imagine prefers?  Ham?
            32 Color?  EHB?  24 bit 1000 x 1000?

    SECTION 7 - Essence Settings
         1] Electrical Arc
         2] Veined Marble
         3] Rough marble/rock

    SECTION 8 - Miscellaneous
         1] What the heck is BTW, IMO and other weird abbreviations...
         2] Rendering and refresh times are MUCH too slow, even with an
            accelerator. Are there any Basic tricks or hints to help?
         3] How long will before my renderings aren't ugly anymore?

    CLOSING - Closing statements and Disclaimer

========================================================================
                   SECTION 1 - Support Products/Sites
========================================================================

1] Imagine related: References/Help Books/Magzines/ftp sites.

  REFERENCES AND HELP BOOKS:

    "Imagine 2.0 User Manual", Impulse Inc, 1992.
                   (Yes....read the manual!)

    "The Imagine Companion", David Duberman, Motion Blur Publishing,
         1991

    "Understanding Imagine 2.0", Steven Worley, Apex Software
         Publishing, 1992.

  MAGAZINES:

    These are some good graphics magazines, most of which focus on the
Amiga computer.  If anyone has some other suggestions please post them
to the FAQ list!

    "Computer Graphics World"
    P.O Box 122
    Tulsa, OK 74101-9845
    (800) 443 - 6632
    (918) 835 - 3161 ext. 400
    (918) 831 - 9497 (FAX)
        (A general computer graphics magazine focusing on the
    latest technology from PC's to SGI's)

    "Amiga World"
    P.O Box 595
    Mt Morris, IL 61054-7900
    (800) 827 - 0877
    (815) 734 - 1109
        (A general Amiga computer magazine, focusing on both
    hardware, software, utilities and graphics)

    "Amiga Video/Graphics Magazine"  (formerly AVID)
    365 Victor Street
    Suite "H"
    Salinas, CA 93907
    (408) 758 - 9386
    (408) 758 - 1744 (FAX)
        (A general Amiga computer magazine, focusing on both
    hardware, software, utilities and graphics)

    "Video Toaster User"
    21611 Stevens Creek Blvd.
    Cupertino, CA 95014
    (800) 322 - 2834
        (A magazine focusing specifically on NewTeks Video
    Toaster device.  Nothing related to Imagine, but some more neat
    pictures to look at!)

  FTP SITES:

    There is now a new ftp site set up for Imagine related items
including pictures, animations, tutorials, objects, and help files such
as previous postings from the list, and this FAQ at:

    wuarchive.wustl.edu
    in the  /pub/amiga/incoming/imagine  directory.

        Under this directory are the following sub-directories:
        art
        archive
        anims
        objects

------------------------------------------------------------------------

2] How do I reach Impulse?

    Impulse Inc.
    8416 Xerxes ave. North
    Brooklyn Park, Minnesota 55444
    USA

    [phone]
    [phone]
    FAX: [phone]

------------------------------------------------------------------------

3] What is the Imagine Mailing List and how to get it

    (From the Imagine Mailing List Sysop, Dave Wickard)

        The Imagine Mailing List is a wide variety of Amiga computer
artists sharing friendship and knowledge. The main thrust of the List is
the Imagine renderer. Subjects discussed though have varied widely.
There are discussions of Imagine and it's competitors, Imagine wish
lists for future versions, 3D rendering principles in general, single
frame recording techniques and many more.

        With first day users thru battled scarred veterans  :-)  there
is someone at your level of knowledge on the List. We are always glad to
see questions from every level of user. So often a simple and seemingly
embarrassingly easy question will lead to an interesting comment on a
related topic.

    New products, both hardware AND software, are discussed as to their
relationship with Imagine and Amiga 3D rendering.

    Names of Amiga luminaries dot the list, and often join in to lend
their insights without the usual "noise" of a USENET newsgroup.

    There are over 300 individual sites receiving the Imagine Mailing
List, and they include many networks, BBS systems, user groups, and
individual computer artists from literally around the globe.  We share
one thing.  Interest in each other's work with Imagine.

    YOU can get the Imagine Mailing List. All you need is access to
Internet mail. Simply mail to the following address:

         [e-mail]

and in your subject line, enter the word "subscribe".

    If you are reading this from a Commercial System, ask the
Amiga Coordinator to set up an Imagine Mailing List area that
everyone can read.

========================================================================
                  SECTION 2 - Modeling and Detail Editor
========================================================================

1] How do I brushmap a ground plane?

    The problem with brushmapping a ground plane is that the ground
itself is off 90 degrees in relation to its' axis for proper brush
placement.  (Add a primitive plane, a ground and compare them).  The
following will properly set a ground wrap:

         1) Add a ground object, select it, go into attributes, select a
            brush to use.
         2) You will now be in a requestor for the type of brushmap and
            placement etc...
         3) Select TRANSFORM AXIS
         4) Click on ALIGNMENT and set X = -90.  Leave Y and Z at 0
         5) Click on SIZE and leave X = +640.  Set Y = +2, Z = +400
         6) Click on POSITION and Leave X = -320, Y = -200. Set Z = +1
         7) Click on PERFORM.
         8) If you want the brushmap to repeat forever click REPEAT.
         9) Click OKAY.

        Your brushmap will now be placed correctly.  You can of course
resize it on the X/Z axis if you wish for scaling purposes.

        Basically step 4 re-rotated the brush axis properly and 5 and 6
fixed the size and position which Imagine screws up since it thinks it's
brushmapping on the other axis.

------------------------------------------------------------------------

2] How do I make glass?

        You can use the following Attribute setting for a default glass:

                   RED  GREEN  BLUE   VALUE
    COLOR          0    0      0      *
    REFLECT        0    0      0      *
    FILTER         255  255    255    *
    SPECULAR       255  255    255    *
    DITHERING      *    *      *      255
    HARDNESS       *    *      *      255
    ROUGHNESS      *    *      *      0
    SHININESS      *    *      *      0     (Very important see below!)

    PHONG = ON
    INDEX = 1.50
    FOG LENGTH = 0.00

    This should give you glass.

    One thing many people get confused by is:

         1) Shininess must be set to ZERO.  If you set this to anything
            but 0, the FILTER setting will not work.  This is just the
            way Imagine works since FILTER usage assumes shininess
            automatically.
         2) No background.  To get glass, you need surroundings.  If you
            render a glass cup on a pure black screen, you'll probably
            just see the highlights.  Adding global colors for Scanline
            and Ray Trace will give your object something to refract.
         3) Ray Trace.  To get refraction of surrounding objects
            exactly, you need to Trace, though scanline WILL approximate
            refractivity.

------------------------------------------------------------------------

3] The Slice command doesn't work or gives me errors.

    Due to the complexity of doing a 3D slice, sometimes Imagine gives
errors, or actually crashes during this operation.

    Things to do if you plan on using this function are:

         1) Save _ALL_ currently loaded object BEFORE trying to slice.
         2) If you get an error, move one of the objects slightly and
            try again.  Moving one of them may yield a working slice.

------------------------------------------------------------------------

4] I'm making a house which has many rooms and thus many walls, what is
    the best way of adding walls to the house so that they leave no
    cracks in the corners ?

        Three possible methods ---

        1. You can design your walls to be nice dimensions like 100
           or 1024 instead of 383.38. Place your axis at the corner
           of each wall. Then, to get seamless joints, use "snap to
           grid" in the project editor which will instantly adjust
           your walls to a perfect fit (If wall lengths are multiples
           of the grid line spacing).

        2. Create a 2D outline of the floorplan and extrude it up.
           Then simply pop a ceiling and floor on it.  The floorplan
           could be created either in Imagine or even a paint program
           and then auto-traced.  This means you will have to bust up
           a few polygons to add the windows and doors, but that is a
           minor task if you have a complex floorplan.

        3. A cheesy option is to make your walls too big. Then
          INTERSECT them. You get a mess BEHIND the wall, but if you
          don't look there, you'll never see it.


      wall 1           |
     ------------------+--
               \|/     |
      bug-eyed O.O     | wall 2
        monster v
                       |
                       |
      camera X

------------------------------------------------------------------------

5] When I select a group of points in the DETAIL editor, all I can do
   is drag them... it doesn't let me ROTATE or SCALE that clump of
   selected points.

        Imagine will let you move selected points, as well as rotate
and scale them. The limitation is that you cannot do this interactively
in Version 1.1 or earlier by using the mouse: The Transform command does
the manipulation. The picked points can be translated, scaled, rotated,
and positioned INDEPENDENTLY of the rest of the object. Rotations and
scalings all use the object's axis a reference point.  Absolute
positioning will move the FIRST point you pick to the location you
choose, and the rest of the picked points will be translated an equal
amount.  Interactive dragging is accomplished using the "drag points"
mode.

        Note: Versions 2.0 and later support interactive point editing.

------------------------------------------------------------------------

6] List of common Index of Refractions (and not so common too!)

         (All items except Vacuum are in alphabetical order)
         (STP = Standard Temperature and Pressure)

         MATERIAL                      Index
         -------------------------------------
         Vacuum ...................... 1.00000 (exactly)

         Air (STP).................... 1.00029
         Acetone ..................... 1.36
         Alcohol ..................... 1.329
         Amorphous Selenium .......... 2.92
         Calspar1 .................... 1.66
         Calspar2 .................... 1.486
         Carbon Disulfide ............ 1.63
         Chromium Oxide .............. 2.705
         Copper Oxide ................ 2.705
         Crown Glass ................. 1.52
         Crystal ..................... 2.00
         Diamond ..................... 2.417
         Emerald ..................... 1.57
         Ethyl Alcohol ............... 1.36
         Flourite .................... 1.434
         Fused Quartz ................ 1.46
         Heaviest Flint Glass ........ 1.89
         Heavy Flint Glass ........... 1.65
         Glass ....................... 1.5
         Ice ......................... 1.309
         Iodine Crystal .............. 3.34
         Lapis Lazuli ................ 1.61
         Light Flint Glass ........... 1.575
         Liquid Carbon Dioxide ....... 1.20
         Polystyrene ................. 1.55
         Quartz 1 .................... 1.644
         Quartz 2 .................... 1.553
         Ruby ........................ 1.77
         Sapphire .................... 1.77
         Sodium Chloride (Salt) 1 .... 1.544
         Sodium Chloride (Salt) 2 .... 1.644
         Sugar Solution (30%) ........ 1.38
         Sugar Solution (80%) ........ 1.49
         Topaz ....................... 1.61
         Water (20 C) ................ 1.333
         Zinc Crown Glass ............ 1.517

------------------------------------------------------------------------

7] How do you make mirrors?

        The trick with mirrors (or especially chrome-like objects) is
not setting the attributes of the mirror correctly, but making sure that
the environment is set up so something will be reflected into the
camera.

        If a mirror is TOO reflective, the mirror can actually become
invisible!  This is because the mirror's own flat glass/metal flat
coloring is overwhelmed by all the reflected light.  You see a PERFECT
reflected image, so the object itself isn't shown.  This is especially
true with flat mirrors.

        Some attributes that give a nice mirror polish:

                       RED  GREEN  BLUE   VALUE
        COLOR          150  150    150    *
        REFLECT        200  200    210    *     (a bit of a blue tint)
        FILTER         0    0      0      *
        SPECULAR       255  255    255    *
        DITHERING      *    *      *      255
        HARDNESS       *    *      *      255
        ROUGHNESS      *    *      *      0
        SHININESS      *    *      *      0

        PHONG = ON
        INDEX = 1.00
        FOG LENGTH = 0.00

------------------------------------------------------------------------

8] How do I make "metals" and what are some good gold attributes?

        One thing you can do to make your objects look more like metal
is to give them a specular setting close to the main color of the
object, but higher in intensity.  One mistake is to often make the
specular a pure white.  This makes objects look more like plastic than
metal.  For example, if you are trying to make gold, don't make the
specular pure white, but try a bright yellow or yellow/orange creame
color.

        Another problem is that many metals reflect the world.  For
example a chrome ball is pretty much just a shiny mirror.  Thus, if you
want to make realistic metals you will need to at least simulate
reflection. This can be done by adding a global reflect map, doing a
true ray trace or even just setting sky colors in the stage editor.


        You can use the following Attribute setting for a default gold:

                       RED  GREEN  BLUE   VALUE
        COLOR          205  205    80     *
        REFLECT        180  160    125    *
        FILTER         0    0      0      *
        SPECULAR       255  255    160    *
        DITHERING      *    *      *      255
        HARDNESS       *    *      *      255
        ROUGHNESS      *    *      *      0
        SHININESS      *    *      *      0

        PHONG = ON
        INDEX = 1.00
        FOG LENGTH = 0.00

        This should give you something close to gold.  Note that the
reflect values are fairly high.  You may wish to lower them to see how
it would look if you don't have anything to reflect etc...

------------------------------------------------------------------------

9] Is there a quick way to add faces to my object without using the
   Slice command?

        Here is a neat trick to add faces.  This method works best with
an object that is basially concave (such as a circle).

        1] Make the outline of your object, i.e.: points and edges.
        2] Extrude the object a distance away.
        3] Pick all the points that were just made...i.e.: The ones
           that now comprise the back face.  Using Bounding box
           selection would probably be helpful.
        4] Choose Join!
    5] Translate the now 1 pt back on the Y axis by the distance
           you extruded from, and position the point somewhere in the
           center of the object.

        The object is now a solid faced object with all faces connected
to one point on the center, just like the primitive disk object.

========================================================================
                       SECTION 3 - Forms Editor
========================================================================

1] I was working in the forms editor on an object, and loaded it
    into the detail editor for modification.  However, I can't seem
    to be able to get it back into the forms editor!  Help!

        Simply put, you cannot load objects saved from the detail editor
back into the forms editor.  The reason is the forms editor requires
a specified object structure which the detail does not.  Thus, saving
an object in the detail editor loses that information.

        When you work with the forms editor is recommended that you keep
a spare copy of the FORMS OBJECT saved separately from any detail
object. In this way you can then go back and make modifications in the
forms editor.

========================================================================
                       SECTION 4 - Cycle Editor
========================================================================

1] I made this really great animation sequence in the cycle editor,
    but when I set it up in the stage/action editors, the motion of
    the overall object isn't there!

        When using the cycle editor, Imagine only remembers changes in
size, position, and so on in relation to the main parent.  Thus, if you
make a change to the parent object, it gets forgotten.  What this means
is if you make a nifty robot jumping cycle, and make it in the cycle
editor so the robot actually move up etc... all that will be remembered
is the changes to the legs, arms and anything OFF of the PARENT.  The
overall rotations and movements to the main object will be gone.

        Two solutions exist.  One is to simply make those changes in
the stage editor each time you need to.  The second is to group a plain
axis before you start to your object.  (ie: Make the parent have a Null
link).  Then, you can rotate everything by rotating the main child
grouped right under this null axis.  This way you aren't moving the
"parent", and everything will be remembered.

========================================================================
          SECTION 5 - Animation, Stage Editor and Action Editor
========================================================================

1] Even though I move an Object/Camera/Light to a new
   POSITION/ALIGNMENT/SIZE in the STAGE editor, Imagine seems to
   'forget' what I did!

    All objects must have timelines split wherever there is a change in
position, alignment or size.  If you do not set this up, Imagine will
forget the changes no matter what.

    Rather than going back and forth to the ACTION editor and adding
timelines, you can have Imagine automatically create the timelines
properly so everything tweens as normal.  There are the "Position Bar",
"Alignment Bar" and "Size Bar" commands under the OBJECT menu in the
STAGE editor.

    So, if you have just gone to a frame and are making a new POSITION,
ALIGNMENT or SIZE for an object (or camera or light) to tween to, press
RIGHT AMIGA and 7/8/9 respectively.  Or use the respective bar commands
>from the OBJECT menu.  This will extend or put a 'split' in the timeline
for you (you can check this in the ACTION editor).  Also, don't forget
to "Save Changes"if you want to keep the motion!

------------------------------------------------------------------------

2] How do I use the Grow Effect?

        To use the grow effect, create an object in the DETAIL editor
that you wish to have 'extrude' over time.  Create a spline path as
normal in the detail editor.  This will be the path the object extrudes
along during the animation.

    GROUP (not join) the object with the PATH AS THE PARENT.  If you do
not make the path the parent, it will not work.  To do this, select the
path, then hold shift and select the object, then select group.  Save
your GROUP for loading in the animation.

    Finally, add the effect in the ACTION editor for the grouped object.

------------------------------------------------------------------------

3] How do I use the Tumble Effect?

    The tumble effect is used to tumble 1 or more objects during an
animation.  To tumble an object, create your object or objects in the
DETAIL editor.  Still in the detail editor add an axis.

        Group (not join) the AXIS to all the objects you want to tumble
with the AXIS AS THE PARENT.  Then load the GROUP into the STAGE/ACTION
editor and add the effect as normal.

    NOTE: The reason for the null object (axis) as parent is that
Imagine does not TUMBLE the PARENT, just the children.

------------------------------------------------------------------------

4] How do you get something to roll (at the right speed!) while
   following a path?

        Getting an object to spin (like a plane doing a barrel roll) is
easy- you align to path, then set Y rotation to be from 0 to 360 and it
will do a complete spin. This is not in the right direction for a
rolling ball, though. [Annoying feature- you can't say from 0 to 720 for
two spins, or 0 to 3600 for ten.] To get it to roll I created a second
path, which was basically a larger copy of the first, so the first path
was just inside of the second path. I had an axis (a track) follow this
new, outside path, then used "align to object" to make the sphere point
to the axis.

        Thus, as the ball moved along its path, one end (the positive Y
axis direction) was always pointed at right angles to the direction of
motion.  Is this clear? Now using the "initial Y angle" and "final Y
angle" I set them to 0 and 360 and it rotated as it rolled. As a special
effect, I raised the "track path" a little in the Z direction so the
sphere looks a little bit like a top rolling around, since the spin axis
was not horizontal anymore.

        An alternative would be to make a cycle object, rolling around
the X axis.  This is equally valid, but I did it this way first.

------------------------------------------------------------------------

5] When I move a tracked Camera in the STAGE editor, it doesn't realign
   and draw the Perspective view correctly!

    If you have Imagine 2.0 or higher, press RIGHT AMIGA and the K key
together, or select "Camera (Re)track" from the OBJECT menu.  This will
make the camera repoint to the track from the new position and will
redraw the perspective view.

        If you have an older version of Imagine (or if you just want to)
you can press RIGHT AMIGA and the C key or select "Goto" from the FRAME
menu.  Go to the current frame you are already on which will cause
imagine to redraw everything.

------------------------------------------------------------------------

6] I have found that after creating a scene in the Stage editor, and
    then deciding that I want an animation and adjusting the highest
    frame count, my scene gets mangled in the first frame.  Why?

        Well, it seems to me that this will happen if you don't split
your channel bar from the first frame (where you want stuff to be
exactly) to the second frame. I usually setup my scenes so that I have
the first frame all set as it should be and then I do my transformation
>from frames 2-whatever. In this way, the first frame is ALWAYS where
it's suppose to be no matter what changes I make in the remaining
animation.  If you look at your channel it should have a break between
frames 1 and 2 and then be continuous (if that's the way your animation
works out) from 2 on.

========================================================================
               SECTION 6 - Rendering and the Project Editor
========================================================================

1] Why do objects render fine in Scanline, but disappear in Trace?

    There are 2 possible causes for this.
         1) You are running out of RAM
         2) You objects are outside of the World Boundary

    To check #1 (for the Amiga), pull down The Project editor after you
start a render during the initialization phase.  Click once on the
Workbench backdrop and you should see how much RAM you have on the top
of the screen.  As Imagine starts to render, this will decrease.  If it
becomes close to 0, chances are, that's your problem.  To solve that,
buy more RAM.

    The other possibility is that the objects are outside of the world
boundary.  The world boundary is basically a box in which your objects
are placed.  When you enter the STAGE editor, you are placing objects in
this "virtual box" whose center is 0,0,0.

    When you Trace, Imagine clips ALL objects that fall outside of the
box.  The size of the world boundary is set in the ACTION editor.  In
this editor, there should be an item named GLOBALS.  Whatever numbers
are set in the SIZE timeline becomes the size of the box so that it lies
>from +/- Value for X,Y and Z.  The default is no information present,
which Imagine assumes is +/- 1024 units for all 3 coordinates.

        Thus to fix this problem you can:
         1) Scale your entire scene to fit inside the +/- 1024 size
            boundary
         2) Add a size line and set the X,Y,Z to the values you need
            (This can be found by using "coordinates" in the STAGE
            editor and moving the cursor around to find the values)
         3) Add a size line and set the X,Y,Z sizes to 0,0,0.  This will
            force Imagine to calculate the world size for ALL frames
            based on where objects are for the FIRST frame.  This is
            important since if your objects move farther out during
            subsequent frames, you will have to set the size manually
            (see 2 above) since it will now be outside the computed
            boundary, and thus clipped.

    Note: The world boundary has no effect in Scanline rendering.
    Note: Setting the World Size to 0,0,0 regardless of problems will
          usually DECREASE Trace times!

------------------------------------------------------------------------

2] I have a problem with Filtered objects and the Global Backdrop!

        For some reason, clear or glass like objects will not be clear
when used with a backdrop.  To get around this render with "genlock sky"
and then use an image processing program to composite the rendered image
onto the background pic for each frame.  Fog objects have a similar
problem.

------------------------------------------------------------------------

3] I have created an animation (Hurrah!) and when I look at each of
    the individual frames, they look just as I thought they might.
    However, when I animate them, anywhere I have applied the
    "roughness" parameter, surfaces look animated...with lots of
    "crawling" effect on them. What gives?

        Roughness should NOT be used on objects that will be animated.
(Unless of course, the "crawley" effect is what you're after). This is
caused by a bug in the roughness algorithm. One of the main work-arounds
suggested, is by using a very small or fine bump-map. Another work-
around is to create a DPaint (or for that matter ANY IFF) multi-gray
shaded screen and apply it as an altitude map.

------------------------------------------------------------------------

4] What situations, parameters, attribute values, etc. require the most
    trace rendering time?

        The list is long: reflections and refractions increase rendering
time significantly, anti-aliasing (0 longest)-BTW this you must edit in
the .config file and resolve depth (also in .config file), number of
polygons, camera position (obliqueness), size of brush maps and even the
numerical entries of solid textures, resolution, display and render
modes etc etc.

        The big ones are refraction, edge level(antialiasing, reflection
(along with "depth") and #of polygons. Pretty well in that order too.
Remember that a higher refraction index is longer rendering time also.
And yes the scale of the object means a LOT. Imagine uses something
called an *Octree* to calculate the scene.  This is related to the world
size setting which is also discussed here in article number 1 above.
The difference can go from *hours* to minutes, so scale your scene by
the size you make your world.  You can select everything in the scene
(including camera and lights) and scale it interactively.

------------------------------------------------------------------------

5] How do I get rid of the "Jaggies?"

        The .config file for anti-aliasing defaults to 30. This is ok,
but not great. The best is 0 and final rendering should always be 0. So
you must edit this file every so often (before opening Im) or build a
front end on the work bench (requires programming knowledge, though).
BTW, the anti-aliasing is EDLE in .config file.

    {for those unfamiliar with the term jaggies - they refer to the
way lines drawn by computers tend to haved a jagged or stair stepped
appearance, instead of a smooth continuous line.  This is usually found
more in low resolution images.}

------------------------------------------------------------------------

6] How do I figure out the pixel aspect for a certain resolution
    display?  I am rendering a picture to be displayed on a macII
    at 1024x768.  Does anyone know the formula or is it device
    dependent?

        Pixel aspect ratio depends both on the aspect ratio of the
display device (your monitor) and the resolution that fits onto that
screen. Most monitors use a 4 x 3 aspect ratio so that to achieve square
1:1 pixels, the resolution must also be 4:3. 1024 x 768 will achieve
this as well as 640 x 480. The Amiga typically uses a non-square aspect
ratio of about 1.2:1 such as 320 x 200, 640 x 400, 768 x 480, etc. So
the pixel ratio can be found using...

  (horiz res. / horiz display size) : (vert res. / vert display size)
If your monitor has a 4:3 aspect, you should have 1:1 pixels.

------------------------------------------------------------------------

7] When making a disco ball effect, will a SPHERICAL light set at 255
    be bright enough to cause visible spots on the surfaces in a scene?

        No, I bet that a light of 255 won't work too well. So crank
it up to 2000!  Lights are not limited to 255 (It is logical that lights
can be as bright as they want).  Values above 500 or so are pretty
severe; they cast strong shadows, like a very sunny day. Above 3000 or
so and it looks like you're world is lit by nuclear weapons.

------------------------------------------------------------------------

8] I have a Amiga 3000/25.  How long should it take to do a full
    trace picture with perhaps one transparent (nearly) glass?
    Does 4.5 hours sound reasonable to you?  I am running the
    floating Point version of Imagine.

        The floating point version of Imagine uses inline floating point
code for maximum speed.  It does not use the libraries.  I suspect that
the non-FP version uses the libraries, just in case. You can probably
SPEED UP your trace time SIGNIFICANTLY by scaling up the whole scene in
the stage editor (see question 4 above!). A trace time of 4.5 hours on a
3000/25 definitely a "wee bit" on the high side for a scene as simple as
you describe.

------------------------------------------------------------------------

9] Is there any particular format that Imagine prefers?  Ham?
    32 Color?  EHB?  24 bit 1000 x 1000?

        The best is a 24-bit image, of course. Anything works, but the
color range of a 24-bit will beat the tar out of a 16 color any day.
Exceptions would be objects with a few discrete colors, like a red,
white, and blue flag. Then a 24-bit and a 4 color image are equal in
quality. Note that Imagine converts them all to 24-bit internally,
though- the memory goes down equally for a 100 by 100 4-color as it does
for a 100 by 100 24-bit.

========================================================================
                       SECTION 7 - Essence Settings
========================================================================

1] Electrical Arc

        Here's how to make an electrical arc between two rods, like
something out of Frankenstien's lab.

    1] Start with a plane with 255 R,G,B on Color and a light blue
       (or whatever color you want the arc to be) in Filter.
    2] Use Ringfract as follows:
         Set the Z axis to point out of the plane, (rotate 90 on X)
         Low Trans Start=30      Low Trans Width=5
         Hi Trans Start =40      Hi Trans Width =5
         Set the color to 0,0,0 for RGB.
         Leave other settings at defaults
       Place the axis of Ringfract in the middle of the bottom edge of
       the plane.
    3] Now use Swapcrf to swap the color and filter values. Do this by
       setting all parameters to 0, and then setting the following
       values to 1:
         Filt -> N Color = 1
         Refl -> N Refl  = 1
         Color -> N Filt = 1

        Now when rendered, there should be something similar to an
electrical arc (or maybe some sort of plasma).  To have the arc grow,
rotate the Ringfract axis on X up or down so that the plane and cylinder
do not intersect at 90 degrees.  If you animate this it looks like the
arc gets taller until the arc breaks (i.e. the plane no longer
intersects Ringfract's cylinder in a curve, but instead in two lines).

        Also setting the plane to bright will make it look correct
in dim scenes.

------------------------------------------------------------------------

2] Veined Marble

        The veinedmarble texture is used twice, once for large, widely
spaced veins.  The second use is for finer, closely spaced veins.

        For veined green marble set the object color to 40,80,40 for
Red Green and Blue respectively. The texture veins are a gray-green
color.

  Text#1   Text#2    Parameter        Text#1   Text#2    Parameter

  800.0    300.0    Initial Scale       4.0      5.0      Turbidity
    7.0      7.0    # of Scales         0.9      0.98     Color Level
    0.4      0.4    Scale Ratio       120.0    120.0      Color Red
    0.6      0.6    Amp Ratio         150.0    150.0      Color Green
    0.4      0.4    Time Ratio        120.0    120.0      Color Blue
    0.0      0.0    Time                0.0      0.0      Fade 0..1
    1.0      1.0    Sharpness           0.0      0.0
   20.0     10.0    Vein Spacing        0.0      0.0

        Rotate the second texture 45 degrees around the X and Y axes
with respect to the first texture.  You may want to rotate the first
texture as well.

------------------------------------------------------------------------

3] Rough marble/rock

        This uses 2 textures, one for a main color variation, and
the other for the bump/roughness.  This is very effective for creating
stone surfaces.  Try these settings on a primitive plane.

    Object Attribs   R   G   B    Value
        Color     = 136 118 128
        Specular  = 153 134 132
        Dithering =                255
        Phong = On
        All others at 0.

    Texture 1:  fractalcolor       Texture 2:  bump
        Parameter        Value        Parameter        Value

        Initial Scale       15        Initial Scale       5
        # of scales         5         # of scales         4
        Scale Ratio         0.4       Scale Ratio         0.5
        Amplitude Ratio     0.4       Amplitude Ratio     0.5
        Time Ratio          0.4       Alt. Adjust         3
        Time                0         Fade 0..1           0
        Base->1 Trans       0.3       Axis placement left at default
        1->2 Trans          0.6
        Color 1 End         1
        Color 1 Red         70
        Color 1 Green       60
        Color 1 Blue        60
        Color 2 Red         255
        Color 2 Green       240
        Color 2 Blue        240
        Fade 0..1           0
        Axis placement left at default

        When rendered an off gray stone will be created.  Great for
caverns, dungeons and so on.  Just slap it onto the walls or columns
to give it good-ol' natural look.

========================================================================
                        SECTION 8 - Miscellaneous
========================================================================

1] What the heck is BTW, IMO and other weird abbreviations...

    BTW is an abbreviation for "By The Way".
    IMO is an abbreviation for "In My Opinion"
    IMHO is an abbreviation for "In My Humble Opinion"
    IML is an abbreviation for "Imagine Mailing List"
    :) is a sideways smiley face
    :( is a sideways frowny face
    ;) is a winking-eye face  etc...

------------------------------------------------------------------------

2] My rendering times and even my refresh times in the editors are
   much MUCH too slow, even with an accelerator. Is there any
   basic tricks or hints that are often overlooked that might help
   me out?"

        Always be sure to MERGE your objects. This eliminates multiple
faces, points and lines. Some objects have a VERY large number of these
and it can slow your times down by up to 1/2!

------------------------------------------------------------------------

3] When does one get good enough so that they don't render ugly
    pictures!

        Practice with a simple objects (to cut down trace time) over and
over and over.  Varying lighting & color etc.  This will allow you to
get the effect you want which is only a technical problem.

========================================================================
                CLOSING -  Closing statements and Disclaimer
========================================================================

        Hopefully this document is useful to people out there.  Once
again, if there is anything you want added/changed/deleted, please
e-mail as listed at the top of the document.

    What follows is a small disclaimer so no one gets sued for
information that is accidentally incorrect or misleading.  (If you find
a mistake...please send e-mail so it can be fixed!).

      Disclaimer: There is no guarantee regarding any information
                  presented in this document.  The information may not
                  be correct, useful or helpful.  The reader accepts ALL
                  responsibility for actions pertaining to reading this
                  document, regardless of consequence.

========================================================================
END OF IML-FAQ


--
+======================================================================+
|  Michael B. Comet -   Software Engineer / Graphics Artist  - CWRU    |
|  [e-mail]  - "Silence those who oppose the freedom of speech" |
+======================================================================+