TITLE: Captain 8-Ball Conquers Mars
NAME: Matt Giwer
COUNTRY: USA
EMAIL: jull43@tampabay.rr.com
WEBPAGE: http://www.giwersworld.org/artiv/ & artii/ & artiii/         & artv/ 

TOPIC: Classic Science Fiction
COPYRIGHT: I SUBMIT TO THE STANDARD RAYTRACING COMPETITION COPYRIGHT.
MPGFILE: cap8ball.mpg
ZIPFILE: cap8ball.zip
RENDERER USED: 
    povray 3.5 and 3.6b2

TOOLS USED: 
    gimp, mpeg_encode, povtree, ImageMagick/montage,
         Jeffry J. Brickley's lightning include(mod'ed for 3.5)
RENDER TIME:        7473 frames @ 373x220 pixels

HARDWARE USED: 
    Celeron 400, 64M, linux 2.4.18-3 kernel
VIEWING:        mplayer and quicktime work, windows media player some
         versions have trouble, some will not work at all some just
         do not give the correct playing time.

GENERAL INFO:        http://www.giwersworld.org/artiv/mpeg.phtml has generic
         comments on size limited animations.

IMAGE DESCRIPTION:

        What a problem. Does it imitate the classic presentation with the
classic special effects with the wires visible? Or do it the way it should
have been done without wires? Why not both? 

        Speaking of the movies they have never been any respecter of correct
perspective. Even as recently as Babylon 5 in the matter of the jump gates,
the ships changed size as then entered or exited. They did not change in
size solely by distance. In the old movies a flying saucer could appear
larger than a building flying over it and then land in front of it much
smaller. The problems with Classic anything is to look like and cheat at the
same time.

        And if you remember Independence Day particularly the last combat
scene you may join me in concluding the 1930s Flash Gordon serials cared
much more about perspective and accurate portrayal of speed over distance.
By Hollywood standards, anything goes and that sort of negates the whole
point of rendering.

DESCRIPTION OF HOW THIS IMAGE WAS CREATED:

        This competition's new (for me) techniques. 

Matte/Green/Blue Screen:

        Using povtree on every frame is an exercise in patience. But if a
master is created on a blue screen background, background{Blue}, and
converted into a an image where the "blue" is transparent then it can be
used instead of calculating the povtree for every frame. A fifteen minute
frame reduces to 45 seconds. This is done by selecting blue on an image,
inverting the selection and copying it to a new image with a transparent
background. For more than this, read the fine docs for Gimp or Photoshop or
whatever.

        Similarly creating a decent random background of 100,000 stars can
take ten minutes per frame from loading and unloading memory and creating
bounding slabs in 64M RAM. Creating the image once and using it as a
image_map on a rectangular mesh hugely reduces the rendering time per frame.
Should you like the starfield style the files are in the .zip file.

        The nebulae (NASA images) uses the same technique. The selection
tool of the Gimp or Photoshop or whatever grabs all the black. Invert the
selection, copy and paste it into a new transparent background image. Save
with a format that preserves transparency such as TIFF. This layer is put
slightly closer to the camera than the stars.

        In general, techniques that are slow but tolerable for their
accuracy in stills quite often take much too long for animations. Maybe not
too long if you get it right the first time but who does? My worm started as
random creation of colored and sized spheres on a spherical surface and
about 90,000 frame level objects. I used the same technique to create an
targa image and then image mapped it to a sphere. Given the motion, nothing
was lost but ten minutes per frame.

Split Screen:

        Montage from ImageMagick was use to assemble separate renderings of
the landing rocket ship and what it sees looking at the ground. Each "half"
of the image is rendered at 186x220 and combined. The linux script is of the
form

#! /bin/bash
i=`expr 1000` 
upperlimit=`expr 1561`
while   $i -lt $upperlimit   
do

montage -geometry 186x220+0+0 left/al$i.ppm right/al$i.ppm -depth 8 -resize
373x220! lr$i.ppm

echo $i
i=$(($i + 1))
done

        This is included in the zip file.

        http://www.imagemagick.org/www/archives.html has linux and windows
executables. There are many other tools in the package. This is a swiss army
knife for graphics. Everyone should get it and consider the possibilities.

Shrinking:

        The approaches to Mars this repeats the trick I used in Escape and
Pursuit which I got from Babylon 5 of shrinking an object as it approaches
Mars (or jump gate) where the real perspective view would not work. When
moving close by the camera as from over the left shoulder into the distance,
we it to shrink by perspective by increase in z location you can't get more
than one large image close to the camera. By shrinking the object it can
mover small amounts in z and still appear become small with great distance.

        That still is not clear so here is how I first describe it.

        This trick is needed as when you see it in real life your visual
attention is on the small object which is like narrowing the angle of the
camera. But if you do that in the animation the entire image enlarges and
you lose the perspective of the entire frame. This is also used in UFOs over
cities. If it were to be the same change in distance per frame to actually
shrink to small size in the distance it could never appear large near the
camera.

UFOs Over Cities:  Hong Kong, Cincinnati, Tampa

        Back in the contest Journey a flying saucer flew over Washington DC
and landed at the south lawn of the White House. That went over well and one
comment suggested more of the same. So here is a twist on that with
overkill. I am betting someone will downgrade the work because it was used
too much this time. In any event this is how Hollywood still does it so
don't blame me if I pick up bad habits. At least one scene in Mars Attacks
appears to use exactly this method.

        The images start as plain Chamber of Commerce photos of city
skylines and work using both change in z and change in scale. In 8 Ball's
Journey it only changed in scale and the shadow was an object not a real
shadow. This time objects go behind buildings and clouds.

        Here a little Gimp or Photoshop familiarity is needed. A skyline
image is broken into two images with transparency. One is of the sky and the
other of the buildings. The sky image is place at a greater z distance and
scaled so that from the camera it appears to be the original image. The UFOs
start close to the sky image and move towards the camera while increasing in
scale. (I guess technically only the foreground needs to be transparent.)

        Getting them to exactly go behind buildings is trial and error. In
the Hong Kong scene part of the clouds on the left were included with the
buildings in the foreground so they could go through them.

        Then there is animating the water in the Hong Kong and Tampa stills.
See tampa.pov in the zip file for the method. It also contains the two
images to demonstrate the above technique. 

Misc.

        flame.inc for rocket exhaust and generic flame/teardrop lathe shape
is in the zip file.

        There is a Gimp for Windows which is as good as Photoshop and free
from www.gimp.org. It can save you the nuisance of pirating Photoshop.