TITLE: "Eruption!" or, "Is this a Landmark or what?"
NAME: Joost Egelie
COUNTRY: Belgium
EMAIL: joost.egelie@skynet.be
WEBPAGE: http://www.skynet.be/users/egelie/ but it still needsupdating...

TOPIC: Landmarks
COPYRIGHT: I SUBMIT TO THE STANDARD RAYTRACING COMPETITION COPYRIGHT.
JPGFILE: eruption.jpg
ZIPFILE: eruption.zip
RENDERER USED: 
    POV-Ray PPC 3.1g/b1/AUG99 Unofficial, by The Smellenbergh Team
               (if I had used the official Mac version by Eduard Schwan, the
rendering
                time would estimated to be 6 days, 19hrs and 56min!!!)

TOOLS USED: 
    Adobe Photoshop 5.0 for creation of height fields and the two
RAWs
               MacMingle (creation of my own) to combine the two RAWs into a DF3
file

RENDER TIME: 
    12hrs 15min 30sec

HARDWARE USED: 
    Apple Macintosh Performa 6200/64MB (Motorola PPC603e 75MHz
processor)


IMAGE DESCRIPTION: 

People turn their heads towards the sky as they witness the earth spewing out
hot showers of molten soil - for miles away in the vast surrounding area one
can see the sky turned into solid fire... is this a Landmark or what?


DESCRIPTION OF HOW THIS IMAGE WAS CREATED: 

This all started out as a fairly innocent experiment on height fields. Could I
place two height fields into each other to make a mountian with lava on it? It
turned out so. Then I plunged into the techniques of media, in order to make a
cloud of steam rising up from the volcano. But what ever way I crafted these
interiors and densities... no satisfactory plume of smoke came out. My last
resort would be a density-file; but I had no utilities to make such a file.
Until on night - I had a dream (merely overnight wonderings): what would happen
if I just took a picture, made it 3D by projecting it along its z-axis, and
"mingled" it with another picture treated the same way?... I wrote a simple
ANSI-C program that could do the job. And yes, the results were high above my
expectations. The volcano didn't just blow off steam - I made it erupt! (That's
why I love the Virtual Reality - one has the power of gods at his fingertips).
I added a customized Cloud-pigment in a sky_sphere, and put a very light normal
(ripples with turbulence) on the camera to emulate vision through hot air (but
I don't think it is quite visible with that inferno in the scene...).

More about the density-file (DF3):
POV 3.1 understands a new file format created by the POV-team to read in a file
containing a 3D cube with densities in it. However the POV-manual sais very
little about this technique, I managed to excavate its secrets. And it all
turned out to be easy matter - once you picture things in your head.
We start on two dimensions: the surface of an object. When I want to give it a
complex pigment (say, the world map on a sphere), I choose for an image_map.
That picture can be easily wrapped around the object in order to give it its
right appearance. In the same way I can use image data to make complex normal
bumps and dents.
Now picture a DF3 file to be an image_map subscribing the densities of gasses or
clouds *inside* an object. So in fact, this is a three-dimensional picture, or
what we all know from SciFi movies, a hologram.
What my utility did, was taking two pictures of 128x128 pixels, stretching them
out along the z-axis to make them both cubes of 128x128x128 pixels, and then
putting the first one into the flank of the other. The pixels were mingled in
this way:

            pix1 + pix2 
denspix =  -------------
                 2

It resulted into a DF3-file of 128x128x128 pixels (or bytes for all that
matters)
I still have to work on my utility, providing a better interface than the
command-line input it had shortly ago, mingling in different ways (such as
sqrt(pix1 x pix2) and so) and perhaps the possibility of mingling three or even
more pictures. But therefor I could need some help - it is very hard
programming on a Mac with only MPW.

Anyhow, I'll put out the basic and original ANSI-C source code on my website so
people can take a look at the process or even compile it for their own computer
platform.

Furtheron: Have FUN!!! (in three dimensions!)

Contact me at joost.egelie@skynet.be .
Contact the Smellenbergh team at smellenbergh@skynet.be .


