TITLE: The Waterwheel
NAME: Henry Bush
COUNTRY: UK
EMAIL: henry@unforgettable.com
WEBPAGE: http://www.soton.ac.uk/~hjsb196/
TOPIC: Old Technology
COPYRIGHT: I SUBMIT TO THE STANDARD RAYTRACING COMPETITION COPYRIGHT.
JPGFILE: wheel.jpg
ZIPFILE: wheel.zip
RENDERER USED: 
    POV-Ray 3.5 for Windows


TOOLS USED: 
    For the first time in ages I used nothing but povray. Unless
you count PSP to convert to PPM, Excel to effect motion blur, PSP to convert
PPM to JPG.


RENDER TIME: 
    Parse 1m 31s
         Render:  2d 9h 21m 42s (NB: time for one frame. See "motion blur",
below)


HARDWARE USED: 
    Athlon 650 running at 682MHz, 512Mb, Windows XP with 2Gb swapfile
(see "motion blur" below)
        

IMAGE DESCRIPTION: 


Water cascading over an over-shot waterwheel (slightly more efficient than the
standard under-shot), while the late day sun illuminates the spray.

A sincere thank you to JJ and Jenny, and to my father, Paul Bush, for their help
in the creation of this image. I couldn't have done it without you!


DESCRIPTION OF HOW THIS IMAGE WAS CREATED: 


Initially this was going to be an ancient waterwheel, ie, not used anymore. So
no cascades of water. But that would've been no fun.

The water is one big blob. Not true, the water in the entry pipe (the one
leading to the wheel) is a box, and that is CSG merged with the blob that is
the rest of the water. I wrote a macro to place 27,000 sphere elements in the
waterfall, along with 20,000 in the channel below. Note that the movement of
the water is not affected at all by the wheel (ie the droplets pass through the
fins). Not realistic, but it looks ok (I think).

Everything else is pretty straightforward I think. The media uses two density
patterns: both spherical (so it's greatest where the water hits the bottom,
fading out at the edges) and wrinkles (so it's not uniform).

Motion blur (not much, I admit, but it really adds to the image)

Short version: I simply rendered 5 frames and averaged them together.

Long version: I realised that rendering 5 frames on my machine would take me a
week over the deadline. So I enlisted the help of two people with c. 2GHz
Athlons, and it was done in a few days. Again, thank you very much to JJ, Jenny
and Paul for their help.
Then my problem was averaging. I could find no program to do a simple five-way
average. I tried the targa averager: it would do two no problem, but when I
tried to do more it failed. PSP can also do two, but no more. So I outputted
the files to PPM (ASCII format), and wrote an Excel macro (yes, I'm ashamed I
used VBA, but I couldn't be bothered to install Visual Studio!) to average
them. Et voila.

The main problem with this was the time-scale: I started designing with only two
weeks to go, and realised after about a week that it was going to take over a
week to render on my machine (render time was so long due to huge refractive
blob, as well as media). So it's all very rushed. Things I would've liked to
add:
        1. Froth on the water. I even had a plan for doing it, but time ran out
        2. Make a nicer brick-wall texture, or actually brick the wall
        3. Radiosity. Mmmm. But it would have tripled my render time.
        4. Photons. When a machine finally comes out that would let me render
this scene with photons in the time-scale I had, I will probably be able to
afford one (if I start saving now).