TITLE: Oceans on Mars
NAME: Paul Bourke
COUNTRY: Australia
EMAIL: pbourke@swin.edu.au
WEBPAGE: http://www.swin.edu.au/astronomy/pbourke/povray/marsplanet/
TOPIC: Sea
COPYRIGHT: I SUBMIT TO THE STANDARD RAYTRACING COMPETITION COPYRIGHT.
RENDERER USED: PovRay
TOOLS USED: Custom software developed locally
RENDER TIME: 5 minutes per frame
HARDWARE USED: Dec Alpha farm
IMAGE DESCRIPTION:
This rendering is based upon the real topology data
from the Mola (Mars Orbiter Laser Altimeter). The height
is exaggerated by a factor of 30, the "clouds" do exist
but are carbon dioxide rather than water vapour.
The tallest mountain to the left is Olympus Mons which
is about 3 times the height of Mount Everest. The
deep trench is where NASA recently found evidence of
liquid water, it is 5,000 km long and 100 km wide in 
places. This rendering is taken 10,000 km above the 
surface, this is close to the orbital radius of one of
the moons, phobos.
DESCRIPTION OF HOW THIS IMAGE WAS CREATED:
The planet is rendered in PovRay as part of an animation
sequence. In that animation the "ocean" is slowly flooded
up to 200f the maximum mountain height and the atmosphere
is slowly introduced. The animation also includes a low
level approach. The most challenging aspect is the
huge amount of data used to represent the surface. The
dataset has a resolution of 1/8 degree, that is
   360 * 8 * 180 * 8 * 2 triangular faces
That is, over 8 million triangles! This was handled using
a number of strategies. back face culling was done for
the particular view point, faces below the ocean (a sphere)
were removed, level of detail further reduced the face
count on the smooth areas. The final renderings typically
involved just under 2 million faces.
The 90 second animation can be seen here
   http://www.swin.edu.au/astronomy/marsmovie/