Planetary rendering tips

This page contains some advice for those of you out there wanting to render some of the stuff at this site. The information is mostly independent of the software you may be using. I'm not an expert in something like Lightwave, 3DS etc. so asking me software-specific questions is probably of little use.

Rendering planets and satellites

All the maps at this site are in simple cylindrical projection with longitude 0 at the left/right edges. This is illustrated (4673 bytes)

The maps should be rendered by projecting them onto a sphere (or ellipsoid for oblate planets like Saturn where the polar radius is 10% less than the equatorial radius). This should be done using something which in POV-Ray is called "spherical projection" (may be similar in other software). Do not use "cylindrical projection" (even though the map is in "simple cylindrical projection") - it is intended for projecting stuff onto cylinders and will result in highly distorted renderings although you might not notice this if you have not seen actual photos of the planet/satellite in question.

When rendering a planet and one or more of its satellites it is important to keep in mind that every satellite in the solar system always has the same hemisphere facing the planet. This is illustrated below. Notice that as seen from the planet, longitude 0 on the satellite is always on the center of the satellite's "disk". Consequently, longitude 180 faces away from the planet.

satellite.gif (7166 bytes)

The diagram above does not apply to planets, no planet always has the same side facing the sun so when rendering them it does not matter which longitudes face the sun.

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