Here is my attempt at a photorealistic earth. I've tried this in the past with little success, but this time i think i am got it, hence the 'Reprise' in the title. Maya 7 - CS2 Photoshop. rendered in Mental Ray.
Ramp shaders create the atmospheric effects and the fresnel effect (note the gtreenish fringe round the edge). Layered shader containing a few different ramp shaders creting teh layering of overall density variation that appears most notable when the earth is scene from several angles. Specularity map merges with a ramp to control the cosine power based on the angle of incident with tHe Sun. Ambieent map shows city lights, and is controlled by a surface luminousity node to prevent it from showing at all on the dayside (this was causing problems initially).
Note on Stars: Be aware that when you are in space looking at the earth and take a picture, you cannot see any starts in that picture, because the Earth is about 1000 times bright then thoughs starrs. Kind of like trying to see starts in teh sky during the day. My goal here was to create an image that, if shuffled into a stack of NASA archive photo's, would blend in perfectly and no one would be the wiser, unless told.
Mostly a shading and Lighting experiement, as the geometry is painfully simple and many of the texturesare gotten from he ne. Some where altered or photomanipulated in CS2 (like adding that hurricane to the cloud layer, which was gotten from the NOAA website). Still was very fun to create. Feedback always welcome, as we never stop learning.