Views from above (random WIP shots)

These are intermediate work-in-progress images with some light post-processing done (dated 20 Oct 2011, first posted on Facebook): 

Above a Cloudless Sky
Most CG Earth renders have to reduce the amount of clouds or lower the density of the air (or omit the atmosphere altogether) so the Earth can look more recognizable to the average viewer.

Personally I like how the atmospheric scattering gives the Earth a soft translucent feel, though having little reference material to draw upon, I can only imagine how things actually look from further distances than the ISS and Space Shuttles have gone.

Clouds really ruin the look of the sky, especially from space. According to NASA, about 70% of the Earth is covered by clouds on an average day, which means we don't get to see much of the continents and ocean like we are used to seeing on maps and in atlases.

The atmosphere also tints the ground a shade of blue (due to atmospheric scattering) and sometimes occludes it altogether (an effect known as extinction, usually to describe the invisibility of stars from the night sky due to the Earth's atmosphere)

I'm still trying to figure out how to create nice volumetric clouds in CG...

Airglow and City Lights
One of the more interesting things I observe from ISS videos on YouTube was the "airglow" which was clearly visible as a thin yellow-green line at the top edge of the Earth's atmosphere for night exposures.

The colors of the "night side" of my CG Earth was set up to match the look of those videos. Since I'm using a linear workflow, this night shot had to be exposed correctly or else it's just a black image with faint yellow spots. This image was converted to 8-bit JPG from 32-bit EXR render:

A Thin Crust
The Hiimalayas are the tallest mountain ranges on the planet, about 6-8000m above sea level, yet they don't look as jagged from space as we might imagine. Many CG Earth renders has to exaggerate the elevation by an order of at least 3 times to get a decent effect. I kept to relatively realistic values so the mountains don't really stand out.

If the Earth is the size of an apple, the entire Earth's crust would be thinner than the apple skin, which means the highest mountains like Mt. Everest won't even pop out like a pimple ^^;;