The Blue Marble is a famous photograph of the Earth taken on December 7, 1972, by the crew of the Apollo 17 spacecraft at a distance of about 45,000 kilometers (Wikipedia).
This would be one of the benchmarks against which I will compare my CG Earth. At this point, you may notice that the Earth looks very different in different photos and videos released by different sources. We shall investigate that in more detail at a later date.
If you have tried to create a CG Earth yourself, you'll probably know that the best freely available source of satellite imagery for texture mapping has been graciously provided by NASA since 2002, with the latest version being the Blue Marble Next Generation dataset released in 2005. With resolutions up to 500m/pixel, the dataset can be huge, with the entire Earth being 86400x43200 pixels. Even with enough computer memory, not every 3D software can handle that kind of image size.
With Maya, I had to chop the image up into little pieces around 8000x8000 each. Cutting the image up and saving them as individual images is tedious enough. Dividing the spherical UV projection into corresponding sections, each with correctly normalized UV coordinates, then assigning the correct surface material with the right image mapped is also a pain. To top it off, when the view is zoomed out and mipmapping kicks in, visible seams appear at the tile edges when you render.
As I plan to be able to render my CG Earth seamlessly at any level of zoom, this is clearly not an elegant solution. My choice was to either use a smaller texture resolution and hence not be able to zoom in close, or have several versions of the model for different levels of magnification.
As it turned out, the solution was to use a 3D software which is able to handle ridiculously large textures, and Maya was not on of them.
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