This is a minimalistic renderer of the single scattering in the atmosphere of the Earth as described in http://nishitalab.org/user/nis/cdrom/sig93_nis.pdf:

Nishita, Tomoyuki / Sirai, Takao / Tadamura, Katsumi / Nakamae, Eihachiro
Display of the Earth Taking into Account Atmospheric Scattering
1993
SIGGRAPH

Usage

There is currently no command line parameter, simply enter the repository and run make; it will compile and render a $512 \times 512$ image (in .ppm format) of the atmosphere of the Earth. The Earth is centered in the image, its surface is considered totally black; sun light is considered directional and is coming from the upper right corner, a bit behind the Earth.

Dependencies

make and g++ with C++17 and OpenMP support for compilation, and a PPM capable image viewer. All this should be directly available in an Ubuntu distribution.