GeoSim is an add-on for generating photorealistic, customizable planets in Blender. It utilizes a dedicated shader nodegroup to produce physically-based volumetric atmospheres, providing direct control over attributes like atmospheric density, thickness, ambient light, and color via Mie scattering. The tool is compatible with both EEVEE and Cycles render engines.

The system includes support for image-based volumetric clouds that cast dynamic shadows on the atmosphere. It accommodates standard PBR workflows with full texture support for albedo, roughness, specular, normal, and emission maps. Additional capabilities include terrain displacement, indirect lighting, depth of field support, and a day/night emission mask to automatically disable city lights in daylight areas. The add-on also includes a set of Earth textures sourced from NASA, ranging from 2k to 16k resolution.