Several atmospheric radiative transfer models exist (see the overview of atmospheric radiative transfer codes). Planet uses the 6S model for several reasons:

• It integrates easily with the Planet platform.
• It is one of the more widely used radiative transfer codes.
• It was designed for satellite applications and corrects atmospheric interference, including on Landsat-8 imagery.
• Many scientific papers support its suitability for producing surface reflectance products.
• It is freely accessible and free from licensing restrictions.
• Its source code is available and straightforward to compile, which makes customization possible if needed.
• Configuration and output files are easier to manage with Py6S, a Python library.