https://thomasmansencal.substack.com/p/the-apparent-simplicity-of-rgb-rendering

 

The primary goal of physically-based rendering (PBR) is to create a simulation that accurately reproduces the imaging process of electro-magnetic spectrum radiation incident to an observer. This simulation should be indistinguishable from reality for a similar observer.

 

Because a camera is not sensitive to incident light the same way than a human observer, the images it captures are transformed to be colorimetric. A project might require infrared imaging simulation, a portion of the electro-magnetic spectrum that is invisible to us. Radically different observers might image the same scene but the act of observing does not change the intrinsic properties of the objects being imaged. Consequently, the physical modelling of the virtual scene should be independent of the observer.

www.plutorules.com/page-111-space-rocks.html

This help’s us understand the composition of components in/on solar system bodies.

Dips in the observed light spectrum, also known as, lines of absorption occur as gasses absorb energy from light at specific points along the light spectrum.

These dips or darkened zones (lines of absorption) leave a finger print which identify elements and compounds.

In this image the dark absorption bands appear as lines of emission which occur as the result of emitted not reflected (absorbed) light.

 

 

 

Lines of absorption