Love this thread! Very informative, useful, and certainly helpful for 3D rendering.
Since however it’s labelled “The Science of CG”, I thought to toss some further examination everyone’s way. We need to keep in mind that photons do not yet “exist”, nor have ever been witnessed or observed. What we as examiners and scientists perceive is still quite literally a virtual event; a construct of mathematics to aid us in our understanding of physics.
An excellent essay on the topic:
A relevant excerpt:
EXAMINING THE CLAIMED EVIDENCE The challenge may seem incredulous but until someone can provide evidence, I will have to stand by it, lest I stand among the faithful believers. It amounts to this: no one, throughout the history of science has ever seen or detected a photon in space! To this day, there has never existed a single scientific evidential experiment that has shown the existence of a wave or a particle of light between emission and detection. So on what evidence do the believers rely on to justify their alleged photons?
Granted, not all renderers work using “photon GI” of course, and Maxwell and other unbiased renderers are based on Maxwell’s excellent mathematics. But we also tend to regard such scientists as near-gods, and tend to put “faith” in their math without any real reason to necessarily do so.
I’m excited to see progress in this field myself. Perhaps one day we’ll use a simpler, faster, more accurate mechanism to obtain our photorealistic results.