I took a few measurements of things like my keyboard, mouse, and monitor with macbethcal, and I’ve unfortunately had to make quite a few guesses. In a render, it turns out pretty decent, but I still feel confused (and guilty that I am guessing) about how to properly measure specular materials.
Here’s an example of my keyboard and mouse:
The RGB value of the keyboard varies quite a bit depending on whether I sample a shiny part (reflecting the sun) or a non shiny part (reflecting the sky). Where should I be taking the sample? Is there a way to guess the specularity from the ratio of the shiny RGB to non-shiny RGB?