How to Add Dust to Any Model
You've likely heard artists harp on about how important "attention to detail" is. Why?
Because believability is half our job. We're trying to make an audience accept a computer generated image - which is harder than it would seems.
So to do that you need to give them every bit of help you can to sell it to them. That's why noticing small details from the real world, and integrating them in your render is such a vital skill, and the reason most cg job descriptions explicitly state you need it.
A few weeks ago I showed you how to create easy grunge, and this time we're making dust.
What is Dust?
Dust is made up of tiny particles of various different materials (soil, skin, hair, plants, you name it) that float around in the air and then settle on surfaces. Since these particles are so tiny, static cling lets them stick to any point on a surface, despite gravity constantly trying to pull it off.
This means that you'll always have a very fine layer of dust covering the whole surface of the object, as well as a slightly thicker coating sitting on the parts of the surface that face upwards (where gravity can't pull it off).