So, I spilled water on my grey shirt. And my shirt became a darker grey in that spot.
Why does this happen???
If water is clear and the albedo of my shirt is grey, why does it get darker?
Why is wet sand darker than dry sand? Wet asphalt darker than dry? etc etc etc??
Is this something to do with water refracting light on a rough material thus making it more rough? Materials like a plastic rubber ducky can get wet and not look darker, because it doesn't absorb water and it retains it's material properties. So how would you translate this effect on materials that do absorb water like cotton, or dirt to PBR? Does the albedo change? Does the material have more roughness/less reflection because of micro refraction or something? Whats the deal?!?