These are my materials used in the scene. These 3 materials could be found in our hallway and stairway.

When I was observing black paint I found it looked smooth when I get far away from it and when I get closer it was not so smooth actually: there were many bumps. I took a photo as a reference and looked for a grunge map and noise map in Substance Designer which looked similar to these bump. Then I converted them into normal map.

Plastic and Wall are also very different subjects. Plastic is a translucency material so the border of scratches shows a little bit lighter, because border of scratches is thicker, therefore the light will pass through this place. But in realtime engine we can’t make plastic material into a SSS material casually, so I pick a lighter color into these place on my albedo (basecolor) map.

The wall in our houses is not so smooth even our eyes sometimes cannot capture the detail a little when we get far away from these objects, but our brain tells us there’s a little bump on the wall. It just like when you are looking into your keyboard you cannot find tiny noise on surface but your brain tells you they are not smooth enough.

So when we need to make fully realistic material we must observe these materials as close as possible and then we just need to simulate these tiny things.

Lighting the Scene