Realistic material property for specular and roughness for real materials

Support Materials and Textures
1

Hi there

silly question but is there a database that tells you what values one should use for specular and roughness to generate materials like plastic paper steel etc ?

I know IOR for transparent materials but not for the reflection quality.

2

Hi,

This is a great video breaking down the PBR material. I was surprised to discover that the specular value of 0.5 is pretty good for a wide range of materials.
He explains all about specular in the first five or six minutes, as well as linking to a list of IOR values, and giving a formula for converting IOR values of dielectric materials to a 0-1 range to use with the specular input.

I found this video very helpful.

Regards,
Derek.

1 Like
3

@Hikmet has put together a free book containing all sorts of physically based values, it might have what you’re looking for: Physical Based Values List E-Book (2nd Edition)

3 Likes
4

thank you so much ! I forgot about the CG Master video and the PDF is a great handout for students !

2 Likes
5

took a bit of searching but found it again, had lost my bookmark :frowning:

2 Likes
6

yes I remember this one now - thank you !

watching this right now pretty amazingly well done

1 Like
7

Ah yes I did watch that but did not try it yet. Was not sure if I want to mess with the profiles (unless I confuse him now with someone else).

8

I’d say no. Specular is generally 0.5 for dielectrics (IOR 1.45’ish - it’s close enough), but could be less for porous versions of it even if listed at 1.45’ish. Looking at i.e. rubber in a microscope you can see a lot of “pores/holes” where specular energy would get lost instead of reflected. Sure you can convert accurate IOR values to specular, but it’ll be some theoretical perfection that often will disagree with what you see. Hence the term is called “artistic value”. There are coatings that can be applied that both reduces (anti reflective glasses) and increases (telescope mirror and some optical lenses) it’s natural IOR.

Roughness isn’t a specific material quality, but a surface finish quality. A stone can be rough or perfectly polished. As can a metal, a piece of wood, rubber, or pretty much anything. The full range is valid depending on polish quality, so you’re basically left with using PBR cheat sheets to set what kind of look you prefer.