Physically Based Workflow Setup for Material Look Dev

[stevejjd]

Hello all,

I have a simple but incredibly important question for Chaos Group and also the forum members. The answer will help many who don't quite understand, which includes me.

I do not want to take for granted a material look dev scene supplied by another artist. I want to understand what exactly is going on in terms of creating a Physically Based Material Look Dev scene.

I believe the following attributes make a Physically Based Rendering Workflow.

1. Linear workflow
2. Area Lights, Dome Lights using HDRI
3. Materials - energy conserving
4. Calibration utilities including Grey and Chrome Spheres and a Macbeth Chart

I really want to know and understand how each attribute needs to be set up and why it needs to be that way.

a. Lights:
- How do I set up area lights and what are reference do we have to tell us exactly how bright a light is?
- How to benchmark a lights value? Can a light meter be used?
- Is there a simplified comparison chart for non technical artists to use which would be like... a light meter value of 'x' is about how bright an office room is....and so on? (for dummies)
- Are the light values of "Quality" HDRI an absolute? or are they to be adjusted?

b. Materials
- How do I know I have made a material that will hold up under different lightning conditions?
- How do I calibrate the specular of a material so its going to hold up ?

c. Calibration Utilites or references
- Exactly how do I use and set up the Grey and chrome Balls as well as how to use a Macbeth chart using Nuke?
- What is the non variable benchmark to which all the factors are calibrated?
- Is true PBR a myth, by which I mean, ultimately every factor must be adjusted to make the final look?
- In the end, is every CG shot adjusted till it just looks right?

d. Unification
- What are the steps to individually set up the elements?
- do all the elements need to be adjusted together with reference to each-other to make it just look good?



Please refer to this article to see what I mean by calibrating the elements that make a Physically Based Render. https://www.fxguide.com/featured/log...make-you-hurt/


Any feedback or tutorials on this will help me and possibly others a lot. Thanks again

Steve ~

[vlado]

I can only help you with a) and b) and somewhat c):

a) Most artificial light sources and manufacturers provide their luminous power in lumen, which you can directly enter into the V-Ray lights. Additonally, many manufacturers provide IES profiles for more specific light sources. Capturing accurate IBL probes is more complicated and there are different approaches to that.

b) You can compare your material to a known material to e.g. a VRscans material which is known to be physically accurate (well, as physically accurate as you can get today).

c) Practically all CG shots are adjusted in one way or another. It could be as simple as color grading, or adding bloom/glare, to more complicated stuff. Many of these are performed on the live action footage too.

Best regards,
Vlado

[stevejjd]

Thanks again Vlado