Lights intensity on PBR Material

Questions
1

Hi everyone,

I’m reaching out to you with a question about lighting that has me a bit puzzled. Here are two scenarios:

Case 1: I have a basic scene with a ground that has no texture. When I add a light with an intensity of 2, it significantly brightens up the ground.

Case 2: In the same example, I change the texture of my ground to a PBR color. Suddenly, my lighting seems almost non-existent, and I have to crank up the intensity to 100 or more to get the right feel.

I suspect the PBR color might be the culprit… is there some kind of adjustment needed? Is this normal? Can you provide some guidance on this?

Thanks in advance!

PS: the capture without texture on the ground is at intensity 2.5, the capture with the PBR texture is at intensity 100.

case2
case1

2

Hi,
To answer your question without a PG and just for a starter, what I can say is this:

  1. In general, PBR materials are less reactive to light then standardMaterials (no mat being the default standardMaterial)
  2. In general, PBR materials take their light from the environment and the physical properties of the material. In particular, when not set any further, the metallic workflow. When importing a mesh from i.e. blender, materials are set to PBR (PBRMaterial). If unset, the metallic workflow is set to the default which is 0 for roughness and 1 for metallic (I guess). I’m saying I guess because I ALWAYS set these, at a very minimum (and so should you).
  3. In general, when a light hits a material, the intensity of the light on this material is worked through the material settings (the one receiving the light and not the light itself)
  4. In essence, the way a material reacts to light is different between standard and PBR materials.
    The light (color and intensity) is managed through the specular properties on a standard material. This same light on a PBR material is managed through a number of parameters (since PBR is much more complex) but, to simplify, essentially the intensity at which the light hits the surface of a PBR material can be modified though ‘directIntensity’ (material.directIntensity). This is the intensity of the light that will be added to the overall lighting of a PBR material when the light directly hits the surface.
    There are in fact many other parameters to set to diffuse the light, angle the light, etc. I encourage you to tour the doc which provide quite a number of information and insight on PBR materials for what’s supposed to be a rendering engine :smiley:. Also, use ‘the inspector’ in the playground, sandbox or in your scene to twist and tweak your light and materials for a better understanding.
    Finally, if you have a specific issue, try to provide a PG. It will provide a base and make it easier for us to modify and demonstrate.
    I hope this little piece of feedback will help. Have a great time with BJS and a merry Xmas and meanwhile, have a great day :sunglasses:
2 Likes
3

This is the part that might help understand the difference Mastering PBR Materials | Babylon.js Documentation

4

Hi,
Just back after a few days off, and catching up on your answer. First of all, I wish you all the best for the new year :smiley:

Regarding the lights, I haven’t revisited the subject since my return, but indeed, I believe the light settings on my PBR material might be off. I’ll start by looking into that.

Thanks for your feedback.
Have a great day!