So many things…
It could help to have a test case.
Also I never used blender PBR as a reference, so there might discrepencies whatever you do.
I used unreal engine papers for the PBR shader and I use substance painter as a reference.
Note that there are plenty BRDFs you can use for PBR.
PBR is just a technique, it’s not as with phong lighting whereyou’ll have the same result everywhere. If blender doesn’t use the same brdf as we do, then it won’t look the same.
Also this wrong shading could very well be the same issue as the tangent issue and not related at all with the PBR shader.
What if you remove the normal map?
Defautl radius is 1 wich is kind of small, reflection and diffuse is offset according to this radius. Set it to 100 and you should be able to haev something similar to substance witht his studio env map.
Work in progress remember ?
Also at some point I want BoundingBoxes supported for LightProbe too, and the radius won’t have any meaning for a bounding box.
So the Api will aways be on the boundingVolume and not on the lightProbe directly.
EDIT : Though radius 1 is a bit low I agree :p.
The idea is that you are able to use several LightProbes in a scene with difference area of influence, and the shader will be able to fade between them. For now it only switch to the closest lightProbe, wich produce some flickering.
So just so I know. Do you have consistant lighting now?
For exposure, I’ve been thinking about it, I’m tempted to control the exposure through the AmbientLight, even if it’s not related to the shading model. But it’s not implemented.
For gamma correction we use pure ogl hardware gamma correction, and there is no way to set custom gamma. However users can configure this on the hardware level throught vendor software for harware management.