Sketchfab Forum

Environment Lighting Technical Problem

(Shaderbytes) #1

Hey guys

I noticed a weird smallish but prominent spot on two places on one of my models thinking it was caused by me I went to check the textures and found it was not. I then discovered it was been caused by the environment lighting.

environment_liighting_spot.jpg1920x1080 189 KB

I know you are using the hdrlabs stuff but now I am wondering if you are using a dual environment setup? The sIBL collection includes a blurred low-res version of the environment to use for diffuse lighting calculations and the hi-res normal version is only used for reflections.

I presume this spot is been caused due to using the hi-res ( or non blurred ) env map for diffuse influence? If not Im interested to know what is causing this artifact.

In blender cycles this is the node set up for environment lighting using two maps as explained above :

Manual-Cycles-Env-Trick-Nodes.jpg854x504 57.1 KB

#2

Hmm, I don't know.

Are you able to reproduce it in another model?

(Shaderbytes) #3

It's definitely not in the texture , nothing weird in the geometry either and it can be seen as a direct result of turning the environment on/off. I dont know the technical details of how your rendering engine works so I cant say it something else in the model is aiding the error.

I will make a simple test with a flat plane and report back here

#4

I also noticed that if you rotate the environment, the spot doesn't move at all. Almost like there's a hole in the top of the sphere?

(Shaderbytes) #5

very strange .. here is the model with normals in Blender , a sample of the UV charts .. each side has its own and the texture :

environment_liighting_debug.jpg1590x2000 952 KB

(Shaderbytes) #6

the problem is not in the reflection influence but in the diffuse influence. Diffuse would not change when viewed from another angle so this makes sense that the spot does not move .. because the model and environment are static- only the camera is moving.

(Shaderbytes) #7

ok I can reproduce the issue with a simple plane and half sphere I just created.

debug environments by shaderbytes on Sketchfab

I have set the material reflection to zero and switched off all other material options. These materials have a color of #E7E7E7 at 80% no texture .. as simple as you can go.

you can even change the environment to popcorn lobby or food print court .. the spot remains dead center on the sphere.

(Shaderbytes) #8

Here is another example .. this time I duplicated the sphere and rotated it 30 , 60 ,90 degrees positive and negative to the left and right ( view the wire frame to see what I mean ) The spot does seem to always be at the apex of the sphere.

debug environments 2 by shaderbytes on Sketchfab

#9

Thanks for the super thorough testing!

(Cedric) #10

Thanks a lot for the report, we know what it is and it should be fixed in next major version of the rendering, around the beginning of march. Keep the model online online we will use it as a test. thx