In Blender, a sudden change of colours is happening in my render. Why?

[happysmash27]

In my render which I am making in Blender, I am getting a strange and sudden colour change:

I thought this may be due to the Tonemapper, but even after changing it from Linear with automatic adjustments to Camera Settings I still get the same sudden change.

My Imagepipeline uses OpenCL, Tonemapper with Camera Settings, Bloom on default, Vignetting on default, and Color Aberration on default. I would use motion blur, but I was actually able to pinpoint some issues to it, so am no longer using it. Even when I turn Bloom, Vignetting, and Color Aberration off, I still get the same effect.

My Blender Color Management is set to Filmic with -2.5 exposure, 1.0 gamma, Base Contrast, and Filmic Log as a sequencer. Changing the Color Management to default settings does not seem to get rid of this sudden colour change either.

My scene consists of a sun, the default sky, and a very large Icosphere with the Null material and homogeneous volume. Disabling the homogeneous volume seems to stop this from happening, but I would prefer to keep it enabled. Does anyone have any suggestions for fixing this while still having some volumetric lighting?

[Dade]

It can happen with auto-linear tone mapping but it shouldn't with just linear and fixed tone mapping. Can you post the scene and pin point the 2 frames where it happens ?

[Fox]

The last 2 frames are more yellow - orange. Most likely from bright light like sun.

What if you disable null material? I was doing another day some laser camera lens setup and the null material doesn't use volume ior at all, it goes through ior 2 volume like it's 1.

[B.Y.O.B.]

Maybe the camera volume auto-detection is failing in a few frames, possibly because of incorrect interior/exterior volume definitions or flipped normals or other malformed mesh geometry?
Just some ideas. A scene would really help.

[happysmash27]

The file is rather large, but it is available at https://happysmash27.me/Upload/Destroy.blend. The most noticeable change occurs at frames 593-594, but other changes occur as well.

[happysmash27]

Changing the Icosphere to a glass material with the IOR of air, there is now a drastically different image on frame 591 compared to after.

[Fox]

Perhaps MLT is not finished it's high variance with scattering, or was this random int?

[wasd]

With camera volume:

Without camera volume:

My scene with the same problem:

camvol_bug.zip

(2.91 MiB) Downloaded 278 times

I guess, something's wrong with camera volume. It never works for me, so I just disable it.

[Dade]

I guess, something's wrong with camera volume. It never works for me, so I just disable it.

I'm looking at your scene and it works fine if I replace the "mattetranslucent" material with matte so I have the strong feeling the instanced leafs are just not "well formed": the must enclose a volume of space without holes and with normal pointing in the right directions.

It is pretty much impossible to check if the hundreds of leafs are "well formed" for me, can you reproduce the same problem with just a single cube ?

[Dade]

The file is rather large, but it is available at https://happysmash27.me/Upload/Destroy.blend. The most noticeable change occurs at frames 593-594, but other changes occur as well.

I'm testing this scene at frame 593:

and 594:

It seems to work fine on CPU and with AMD GPU however I get a driver error with NVIDIA. Are you using CPU or GPU rendering ? Can you try if CPU rendering works fine ? It may be a driver problem.