Region render produce different result when using Light Mix

[javierrentas]

Hi Guys
I have this issue all the time even with older versions of V-Ray 5. Right Now I'm using V-Ray 5.1.2.
As the title said when I re-render a portion of the image using region render, the new portion has a different light tone and does not match the rest of the render.

This is what I did?
- Make a render
- make some changes using Lightmix
- make a region render and render again

Any solution?
In the image, the first render has some warm looks and in the region render I got a cool look.

[nikoleta.garkova]

Hi javierrentas

Not sure if those differences are linked to LightMix at all - what if you try on a render without it? I made a simple test and I can't seem to reproduce the issue, as demonstrated here.
However, please check if the Auto Exposure or Auto White Balance options are enabled, as they might be causing such differences upon region render - see example.

If not, would it be possible to share a sample project file with the issue reproducible so we can inspect it? You can get in touch via our contact form, just make sure to mention this thread in the email. Thanks!

[javierrentas]

Hi Nikoleta
I had Auto White balance enable and that is why it was giving me different results. I guess I will not use Auto white balance anymore.

Thank you!

[konstantin_chaos]

Hi javierrentas,

Both the auto exposure and white balance effects are calculated based on the image being rendered.
When you select a region only the pixels in the region are taken into account.
This means that every time a new region is selected the Auto values will be different.

Because of that I'd recommend you do the following:

1. Render the whole image with the Auto EV and WB enabled
2. Apply them both the the camera using the Auto Values checkbox button. This will disable both options and will sort of bake the EV and WB to the cam parameters.
3. Render any region you like - the results will be consistent now.

Konstantin

[javierrentas]

I haven't think about that. Thank you!