Render output looks completely different from the file saved yesterday.

[lanair]

Hello,

I saved a file with clay and light settings a few days ago. It rendered like the first image attached below where everything seemed ok.
When I reopened the same file (and cross checked with all the autoback files), they render like the second image.
I haven't changed any settings. The gamma value looks ok.
The exact same file which rendered ok a few days back has turned into a train wreck.

The file has around 8 cameras for night settings and they render with this kind of lighting now.

I tried importing this into a new max file, changed tone mapping but the lighting still looks off,
uninstalled and reinstalled the render engine but there is no change in the render output.

Kindly help resolve this with urgency.

Thank you.

[romullus]

Hi,

Do you have lightmix set-up in the scene? Maybe you baked lightmix values to the scene without realizing that this will permanently change the lighting?

[lanair]

Hello,

I'm pretty sure I do not remember baking lightmix into the scene.
I didn't know that it was even possible, I had to just look it up to know what it meant.

I also went back to check the Auto back files, that was saved much before the file attached above,
each file had a different outcome from the original render, mostly along the same lines,
two outcomes are attached below, third is the original render for comparison.

Thank you for your time.

Kind regards,

[Avi]

Hi,

It would be best to send us your scene by starting a ticket with us so we can have a quick look : https://support.chaos.com/hc/en-us/requests/new

[TomG]

Quick questions and thoughts - what is the fire, an openvdb? A Phoenix sim?

Also, there's no Tone Mapping Control used any place is there, where restarting a render is needed to see the effect, so, e.g. you could adjust tone mapping and save the image getting one result, close the scene, never having re-rendered since adjusting tone mapping, reopen it later and the Tone Mapping Control would now take effect and the render would look different.

[lanair]

Hello,

The fire was just a plane with a jpeg, with a corona light mtl.
I did use tone mapping as I always do for all my renders and this scene was tested over a span of three days where everything looked normal.

It rendered oddly for the next three days as the images attached above (in the first post), which is when I decided to post into the forum here.

I will be sending the file to chaos shortly.

Update : The file has been sent to chaos. I will update this post with their response once I receive it.

[Aram Avetisyan]

Random though: maybe you have changed the system units (by opening another scene or simply changing them) and when opening this scene back again, you did not adopt this scene's units? This can cause misinterpretation of lighting objects size (including lightmtl objects) which can affect their lighting too.

But from the first glance, it seems a tone mapping/color management issue.
Please check if you have Gamma workflow or OCIO in 3ds Max color management.
If you have OCIO, then the result in Corona VFB is linear (not like what you would see with Gamma workflow, even with tone mapping). If you have gamma workflow, then it should work fine.

In any case, try changing the Color management settings just to see if you are able to get any of the results (original or the modified one) with any of the color management settings.
If you are able to consistently get them, then we will be sure that this was from sudden change of color management settings.

[Avi]

The user said in ticket, the issue was resolved automatically for her.