Lighting changes drastically during Interactive

[hurrycat]

Hi guys,

I am working on a small interior scene and I'm facing the following problem: each time I move something during Interactive rendering (small prop objects even, not lights), the scene lighting changes drastically, as if i had gone from +2.0 exposure to zero.
Unfortunately i cannot provide the scene, but i hoped someone had a solution to this.

Thanks!

[TomG]

Any chance of sharing a video, or stills? Any chance the scene can be cut down to something that can be shared, where it still exhibits the effect? Also, can you share which version of Corona, version of Max, any info about the scene that might make it unusual (e.g. third party plugins, or use of the Tone Mapping override), and whether this is happening just in that scene or in all scenes. Thanks!

[hurrycat]

Hi Tom, thank you for the quick reply. Apologies for the rushed, lacking in information post. Unfortunately I cannot share images but this happens in one scene as far as I can tell, not in other parts of the project.

I think it may have to do with the lighting setup: one plane light with 0,5 directionality directly facing the camera, with the light passing through several openings in a brick-like wall (to simulate a more intense natural light-not true to life but artistically it gave the desired result). It may be that the light is struggling and somehow it recalculates it everytime something is moved.

I know my info is scarce, but I will continue my testing and get back if i find anything. Thanks again!

[TomG]

TY for the extra info, understood that some things can't be shared (there is the private uploader, see signature, for anything that could be shared with us for bug fixing purposes without breaking NDA with your client but which couldn't be shared with everyone - but it may not apply of course :) ). I have no extra inspiration on the possible cause here at the moment (maybe someone else will though), my only thought at the moment is whether IR is set to use Path Tracing or not, overriding the UHD/4K/Path Tracing used in a final - can't see why it would make a difference, but maybe try enabling that override if disabled, or disabling if enabled :)

[dj_buckley]

There's a thread on here somewhere with videos showing this exact issue, can't remember the name of the thread though

[GeorgeK]

Hi guys,

I am working on a small interior scene and I'm facing the following problem: each time I move something during Interactive rendering (small prop objects even, not lights), the scene lighting changes drastically, as if i had gone from +2.0 exposure to zero.
Unfortunately i cannot provide the scene, but i hoped someone had a solution to this.

Thanks!

Do you experience similar exposure updates with production rendering just by re-rendering?

[dj_buckley]

There's a thread on here somewhere with videos showing this exact issue, can't remember the name of the thread though

Post #282 in this thread https://forum.corona-renderer.com/index.php?topic=33840.270

[hurrycat]

This is exactly what I am experiencing. I forgot to mention I'm on corona 7, Max 2021. I am between deadlines right now so I can't investigate further, but I will test is as soon as i find some time. Thank you all!

[maru]

There's a thread on here somewhere with videos showing this exact issue, can't remember the name of the thread though

Post #282 in this thread https://forum.corona-renderer.com/index.php?topic=33840.270

There are two possible reasons for this, which would be expected, but I am just guessing here:
1) UHD Cache - the UHD Cache is re-calculated when anything in the scene is moved (except the camera) and in IR it has some very low settings to calculate faster. So basically, the UHD Cache has low quality in IR and may flicker or have different brightness in IR and this is expected.
2) When changing exposure and re-rendering or re-running IR, you may experience this, and it is also expected: https://support.corona-renderer.com/hc/en-us/articles/4402317843345-Exposure-changes-when-I-start-rendering-

To verify if it's #1 - you can disable the UHD Cache and see if the issue is still there. If yes, then it is not related to the UHD Cache.
To verify if it's #2 - you can set Performance > Max sample intensity to 0 and see if the issue is still there. If yes, then it is not related to max sample intensity.

Other than that, please send us any scene where this is happening and instructions how to reproduce it, and we will find out what exactly is going on.