Environment lighting discrepancy between Corona 9 and 10

[Aram Avetisyan]

So the better filtering makes the image look inferior but we have to think of it as superior.  Got it

The new filtering technically gives closer look to the original HDRI used, the image looking inferior or superior is subjective here.

This smaller version is used for sampling the map (mostly for diffuse/mildly glossy surface). The original map is still used for highly glossy reflection/refraction/direct view.
Computing the map is expensive, that's why the lower resolution is used, to avoid high parsing times.

Previously the filtering was nearest-neighbor. Now it is linear. Sampling this way should better resemble the original, and it should also be able to sample more accurately.
The problem is with maps that have sun baked in it, which might have appeared as just one pixel (or not at all). This would lead to sharper shadows or missing shadows.
Now the sun is filtered, so the shadows are always there - but they may bet blurry.

This is a preparatory step for a bigger master task to be implemented in the future.

Using the string option will be the easiest fix here. Otherwise the decision about reverting back to previous filtering and waiting until the master task is complete and implemented should be discussed.

[dj_buckley]

It's not subjective though.  The user has spent time fine tuning his scene and getting the image to look as it did in V9, now he's rendered it in V10 and it looks completely different.  So now it no longer looks like how the user wanted it to look, which means it's inferior to his original setup.

The fact is you can't just change something behind the scenes that will fundamentally change the look of our work in a very significant way and not tell us about it.  And then when we discover it, expect us to be cool with it because it saves some parsing time.

If it's a 'prep step' and not the final goal, then it should absolutely be listed as experimental and come with a warning, because it's basically an incomplete feature.

[maru]

Hi all,

We understand your concerns, so we will address this issue ASAP. There is currently an ongoing discussion how to do it best.

Q1: Why was this change made? Why didn't we communicate it? Why isn't there a legacy switch?
A1: It was meant to be an improvement happening purely under the hood and it was not supposed to change the appearance of the rendered images.

Q2: Why is this changing the appearance of the rendered images?
A2: This is something we missed during our internal tests. Also, please note that no other users reported this to us during the daily / RC stage and we haven't encountered this issue when creating our internal scenes for testing new features, new versions, and presenting new features in the knowledge base/documentation portal.

The automatic downsizing of the environment map (for non-sharp reflections) has always been there (since alpha versions of Corona). We just changed the filtering method for the downsizing from nearest neighbor to linear filtering.

Currently, to revert to the original behavior, you can use a string option:
First, enable the development/experimental stuff rollout - https://support.chaos.com/hc/en-us/articles/4528523195537
Then, go to Render Setup > Performance > String options - https://support.chaos.com/hc/en-us/articles/4528609584017

And then, enter this line into the string options text field:

Code: [Select]

int lights.envResolution = 5000
If you wish to revert to the default V10 behavior, use

Code: [Select]

int lights.envResolution = 1000
 

[dj_buckley]

Thanks Maru

Personally I think the best way to address it would be getting it in a hotfix asap, moving it to experimental and letting the user choose which way they want it, but it should default to V9 behaviour.

[alexyork]

Thanks Maru

Personally I think the best way to address it would be getting it in a hotfix asap, moving it to experimental and letting the user choose which way they want it, but it should default to V9 behaviour.

This should be the way, surely. New scenes made in C10 could be the new way, older scenes should load in the old way. Renders shouldn't look visually different to this degree between major versions. Especially not if there's no warning popup (like was done with the "new" bloom+glare etc.) where at least you have a choice when you open a file made in C9 or older and can "upgrade" it knowing there will be differences.

[rowmanns]

Hi,

Will be addressed in the upcoming HF. Please bare with us.

Cheers,

Rowan

[Deckard]

I just noticed this discrepancy in one of my scenes and was just about to report it when I found this thread.
Attaching a comparison image for reference. The string fix seems to work, but a quick hotfix is certainly needed.

[TomG]

Hotfix 1 is out which addresses this issue. https://forum.corona-renderer.com/index.php?topic=40587.0 or straight to https://corona-renderer.com/download.

[Tom]

Thanks a lot guys 👍🏻

[maru]

Thank YOU for reporting it! 💪

[romullus]

Added legacy checkbox (in Developmental/Experimental Stuff settings) to return to the pre Version 10 filtering of environment maps. This is on by default for legacy scenes.

I would prefer this to be on for all scenes, unless new filtering brings significant performance gains. Looking at all those comparisons, Corona 10 looks inferior, IMHO.[/list]

[Tom]

I would prefer this to be on for all scenes, unless new filtering brings significant performance gains. Looking at all those comparisons, Corona 10 looks inferior, IMHO.[/list]

My bad, I read it too fast and thought the new filtering was off by default.
I agree 100%: what's the point in activating by default an option that gives worse results?