Hi,
I rendered the same scene with Corona 9 and Corona 10 and saw a massive difference in the render in term of lighting.
The scene is lit by an HDRI and there’s a real difference in the rendering of the shadows: they are sharp in Corona 9, and blurred in Corona 10. So basically all the lighting rendering changed from Corona 9 to Corona 10. It’s as if there was a Gamma correction applied to the map in Corona 10.
Here are some crop renders showing you the issue, and the HDRI settings:
Hi,
Do you have ACES OT operator in the Tone mapping?
If yes, please try disabling it and see if the results are identical.
I’ve seen many reports of this, renders looking quite different.
Are you using Corona Sky with clouds enabled in this scene?
No I don’t.
Really? That’s interesting. I found Corona 10 new features being pretty awesome, particularly additional outputs in maps and the new lister, these are really cool, but in this particular scene I had to lower the gama of the HDRI by around 15% in order to obtain pretty similar results to Corona 9, which to me is not “quite different” but drastically different. So in the end, I may have to roll back to Corona 9 until a fix is released.
No: only an HDRI map in the ‘single map’ slot of Corona’s Scene Environment settings
It’s worth mentioning that Corona 10 seems slower to render than Corona 9, at least in certain situations like this one: https://forum.corona-renderer.com/ How to optimize my scene to render faster? ;all
Hi,
Please attach the scene archive (or a simplified version of it), if possible, for us to have a look.
The renders should not look different between v9 and V10.
The best thing, of course, will be to send a ticket to us at: https://support.chaos.com/hc/en-us/requests/new
and attache the scene there. This way everything will be tracked better.
Messing with the gamma is arguably one of the worst things you can do with environmental HDRI, no wonder why your renders are different in Corona 9 vs 10
Thanks. I just opened a ticket and sent the scene.
He means he had to adjust the HDRI gamma in order to make the renders match between 9 and 10. So in V9, the HDRI at default gamma settings gives render A, in V10, the HDRI at default gamma settings gives Render B. This is where the difference is. To make Render B match Render A, he had to adjust gamma of HDRI.
Edit: I think.
@dj_buckley: thanks, you’re absolutely right. This is what I meant.
Changing HDRI gamma would explain the difference in shadows in the first post. I find it hard to believe that with default gamma V9 and V10 would produce such vastly different results. Anyway, now that the scene is in the hands of support team, i’m sure we’ll soon hear what’s the real issue here.
Just to clarify: I didn’t change the HDRI gamma. I used the exact same scene with same settings. But, as you can see in the SME screenshot, a color correction is applied to the HDRI. And this color correction remained exactly the same in both renders, hence I’m surprised of the difference.
The case is already being handled in the ticket, the difference between the renders is confirmed.
It has something to do with CoronaColorCorrect map, plugging the HDRI directly in to the Environment slot(s) gives identical renders for V9 and V10.
I will share other important updates here.
Oh, if ColorCorrect node produces different results with HDR images, then that’s pretty much a ‘no’ for using v10 for me. Using it in almost every scene over here. Sounds like something for a hotfix.
Same 
Here are the updates for this:
The environment map filtering has been improved in Corona 10, and with some specific maps and resolutions the renders may look different.
As observed by Tom, there is no difference when using a 20k map and there is difference when using a 7k map (different maps).
If this is the case of any user, to have identical with Corona 9 renders while using Corona 10, a string option can be used to increase the environment map’s lighting resolution (default value is 1000):
int lights.envResolution = 5000
This should give identical results between Corona 9 and Corona 10.
Feel free to test this out and share your feedback.
Seems like a key change that should be documented somewhere.
I’m not technical so I don’t fully understand that string, but is Corona ultimately reducing the resolution of HDRI’s behind the scenes?
