Chaos Corona Forum

Chaos Corona for 3ds Max => [Max] I need help! => Topic started by: mpavlos on 2015-07-20, 18:46:07

Title: AA around highlights
Post by: mpavlos on 2015-07-20, 18:46:07

Seen a lot of images in gallery with same problem and don`t have a clue how to fix that poor AA around highlights. In this image it`s just a sun with only 0.02 power. But the sun highlight is still very overbrightened. Even with Highlight Compress at 50 its still has a problem.
Any suggestions how to deal sun highlights AA?

Title: Re: AA around highlights
Post by: PROH on 2015-07-20, 18:53:18

Hi. You could try to set Internal Resolution (system tab) to 2 instead of 1 (default). It will render a little slower but will give better AA on highlights.

Title: Re: AA around highlights
Post by: mpavlos on 2015-07-20, 19:24:07

Thanks a lot!

I tried many things here, reducing MaxSampleIntensity to like 15-10-5; uprizing Light Sample Mult over 10 and higher, put AA balance to 2-4-6 and so on. Nothing work!

Here is image with Internal Resolution = 2. Still the same.

 

Title: Re: AA around highlights
Post by: PROH on 2015-07-20, 20:34:40

Yes, I see it didn't help. But I also see, that the highlight at the bottom of your render looks OK. So question is, why do the highlight at the bottom differ from the two others? Is it the same light they are reflecting or is the mesh build different? Or....

Title: Re: AA around highlights
Post by: mpavlos on 2015-07-20, 20:59:43

yeah, it looks ok, but it is reflections of those 2 highlights in fender. So this is not direct highlight but reflection of it, and somehow it looks good. 

Title: Re: AA around highlights
Post by: Ludvik Koutny on 2015-07-20, 21:05:59

Every single renderer will have problem with that :) No matter how many AA samples you do, if one pixel has value of say 500, and second one 0.5, even if you do many AA samples, the difference will still be big enough to create sharp transition. In real world, such super bright spots are usually covered by some bloom or glare optical effect. If there was some real camera, that could take photos without these secondary optical effects, you would see exactly the same problem even on real world photos.

So there are two options:

Sacrifice dynamic range of your image and increase highlight compression to some very high value.

Save the image as 16 or 32bit format, and use some post processing software to add bloom and glare to your image.

Title: Re: AA around highlights
Post by: mpavlos on 2015-07-20, 21:19:24

Ok, got it! Many thank Rawalanche!

I come up with idea :) Not sure if it`s possible but what if we can put a texture over sun to get a gradient with black edges and really hot dot in the center?

Title: Re: AA around highlights
Post by: romullus on 2015-07-20, 22:12:20

Gradient wouldn't help, because intensity in the centre would be still millions times brighter than everything else.
There was a talk somwhere on forum that at some time in future glare effect is planned for Corona, IIRC. Now that would be ultimate solution :]

Title: Re: AA around highlights
Post by: mpavlos on 2015-07-21, 07:15:55

Thanks a lot, guys! Really appreciated!