How can we Keep glossy reflection of the sun, by hiding the sun disc (car model)

[cecofuli]

Hello
as we know, when we render an exterior project, with CoronaSun, we have the boring problem of the sun disk.
Often, we have a bright pixel. This effect can be neglected in still images, but it translates into an annoying flickering in animation =(
Ok, I can tick "visible in reflection", but we will lose a nice glossy effect on my car shader. See the images



What do you suggest to do?

[tomislavn]

Tried rendering with HDR instead of sun/sky?

[cecofuli]

Yes, I could an I'll try to do as you suggested. But I think Corona shouldn't have this problem.
As V-Ray, CoronaSun and CoronaLights need to separate REFLECTION vs SPECULARITY
   

[maru]

How about changing sun size or sky settings?

[cecofuli]

Same problem:  more bright pixels. And soft shadow thanks to the new Sun-disk size.
But, some years ago, we had the same problem with V-Ray. And Chaosgroup added a "affect reflection" and "affect specular" option for the lights.
In attachment some frames.

[Ludvik Koutny]

Path tracers can not differ between reflection and specular. I would try to lower GI/AA balance first, so fine geometry with reflection gets sampled better and highlights do not flicker. Once you get your highlight, it will look like bright sharp dot. You need to apply some glare on it so it looks realistic. That one firefly on the shadowed side of the car is weird though... did you change MSI?

Here's how a picture of a car on sunny day looks like

You get these glares on places where fireflies are. The big problem here is that corona doesn't have any glare yet. And the problem has gotten a lot worse since internal res now defaults to 1.

[cecofuli]

No, everything is by default.  =)
Maybe Ondra can try to solve that problem.
It's very useful to have reflection and glossy separated. Not only in my scene, but also in Studio setup.

[romullus]

How about to render separate reelements and then clamp brightest pixels in reflection pass?

[cecofuli]

Avalanche, I see =) But, often, in CG we try to be closer to reality, by giving up small effects =)
Romulus: interesting idea, but I would like to see if there is a possibility to get good beauty pass, without tricks =)
In V-Ray is possible ;-)

[Ludvik Koutny]

Try to save image in 32bit EXR, and apply glare it post, there are plugins that will generate glare of correct realistic intensity from those bright spots. If you need free software, then try lens blur node in Autodesk Composite. Or you can try http://www.randomcontrol.com/arionfx-for-photoshop ArionFX, which is plugin photoshop designed specifically for this. It's really great companion for physically based renderers, where you render physically correct image, and then apply secondary photographic effects (bloom, glare, vignette, camera response) in post. And 95EUR is very reasonable price :)

[cecofuli]

Rawalanche: thanks a lot for the suggestion. Price isn't a big problem. But I'm working for animation ;-) So, I cannot use ArionFX. I hope Ondra will fix this problem )

[Ludvik Koutny]

Rawalanche: thanks a lot for the suggestion. Price isn't a big problem. But I'm working for animation ;-) So, I cannot use ArionFX. I hope Ondra will fix this problem )

What do you use to postprocess your animations?

[cecofuli]

AE with standard filter, noise reducer plugin + Magic Bullet Looks. Not so much =)

[Ludvik Koutny]

AE should have some glare effect. If not, you can make one yourself. Make sure you use 32bit workflow (set up in AE properly), then key out luma channel, duplicate it two or three times, and motion blur it in several different directions. That will give you glare streaks, then do one more, and just blur it, to get little bloom around the hotspot :)

[cecofuli]

Rawalanche, if you open my animation, you see how much the  bright pixels change position. With glow effect I will no solve that problem =(