Mirrored reflections (glossy vs blurry) renders wrong (Commercial ver 3)

[tennet]

Hi,

Using the new commercial version 3. I'm rendering some bottles on a glossy surface (glossiness 1,0) and to me the glossy mirrored reflections look correct, but when I add some roughness (glossiness 0,8) to the surface then the mirrored reflections start to show the glass thickness and the reflection loses all the contrast. It doesn't look right... the blurry reflections should look like a "blurry version" of the glossy reflection, and it shouldn't show the glass thickness like in attached example.

I did a test using "Glossiness 1,0" and added a tiny C4D noise to the surface instead (to get the same blurry effect) and this renders correctly. Big difference.. See attached examples.

So I think there is something wrong with the glossy reflection parameters.

[houska]

That's interesting... Could you post a testing scene where that happens?

[tennet]

Hi Houska,
Yes, can I share that with you only?

[Beanzvision]

To me, it looks like the "liquid" mesh isn't intersecting with the "bottle" mesh. Is the liquid slightly larger than the bottle?

After a test, that's irrelevant. I also get the same results as the OP when decreasing the glossiness to .99.

[houska]

Hi Houska,
Yes, can I share that with you only?

Oh yes, just use the "Upload bugreports here" link in my signature

[houska]

Or maybe you don't have to. Seems like Ben already reproduced it :-)

[tennet]

To me, it looks like the "liquid" mesh isn't intersecting with the "bottle" mesh. Is the liquid slightly larger than the bottle?

After a test, that's irrelevant. I also get the same results as the OP when decreasing the glossiness to .99.

Great! Thanks Ben, yep that's the same result.. Solid reflections (when not using bottles or other refractive objects/liquids) seem to render correct, but as soon as there are refractive objects and 'Glossiness" below "1.0" then it happens. I guess the "blurry" reflections should look more like my example above, where I was using the tiny noise in the bump channel. No loss in contrast and all details are still there, but blurred.

This is kind of a big deal for me right now, hope it can be addressed quickly. Thanks!

(Yes, the liquid mesh is larger than the bottle, it's intersecting the glass by some millimeter)

[TomG]

Is this not one of the known limitations regarding glossy reflections listed on https://help.c4d.corona-renderer.com/support/solutions/articles/5000516180-known-bugs-and-limitations ?

And does enabling Caustics resolve it?

[Beanzvision]

Is this not one of the known limitations regarding glossy reflections listed on https://help.c4d.corona-renderer.com/support/solutions/articles/5000516180-known-bugs-and-limitations ?

And does enabling Caustics resolve it?

Actually, I believe it is. And yes, caustics does resolve it. At least for me. Good spotting Tom :)

[tennet]

Yes Tom, enabling Caustics solves it for me also (enabling 'Caustics (slow)' for both the glass and liquid material).. is there any cheat "Caustics (FAST!!!)" that I can use instead? :) I'm not after any caustics effect in my render and enabling this option makes my (already) slow highres render take ages...

I didn't know of this "Known bugs/limits" page, but it seems to be some issues there with glass, lights and refractions. I'm not a programmer, but I really hope you can come up with some "cheat workaround" option to get the same blurry effect WITHOUT needing the 'Caustics' enabled.

[TomG]

Well, any fix will be pretty fundamental. There won't be some odd "Caustics (fast)" mode - but, caustics is being totally re-evaluated already, which may have a bearing on how fast they are, may even have a bearing on how glossy reflections are handled, we will have to wait and see in the development of Corona 4.

As for the overall glossy reflection issue, as a known issue it is something we would like to fix, but as noted it is fundamental and would require proper, complex reworking of some light transport stuff going on in Corona - which is not to say we don't want to do it or it will never happen, just to say don't expect a quick bandage fix for it (which would probably mess a lot of other things up), if it is fixed at all it will likely be fixed properly and fully!