General Phong shadow problem

[Thilo]

left c4d Nativ renderer (AR)
right corona

[maru]

This is as old as Corona, but it is bound to pop up once in a while...

https://coronarenderer.freshdesk.com/support/solutions/articles/5000516180
"Using low-poly curved geometry with strong bump/strong lights can cause jagged edges (terminator lines). To fix this, tessellate the geometry further with MeshSmooth or other modifier."

[VIVI]

It happens also with highres geometry when using sharp shadows like the sunlight. Of course I could subdiv the geometry to level 6 but that is not really efficient is it?

[atelieryork]

This is as old as Corona, but it is bound to pop up once in a while...

https://coronarenderer.freshdesk.com/support/solutions/articles/5000516180
"Using low-poly curved geometry with strong bump/strong lights can cause jagged edges (terminator lines). To fix this, tessellate the geometry further with MeshSmooth or other modifier."

Maru, no offense intended here but this isn't a feasible work-around to the problem, which remains quite a serious one. I have a very detailed, smooth, high-poly sofa object and sunlight moving across it appears jagged and rough due to this issue. Further tessellating it has no effect at all, and furthermore makes the scene unnecessarily heavy and slower to render. We have this issue on pretty much every project, and it's especially noticeable on cushions.

You can see it in the animation we recently shared here, on the last shot. It's subtle but only because we kept the camera far enough away. Had we done a close-up of that area you'd really notice it badly.

We spot this issue on many, many images other people post here in the gallery too.

You mentioned a while ago that this is something you guys are shooting for for a future version of Corona. Could you update us on if this is likely to be 1.4 or 2.x?

[Juraj]

I can add to what Atelieryork said.

I generally tried to work around this by using more subtle bump maps, but then they aren't noticeable at all. Subdivision actually works in my time every single time but the meshes become very dense. (to make the scene move fine I use turbo-smooth with 'Render time' subdivision, but of course, only works on perfectly divided meshes).

Can piss me off at time when I render hi-res close-up and notice the lines after 3 hours of rendering :- D

Another never resolved "feature" is the refraction and light. This issue always manifested with windows (with true, thick glass), but recently I noticed even bulb-like lamps wreak havoc on the scene.

[atelieryork]

I can add to what Atelieryork said.

I generally tried to work around this by using more subtle bump maps, but then they aren't noticeable at all. Subdivision actually works in my time every single time but the meshes become very dense. (to make the scene move fine I use turbo-smooth with 'Render time' subdivision, but of course, only works on perfectly divided meshes).

Can piss me off at time when I render hi-res close-up and notice the lines after 3 hours of rendering :- D

Another never resolved "feature" is the refraction and light. This issue always manifested with windows (with true, thick glass), but recently I noticed even bulb-like lamps wreak havoc on the scene.

Yep. I think these 2 issues are quite serious. I know we harp on about them a lot but for us they are top of our list of things that need sorting above all else. Speed is nice, added features are great too, but we need renders to be artefact-free and accurate. They're the main selling points of Corona for many people, after all. Sincerely hope they can be addressed in 1.x rather than 2.x.

[-Ben-Battler-]

Another never resolved "feature" is the refraction and light. This issue always manifested with windows (with true, thick glass), but recently I noticed even bulb-like lamps wreak havoc on the scene.

Can you link me to the relevant thread of this problem? It might explain some problems I had a couple of weeks ago.

[Juraj]

You have to hit up Maru because I have no idea :- )

[romullus]

Can you link me to the relevant thread of this problem? It might explain some problems I had a couple of weeks ago.

Here you go: https://coronarenderer.freshdesk.com/support/solutions/articles/5000516180-known-bugs-and-limitations

[maru]

Actually the "reflected refraction" thing is usually manifested by having dark/black, noisy areas in places where one would expect bright highlight. It is often visible on glossy floors if hybrid (transparent shadows) glass is used as window glass.