Plane meets curve render issue

[trillerans]

Hey Guys,
quite new to Corona here and I find it pretty good overall. I am stuck with an issue that I can't really understand: the geometry you see below gets rendered very weird with a strong shadow coming out of nowhere where the plane meets the curve.

Any idea why is this happening?

[TomG]

I can't really tell what I am looking at in terms of geometry from the screenshot. Might be best to send in the scene.  Is the object with curved end raised slightly above the curved background, to avoid co-planar geometry? Overall, it looks like some issues with smoothing, which I believe is the Phong tag in C4D. Another thought is that everything really should have some thickness, just like reality nothing is ever zero thickness, but it looks like the curved object has zero thickness, so that might be an issue too.

[trillerans]

Hey Tom,
thanks for taking the time to answer. I finally got it working but unfortunately the problem was not as simple as a Phong Tag or the thickness itself. It turns out that I had to cut with the knife tool the curved section just like you see in the screenshot below.

I don't know why this happened and what baffles me is that this did not happen in the Standard/Physical render.

Anyways, thanks for your help.

[TomG]

You can always send in the scene with a bug report, since it looks like the scene wouldn't have anything "unshareable" in it (that is, clients wouldn't want it shared, etc.). See https://help.c4d.corona-renderer.com/support/solutions/articles/12000033461-how-to-report-issues-c4d for how to open a ticket/post a bug on the forums, and a link to the private uploader if you want to keep the scene for our eyes only :) That way we could take a look into the geometry and see if it highlights anything about Corona that needs changing or fixing.

[Nejc Kilar]

Hey trillerans, I'm curios... Does this happen only with the Interactive Renderer or also the final render?

[trillerans]

Yes,
it happened with both interactive and final render...

[burnin]

It is strange...
Was that mesh imported? Does it have Normal Tag?
Because no Cinema's object rendering with Corona doesn't expose this issue (at least, it shouldn't).
But I know that few other tools and render engines show it on geo with long polys and cutting is a must.