Author Topic: Shading issue  (Read 1972 times)

2022-05-11, 10:37:18

lollolo

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Hi there

Just got something that doesn't look right to me. Can you check it out?

Thanks and have a good day

C4D R20
Corona 8
Win 10

2022-05-11, 14:32:24
Reply #1

Beanzvision

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Hi there, how should it look?
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2022-05-11, 18:21:39
Reply #2

lollolo

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How it should look? I would expect a shading without issues. I think you have seen all these rectangles and triangles all over the place. None of them should be there.

2022-05-11, 19:21:20
Reply #3

TomG

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Which still doesn't answer what it should look like - the Fusion shader is being used to map something onto the surface, but from your one image we can't tell what, nor how that should look mapped across the surface. Maybe send the material itself over so we can see what is going in to the Fusion shader.
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2022-05-11, 19:29:42
Reply #4

lollolo

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Hi Tom

You can ignore these fusion shaders. I get the same shading issue when I have solid colors in Color/Gloss slots. And for Bump is only a single noise used.
The size of the rectangles and triangles are the same as the faces of my mesh. So It must be a shading issue.
So it has to do with Bump/Normal and the shading of it. It disappears when I deactivate Bump channel.

There is a zip-file under my first post,  you can download the scene.

Edit: Here is another screenshot. Only one noise shader in Bumb channel. Nothing else. I think it has to do with the size of the noise. In my case, it's only 2% world scale.
« Last Edit: 2022-05-11, 19:45:22 by lollolo »

2022-05-11, 19:48:42
Reply #5

TomG

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Ah didn't see it there in the first post, ty! Something to do with the way the object is created and mapped - deleting the UVW Tag stops the weird shading.
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2022-05-11, 19:52:22
Reply #6

lollolo

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Has nothing to do with UV. I have only one noise and this is set to "world". This means no uv is used. At least, it shouldn't.

Edit: It seems to me that noise set to "world" is broken in bump channel. Noise is set to world, but I get a UV seam.
« Last Edit: 2022-05-11, 20:01:29 by lollolo »

2022-05-11, 20:26:30
Reply #7

TomG

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To get it working I deleted the UVW tag, added a new one set to Cylindrical projection (per object, world system), and got what I would think are expected results. This object is also REALLY tiny, not sure if that is intentional (it is dwarfed by a default cube when added in to the scene, with the default cube being, I don't know, thousands of times larger).

EDIT Oh and I also reduced the bump value down from the 1000% too.
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2022-05-11, 20:30:44
Reply #8

TomG

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Having things at a real world scale is usually beneficial for Corona, so may want to try making this larger too. Anyway, here's the scene after those small mods, plus a render to show how small this little item is :)
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2022-05-11, 21:19:55
Reply #9

lollolo

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It is a bit too small right now, 17mm instead of maybe 25mm. It is small, but almost real scale, as this is small in real world too. I know, when it's too small or too big, strange things can happen during rendering. But I thought, this should still be in range.
I get the same result when I scale it up 10 times... That's not the issue, I think...

Another test: 50mm sphere, same material. Left sphere is not converted, right sphere is converted to a polygon object using c.
The left sphere (not converted) gives me the expected result. The second sphere which is converted gives me this shading thing again.
« Last Edit: 2022-05-11, 23:04:45 by lollolo »

2022-05-12, 12:40:59
Reply #10

burnin

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You can render with Physical or AR to get "correct" reference...
It'll also make it clear for others to reproduce what is expected.

2022-05-12, 12:57:08
Reply #11

lollolo

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Hi burnin, thank you for your reply.

I don't need AR to get correct references. Corona does that for me. Just not always.
My last screenshot shows how it should look like (left sphere) and shading artifacts (right sphere).

There is clearly an issue somewhere. Otherwise, both spheres would look like exactly the same, because they have the same material applied and have the same geometry.

2022-05-12, 13:21:06
Reply #12

Beanzvision

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Hi, Can you guess which of these is yours? ;) If I remove the UVW tag and apply a new one. It works!

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2022-05-12, 17:37:16
Reply #13

lollolo

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Hi Bean, thank you for your time.

I get what you are pointing at.
Like I wrote above, the noise is set to "World" and not "UV". In this case, UVW-Tag or projection should NEVER influence the mapping, because UV or projection isn't used. Noise set to "World" is 3D mapped using world coordinates.

But this doesn't work correctly. You can just change the projection of the sphere and "this shading issue" is gone. Like you did. But the problem now is, that noise in Bump channel doesn't use world mode. Noise set to "World" in color channel is working as expected. 
The behavior you described is correct, when UV or projection is actually used. But it's not in my example. Can you follow what I mean? 
« Last Edit: 2022-05-12, 17:43:32 by lollolo »