question

Nicolas Favereaux avatar image
Nicolas Favereaux asked

Black shadow/edge/outlines problem with bump and displacement

Hi,

I have a problem sometimes with Arnold on Cinema 4D.

When i'm using bump, i'm getting black edges/outlines on geometry with Displace.

capture-decran-2020-11-11-130705.png


I've got a floor using a displacement map and arnold tag.

Whatever is the setting i use in subdiv and displacement the problem is still here.

The only thing that makes it disappear is cutting off the bump or put it to 0


Here is a screen with bump on with 0.001 cm :

capture-decran-2020-11-11-131053.png


Without bump :

capture-decran-2020-11-11-131150.png


My bump is a layer RBGA that mixes 2 C4D Noises.

I Tried to plug only one C4D Noise directly, same problem. Same thing with an arnold noise.

I already had this problem on a pyramid without any displacement and other occasions. My bump is always problematic. Same problem if i use a texture image for bump or even a normal map ...

My only temporary solution is to bake my displace into geometry. When i'm doing this the problem is almost invisible, i can see it in some occasions but i can't find a real solution.


Thank you in advance.




renderc4dtoadisplacementbugnormal map
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Connor Paterson avatar image
Connor Paterson answered

Hey,

I've had this one in the past.

I found that sometimes when applying bump to low poly objects. You can get artefacts similar to what you have, show up on the glancing angles/edges of the geo. I think the normals might be getting a bit screwed.

I could totally be wrong, but maybe try bumping up the object's subdivs a little and see what you get. It might be worth a shot, as the object looks a little low poly at the moment.

1605109711894.png
I think you can a similar result from having the bump too high, though I don't think it will be that this time around having seen you're screenshots.



1605109711894.png (174.8 KiB)
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Nicolas Favereaux avatar image
Nicolas Favereaux answered

Hi,

Thank you for trying to help :)

Unfortunately whatever level of subdivision i put in the arnold tag, the problem persists ...

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Connor Paterson avatar image
Connor Paterson answered

Sorry, I meant the actual objects geometry subdivisions.
Opposed to the rendertime subdivs :)

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Lee Griggs avatar image
Lee Griggs answered

Does it happen if you apply the shader to a different object? Can you upload a simplified scene somewhere?

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Nicolas Favereaux avatar image
Nicolas Favereaux answered

Connor,

I tried to increase by 4 the level of subdivision of my mesh, directly on the geometry, the black shades are less visible but there's a lot more of them ...capture-decran-2020-11-11-185701.png


Hi Lee,

Thank you for joining the help !

Here's my file, this is just my plane with my shader and the texture for the displace.

https://drive.google.com/file/d/1H9-IkHpbvOK9c5uAEQuJ_B1ucjaBXKn7/view?usp=sharing

I tried to put the texture on the puppet model (without the displace) and yes the problem appears on it.


Thx !


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Lee Griggs avatar image
Lee Griggs answered

Hi, nothing renders. Can you just assign the shader without texture maps to a sphere, please?

1605167427817.png


1605167427817.png (208.2 KiB)
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Nicolas Favereaux avatar image
Nicolas Favereaux answered

Hi Lee,


Here is my shader on a sphere without the displace, i can see the problem if my sphere is low subdivided but it's very subtil. It's really obvious when the displacement map is on.


PROBLEM_BUMP_ARNOLD.zip


1 comment
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Thanks for the scene Nicolas, we're looking into it.

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Nicolas Favereaux avatar image
Nicolas Favereaux answered

Hi,

Lee, by any chance did you have time to take a look at the shader ?

I'm sorry, i'm out of solution for this problem ...

2 comments
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Peter reported it to the team yesterday. There is a ticket for it now. Thanks for reporting Nicolas!

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That's great thank you very much.

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Bhuwan Sharma avatar image
Bhuwan Sharma answered

Try disabling autobump in the displacement shader.

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Nicolas Favereaux avatar image
Nicolas Favereaux answered

Hi Bhuwan,

The autobump is already off :/

But thx for trying to help me !

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