Forums Technical Discussion Displacement Issues?

Displacement Issues?

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simonl
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Hi
I have this strange issue happening when using a displacement map where the image breaks up unless the bump is very very small.
Can anyone tell me what is causing this. Im using micropoly rendering.
The geometry has a uv texture node and then a material node applied.

Thanks for any help.

Simon

Attachments:
displacement_map.jpg (271.4 KB)

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anamous
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Looks like a displacement bounds issue. In your material (on the level shown in your screenshot), add a “properties” node and connect it to the next free material input. Then, from the gear menu on the top right, select “edit rendering properties…”. In the dialog field that pops up, from the leftmost field, select “Mantra10.0”->“Shading”->“Displacement Bound” and then click on the arrow button that goes from left to right. This will add the property to the node.

This property tell Mantra how far away from the original geometry to check for displaced micropolygons. Try setting it to something higher than the “displacement amount” value in your shader.

cheers,
Abdelkareem
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simonl
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Thanks for the reply.
I did what you said but Im not sure it made any difference. Im beginning to think this may be a bug? If I render closer to camera the problem gets worse
as you can see. If I render with the object some distance from the camera it becomes much less apparent.

see attached

simon

Attachments:
displacement_bug.jpg (282.5 KB)

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simonl
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I should also say Im using Houdini HD for Mac 10.0.282

Macpro 2.66 OS 10.5.6

Nvidia 7300GT

simon
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anamous
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Could you please post the file?

cheers,
Abdelkareem
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simonl
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I hope this helps. Im not sure how to include the textures though?
Oh and thanks for taking the time to look at this.

simon

Attachments:
displacement_bug.hipnc (302.9 KB)

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anamous
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Not sure what went wrong in this scene, but you didn't have a material, so your properties weren't applied to the object.

I simply created a material and put the shading nodes inside it and assigned it to the object. I don't have the original textures, so I used default ones.

cheers,
Abdelkareem

Attachments:
displacement_bug_210.hipnc (307.5 KB)
disp.jpg (130.6 KB)

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simonl
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Hi Anamous,
I reapplied my textures to the file you posted and the problem has now gone. Fantastic!
Im not exactly sure what you have changed to fix this. I can see that the displacement bounds has been increased to 2 but what else did you adjust
to get rid of that mess?

Regards

Simon
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