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Hi Elele,
could you share a simple scene, with all the assets, that shows the effect, to better investigate the issue?
ciao beppe

Don't want to throw any confusing comments into the ongoing discussion here, but it is strongly recommended to only use one of the two methods.
Either bump or displacement mapping - both probably will produde the hiccups you are experiencing.

TRRazor wrote:Don't want to throw any confusing comments into the ongoing discussion here, but it is strongly recommended to only use one of the two methods.
Either bump or displacement mapping - both probably will produde the hiccups you are experiencing.

Well yes, I want to use both bump and displacement. That is my problem. Both alone don't give errors.
Is it not possible to have both bump and displacement?

bepeg4d wrote:Hi Elele,
could you share a simple scene, with all the assets, that shows the effect, to better investigate the issue?
ciao beppe

I can't share the original caus it is for a commercial product.
I recreated it with another scene. Just a 100cm sphere with 20 segments and 20 sides with this image as both bump and displacement.

Is it not possible to have both bump and displacement?

Technically: Yes, but OctaneRender unfortunately has problems combining both methods (this is supposed to get fixed, some time in the future, from what I could draw from developer comments here on the boards)

Hi Elele,
it's possible to use displacement with bump, but it largely depends by the geometry topology, not having overlapping UVs, and by the quality of textures.
Using the same texture for both channels does not make much sense, in general we want a displace map for deforming the geometry and a bump or normal map for adding the fine details.
One way is to combine both textures in PS or similar, or you can try with the mix material method, here is some example with your texture for displacement plus another one for bump: P.S. If you see strange patterns when you use displacement, especially when used with bump, try to play with the Ray Epsilon value, it has a great impact in the final result
ciao beppe

Like I said, I can't share the original textures since they are for a commercial product I'm making.
The image i gave you, is so you could recreate the error like you asked. Which you did in the first image.
The original images I use are different from each other, the bump is for detail, the displacement is for deforming geometry and they are both as high quality as possible for an image.
Since the error happens for my mesh, DAZ3Ds G3F and a basic sphere I think it is safe to assume the problem is not related to the mesh or UVs. The mix material trick doesn't work, like I showed in the previous example.
Guess I'll just photoshop it then.

Since the error happens for my mesh, DAZ3Ds G3F

Combining the two methods on a DAZ3D human character figure doesn't work at all.
We've tried this extensively during our RedSpec TGX skin shader research - so far it only produced errors.

We've introduced displacement mapping first with our RedSpec TGX Hair shaders, but while keeping bump mapping mostly disabled, when relying on one and the same map.

Can you combine normal maps with displacement?

You can combine anything with displacement, as the "mix material" node has a displacement pin!

So make your standard material with normal maps, pipe it through a mix material, using it on both inputs, and apply the displacement there.