Ok, so here is my correction for the first post:
I've tried many different render settings, except this one...

Edge length 1px solved the problem.

Thank you thomthom!!

I hope everything is in the zip

disptest.zip

Yes, irradiance + light cache. I tried to change subdivs, samples but that noise is still there...

This is my displacement map:


I've tried different images and different image sizes with the same result...

Here is my visopt
displacementtest.zip

Hi Everyone,

Please help, I have a problem with displacement renders.

I'd like to render a standing seam metal wall panel with a displacement map. I've tried many different images for disp. map and different render settings but those strange spots and noisy lines were always there.

Sometimes the noisy area disappears when I change the viewpoint, but in most cases only the "position" of the noise changes.

How can I get rid of those spots and lines?

Thanks a lot!

Attila