Displacement shadows(?)

[piotr_antonibieluga]

Hi everyone,


Thanks for tuning in.


I have been working on a few projects recently and I get this recurring issue:


When I apply a displacement map (textures from Poliigon) to a solid group, while being rendered it creates strange shadows such as the ones on the image below (that face is completely flat). This happens frequently and gets even worse when rendering with CPU instead of CUDA/RTX. Strangely enough the same issue happens when rendering with ChaosCloud, so the mistake must be in the model. Whether the Tri-planar projection is on or not seems not to have any effect...

I apply these textures through the 'apply to selection' option in the Vray window and make sure there are no other materials. This example is in a brand-new file that I created, so no other interference (attached here: https://we.tl/t-dRBVoSy9bx). You'll notice that in some areas there is a black trim on the edges - again, caused by the disp map.





Does anyone know a cause or a good solution to this problem?


Many thanks,
P-

[nikoleta.garkova]

Hey piotr_antonibieluga,

Try subdividing your geometry a bit more to see if those are cleared out. This has been previously discussed in the following forum post, see if the proposed helps.

[konstantin_chaos]

Hi piotr_antonibieluga,

The reason for the unexpected shading of the mesh has to do with the mesh topology combined with the Keep Continuity option.
If for example disable Keep Continuity the shading will go back to normal.
Option 2, as Nikoleta suggested, is to modify the mesh topology to avoid this artifact but this can unfortunately be time consuming.
Here's an example of how the geo should be modified:


Another thing I want to note is that you most probably don't need displacement in this particular case.
A good normal map will look just as good.
You'll only maybe see a difference at sharp corners and around the silhouette of the object.

Lastly this issue caused by the Keep Continuity option is something that can potentially be addressed in the V-Ray Core.
I'll log a ticket in our system and the devs will investigate ways to improve it.

Thank you for bringing my attention to this,
Konstantin