Why do these surfaces shade differently?

Hi there, maybe its a noob question but why are these adjacent surfaces reflecting light differently as if they have different curvatures? Is this a topology error on my part, if so how can i fix them? Thanks in advance

its visible on other rendering softwares too, most visible with this material

Hi Deniz- if the surfaces are separate, run the Dir command or ShowDir and see if the normals are opposite.
Feel free to post a file with the surfaces.


hey Pascal, i’ve rechecked it and normals seem to be the same: Here are the parts:
test_parts.3dm (570.2 KB)

Hi Deniz - I don’t see a discrepancy in Rhino - at least I don’t think I do - does this look correct to you?


Well, they do have different curvatures. There’s a clear kink between the larger bottom surface (green) and the first of the “strips” at the top (red), if that’s what you mean.

HTH, Jakob

There is a slight difference, which is much more noticable on materials I use in Keyshot

I guess you are right, how would you fix this (as close to this result as possible) and make it a smooth transition? I remember using blendSrf curvature options while creating this, which should’ve left no visible line in between surfaces, no?

Hi @Deniz_Ozen
Depending on what kind of transition you are looking for and where you want it, one option is to use “the pipe trick” to trim out an area from both parts and use BlendSrf to fill in the gap.
HTH, Jakob