Artifacts on objects in UE, but not seen in 3DS MAX

Hello everyone. Noob here! :slight_smile: I am still learning UE and modelling, therefore sorry if I ask something trivial.

I have made an object that i would like to use in UE.
When I import it, there seems to be artifacts, dark incorrect shading appear on the surface.

Basically what is happening is that in 3ds I apply a chamfer modifier to the green object which makes it smooth. I do a render in arnold where everything looks okay.
Before rendering I apply an UW unwrap for proper tiling etc, and then I apply a normal modifier to Unify the normals.

After that I export to FBX and then “import all” in UE.

The material is a simple base color without anything and roughness down to 0 to make it shiny.

As having proper UVs, i beleive this has to be narrowed down to geometry but if thats the case why it is not coming to surface in 3ds?

Thank you in advance for any help.


It’s going to be your lightmap uv!! You see those tiny thin “lines” on the uv area? That is your problematic part! Every island calculates separately and then put together as a MAP!! So wherever you have a cut in your uv map/island, you’ll have a high possibility to have errors /black lines/ in your lighting!
Have your cuts where it’s either not visible or at hard edges!! The rest keep together!
…also raising the lightmap resolution can help…

Hi! Thanks for your answer. Well, the seams were generated automatically, however I see what you mean. The chamfer effect smoothens the edges by inserting small faces, and those faces are getting as lone islands on the UV map If I am not mistaken which have different normal vectors calculated even they are next to each other directly?
Coming out from your words it seems it is a manual edit now to solve the problem, probably by putting the seam edges somewhere else than the smoothed edges?


The final solution was to increase the UV resolution for this object only to 2048, and also redrawn the seams and used less segments of chamfer that is still smooth. but all this together removed the artifacts.