Is UV Island Overlap OK?

Question

I'm pretty new to 3D modelling and texturing, so when I do a UV unwrap in Blender, I notice that it automatically places the UV islands in a manner that fills the UV bounds without any of the islands overlapping each other, and I typically see everyone else do it this way.

However, for the stuff I'm messing around with in Unreal Engine, I often want my one texture applied over the entire object so I'll grab all the faces from one side of my mesh, Project From View to get those faces on one island (I know I should probably be doing some mark seam stuff instead of this convoluted method, right?), then scale that individual UV island to fit the entire UV bounds, thus getting a "higher resolution" look for that particular set of faces.

I feel like I'm probably doing something deathly wrong by taking that approach, but my models turn out fine in the engine so I'm wondering what I'm missing, especially since leaving them all without any overlap means the UVs have to be very small and often look grainy on my model. What gives? I'd say my three main questions are:

1) Is UV overlap a problem for game assets, or texturing in general?

2) Is there a way more obvious, better way of accomplishing what I'm doing? I often have trouble with unwrapping cylinders and more complex objects with my method, so I'm guessing I need to invest some time into learning to mark seams better.

3) Bonus question if you're feeling generous: Will I need to be taking things a step further with things like baking textures for my uses in Unreal later on?

Answer 1

There's nothing wrong with UV maps overlapping. While it is difficult to say so for certain with all game engines, all of the game engines I have used have always been comfortable with overlapping UV maps.

Depending on what you're looking to unwrap, you may wish to use Cube Projection, Sphere Projection or Cylinder Projection instead of simply UV unwrapping by default. You can find these options below "Unwrap" in the "UV" dropdown.

You may also wish to use Smart UV Unwrap. All of these settings can be found in the "UV Editing" tab.

Of course, overlapping UVs could potentially be messy to work with, so some people choose to simply duplicate a part of the texture for a duplicate UV island in a different location.

For adding your textures into Unreal Engine, you will need to duplicate any pipeline you have in Blender. If you have multiple nodes running into a shader (e.g. Image Texture into Base Color & Noise Texture + Bump into Normal), you will need to replicate the same nodes using Unreal Engine shaders.

It is possible that you could bake the texture - however, keep in mind that you are baking the lighting as well, so this would likely only be useful for static objects with similar lighting to your UE4 project.