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The game engine will bake a lightmap which is a file texture of all the polygon face's interactions with light. It is important for depicting realism. Below is a tutorial for exporting your model as .FBX into Blender to package the UVs for lightmapping. As a side note, a separate UV set can be created for image textures such as a wood grain or marble texture, these allow for overlapping UVs but that is for another tutorial.
Step 1: Important! In Rhino or other modeling program, delete/remove or place on a separate layer all redundant construction items so they are not accidentally exported. Depending on your personal style of modeling, there might be a lot of extra surfaces hiding throughout. This should be a familiar process for submitting final drawings:
