3D Texturing UV Mapping & Unwrapping Flashcards

What is the difference between 'planar' and 'cylindrical' UV projection?

Answer: Planar projects from a flat plane onto one side of a mesh; cylindrical wraps UVs around a tube-shaped object

Planar projection is best for flat surfaces like walls while cylindrical projection suits round objects like barrels or pillars with minimal seam artifacts.

What does 'texel density matching' across assets mean in a game environment?

Answer: Ensuring all objects in a scene use the same number of texture pixels per meter so no object looks sharper or blurrier than others

Matching texel density ensures visual consistency; an object with double the texel density will look unnaturally sharp next to its neighbors.

What is 'UV atlas' or 'texture atlas' packing used for?

Answer: Combining UVs from multiple separate objects into one shared texture map to reduce draw calls

Atlasing multiple meshes onto a shared texture reduces the number of unique materials and draw calls, improving render performance.

Why should UV islands have padding (also called 'gutter') between them?

Answer: To prevent texture bleeding between islands when mipmaps reduce texture resolution at a distance

Gutter space between UV islands prevents GPU mipmap filtering from blending texels across island borders, which would cause visible seam artifacts.

What is 'lightmap UV' and why does it need a separate UV channel?

Answer: A UV layout specifically designed for baked lighting with no overlapping islands, stored in a second UV channel

Lightmaps require unique (non-overlapping) UVs because overlapping islands would bake identical lighting onto different parts of the mesh incorrectly.

What does 'UV normalization' mean in the context of exporting assets?

Answer: Scaling UV islands so they fit within the standard 0–1 UV tile before export

UV normalization ensures all UV coordinates are scaled and positioned within the 0–1 range required by most real-time game engines.