UV Unwrapping

Unwrapping the mesh allows Blender to assign a 2D texture to an otherwise 3D object. It flattens out the faces and makes it easier to achieve the desired texturing results.

Image textures in Blender are usually in a 1:1 ratio (e.g: 1024x1024), but using power-of-2 for texture maps is also fine (e.g: 1024x512 or 4096x1024 etc).

Please Note

It is advised to stay away from image maps of dimensions that are not 1:1 or power-of-2, as they will negatively affect performance.

General guidelines for texture sizes:

• Large objects that need high quality textures (e.g: floors, walls, roof, landscapes etc.): 4096x4096 for desktop and 2048x2048 for mobile
• Medium sized objects that need to appear in decent quality when being viewed as a part of the environment (e.g: furniture etc): 1024x1024 for desktop and mobile
• Small objects: Recommended to use colors from the 8x8 color palette seen here, but if an image texture is required, then use 512x512 for both desktop and mobile
• Faces that require more detail should take up more space in the UV map than faces of a single color.

To unwrap an object in Blender go into Edit mode, select the faces you want to unwrap and then click UV > unwrap in the menu bar (or use shortcut U).