What guidelines apply to the 3D models' textures?

• They must be JPEGs (exception is .png materials with alpha channel representing elements such as railings, windows, grates, stair cases, etc..).
• They must never exhibit Z-fighting.
• They must be sized in powers of two, preferably 1024 x 1024 (max resolution:2048 x 2048).
• They must have accurate and non-repeating images for street-side faces.