Standard Shader (Specular workflow)

Unity's Standard Shader (Specular setup) uses Albedo and Specular/Smoothness maps, combining them to create some of the material's aspect – mainly its color and reflectance qualities. The following shows the difference between the Albedo and Smoothness maps:

• Albedo: This is the material's diffused color. Plainly and simply, this is how you usually describe the appearance of the Material (the British flag is red, white and blue; Ferrari's logo is a black horse in a yellow setting; some sunglasses' lenses are semi-transparent gradients). This description, however, can be deceptive. Purely metallic objects (such as aluminum, chrome, and gold) should have black as their diffuse color. Their colors, as we perceive them, have originated from their specular channel. Non-metallic objects (plastic, wood, and even painted or rusted metal), on the other hand, have very distinct diffuse colors. Texture Maps for the Albedo property feature RGB channels for colors and (optionally) an Alpha Channel for transparency.
• Specular/Smoothness: This refers to the shininess of the material. Texture maps make use of RGB channels for specular color (which inform hue and intensity), and Alpha Channel for smoothness/gloss (dark values for less shiny surfaces and blurred reflections; light/white values for shiny, mirror-like appearance). It is important to note that non-metallic objects feature neutral, very dark specular colors (with plastic, for instance, you should work with a grey value around 59). Metallic objects, on the other hand, feature very light values, and are also a bit yellowish in hue.

To illustrate such concepts, we have created a battery object, featuring brushed metal caps and a plastic body. Observe how each map contributes to the final result: