PBR texture maps mimic real-life materials with a high degree of accuracy. Indeed, the rendering of PBR texture maps is guided by rules of physics. Key benefit of PBR maps technology is their versatility across rendering programs and game engines. Technology maintains the material pipeline.
Types of materials:
There are two main types of materials: dielectrics and metals. Here’s how they each interact with light:
Dielectrics:
What they do: Dielectrics let light in, scatter it around inside, absorb some, and then send some back out.
Result: This gives them a soft, white glow.
Metals:
What they do: Metals don’t let light through; instead, they reflect it, sometimes completely.
Result: This reflection creates a shiny, colored shine, unlike the softer glow of dielectrics.
Material parameters (PBR texture maps):
Diffuse / Albedo map is a base image showing strength and color of diffuse reflections. It’s just the color or base material texture without shadows or shine. Metals don’t reflect this way, so their color is black.
Specular map demonstrates the shininess of a material. The Physically-Based Rendering (PBR) texture map displays solely the illumination the object receives, excluding any reflection from the environment. It contains black and white pixels, where lighter pixels reflect light more effectively and produce glare more readily. Consequently, darker pixels have matt materials that reflect light less effectively.
Metalness map shows whether a material is metal or not. Often, a simple black-and-white texture map is used to indicate which areas of the object are non-metallic (black color) and which are metallic (white color). An alternative method is to specify a numerical value, such as 0 for dielectric, 1 for metal.
Ambient Occlusion map is used to add subtle shading and shadows to the model. In this grayscale image, white areas represent fully lit portions of the model, while black areas indicate fully shaded regions.
Refraction map is a variant of opacity PRB texture map. It shows the change in the direction of light that occurs at the interface between two environments through which the light passes. Most refraction maps have constant values.
Roughness map shows how bumpy or smooth a material is. Rough surfaces make light scatter widely, creating softer reflections compared to smooth surfaces. Roughness values range from 0.0 to 1.0. A value of 0.0 means sharp reflections with no light scattering. In 1.0 roughness, reflections become fuzzy.
Opacity / Alpha / Transparency map shows how transparent an object is. It helps to create transparent objects (glass, water), or it can make visible or not visible parts of objects (grid, leaf). In the second case, a black-and-white image indicates which parts to display and which not.
Self-illumination map allows materials to emit their own light, enabling them to be visible in dark areas.