Physically Based Rendering (PBR) has become a cornerstone of modern 3D rendering and game development. It enables artists to create realistic materials that accurately reflect light and react to various environmental conditions, making them virtually indistinguishable from real-world objects. But what exactly is PBR, and what types of textures are involved in creating these visually stunning results? In this comprehensive guide, we’ll delve into PBR materials, explore the different textures they use, and understand how these textures interact with lighting to produce photorealistic results.

1. What is PBR Material?
Physically Based Rendering (PBR) is a methodology in 3D graphics that aims to represent real-world materials in a realistic manner by accurately simulating the interactions between surfaces and light. Unlike traditional rendering techniques, PBR uses complex mathematical formulas to simulate how light behaves on various surfaces, ensuring that the material appears consistent under different lighting conditions.
PBR materials are often used in real-time engines like Unreal Engine, Unity, and modern 3D modeling software such as Blender3D. The core advantage of using PBR is that it allows for materials to appear more lifelike, especially when dealing with various lighting scenarios. As a result, it’s widely adopted in the film, gaming, and architectural visualization industries.
2. Importance of PBR in Modern 3D Rendering
PBR has transformed the way materials are created and used in 3D environments. One of its key benefits is that it simplifies the process of achieving photorealism. Once a PBR material is created, it looks consistent under different light intensities and angles, reducing the need to tweak material settings continuously.
This consistency also means that PBR materials can be reused across projects and different software platforms without any loss of visual fidelity. As a result, artists and developers can achieve higher productivity and visual quality.

3. The Core Textures in PBR
To create PBR materials, various textures are used to define the properties of the surface. Each texture has a specific role in defining how light interacts with the material.
3.1 Base Color/Albedo

The Base Color or Albedo texture defines the base color of the material without any shadows or highlights. It contains the surface color information and acts as a diffuse map in traditional shading models. This texture doesn’t store any lighting information, making it a “flat” representation of the surface color.
Example: For a brick wall material, the base color map would have the red and brown hues of the bricks and the gray of the cement, but it would not include the shading caused by the brick’s depth.
3.2 Metallic

The Metallic texture dictates whether the material is metallic or non-metallic (dielectric). It uses a grayscale map where white (value of 1) represents a fully metallic surface, and black (value of 0) represents a non-metallic or dielectric surface. Metals reflect light differently than non-metals, making this texture crucial for achieving realistic reflections and highlights.
Example: A steel surface would have a metallic map value of 1, while a wooden surface would have a metallic value of 0.
3.3 Roughness

The Roughness texture controls the micro-roughness of a material’s surface. It defines how smooth or rough a surface appears by determining the diffusion of light. A smooth surface reflects light in a sharp, specular manner, while a rough surface scatters light in various directions, resulting in a more diffused and matte look.
Example: For a glossy car paint, the roughness value would be low (dark in color), while for a concrete surface, the roughness value would be high (light in color).

3.4 Normal Map

A Normal Map is used to simulate small surface details like bumps, grooves, and scratches without altering the actual geometry of the object. This texture uses RGB information to encode surface orientation, providing the illusion of complex surface detail without the computational cost of adding extra polygons.
Example: The rough surface of an orange peel or the grainy texture of sandpaper can be represented using a normal map.

3.5 Height/Displacement

Height or Displacement maps provide actual depth information by altering the geometry of the surface. Unlike normal maps that only simulate details, displacement maps physically move vertices, creating actual protrusions and indentations on the surface.
Example: The uneven surface of cobblestones or the depth of grooves in wood can be achieved using a displacement map.
4. Additional Textures in PBR
In addition to the core textures, other maps can be used to add more complexity and detail to a material.
4.1 Ambient Occlusion

Ambient Occlusion (AO) simulates the self-shadowing effect that occurs in crevices or where objects meet. It adds depth and realism by darkening areas that receive less ambient light.
4.2 Specular Map

The Specular Map controls the shininess and color of specular highlights. It’s mostly used in the specular workflow of PBR to define how reflective a surface is.
4.3 Emissive Map

The Emissive Map controls the parts of the material that emit light. This is used to create glowing effects, such as LED lights on a panel or a glowing lava surface.
4.4 Opacity Map

The Opacity Map defines the transparency of the material. It uses a grayscale map where black (0) is fully transparent, and white (1) is fully opaque.
4.5 Subsurface Scattering

Subsurface Scattering (SSS) simulates the way light penetrates translucent materials like skin or wax. It’s commonly used for organic materials to create a soft glow.
5. PBR Workflow: Specular vs. Metallic
PBR can be implemented using two main workflows: Specular/Glossiness and Metallic/Roughness. Each workflow has its advantages, and the choice depends on the project’s needs:
- Metallic/Roughness Workflow: This is the standard workflow used in most engines, focusing on a simplified representation of metal and non-metal properties.
- Specular/Glossiness Workflow: This workflow provides more control over reflective properties by using a specular map to define the color and intensity of reflections.
6. How PBR Textures Interact with Lighting
PBR materials interact with light based on their textures. For example, a metallic material will reflect light differently than a dielectric (non-metallic) material. The roughness value will control how blurred or sharp the reflection is, and the normal map will add extra surface details to influence how light bounces off the surface.
Understanding this interplay is crucial for creating realistic materials that react naturally to lighting changes in different scenes.

7. Real-world Use Cases of PBR Materials
- Game Development: PBR is widely used to create realistic game environments and characters that look consistent in various lighting conditions.
- Architectural Visualization: PBR helps visualize materials like wood, concrete, and glass with high realism, aiding in better project presentations.
- Film Production: PBR materials enable the creation of photorealistic CGI that seamlessly blends with live-action footage.
8. Tools and Software for Creating PBR Textures
Various software tools are available for creating and editing PBR textures:
- Substance Painter: A dedicated texturing tool for creating PBR materials.
- Quixel Mixer: Allows creating PBR textures using a library of scans.
- Blender: An all-in-one tool that supports PBR material creation and rendering.
Conclusion

Physically Based Rendering (PBR) has revolutionized the world of 3D graphics by providing a standardized method to create highly realistic materials. Understanding the core and additional textures involved in PBR allows artists to craft materials that can react to any lighting scenario, adding to their visual fidelity and realism. Whether you’re a game developer, film artist, or designer, mastering PBR materials and their textures is a valuable skill that can elevate your work to new heights.
References
Unity Documentation: Physically Based Rendering in Unity
“Physically Based Rendering: From Theory to Implementation” by Matt Pharr, Wenzel Jakob, and Greg Humphreys
Blender Documentation: PBR Materials in Blender
Unreal Engine Documentation: Using PBR Materials in Unreal Engine
Substance Painter Official Website: What is PBR?