Physically Based Rendering – For Next-Generation game graphics

In this blog we will explore the fundamentals of Physically Based Rendering (PBR) and its growing influence in the world of 3D graphics. Now, let’s delve deeper into the technical aspects of PBR, examining the underlying concepts and their practical implementation.

The Science Behind the Screen

PBR relies on the BRDF (Bidirectional Reflectance Distribution Function) – a fancy term for a mathematical equation that describes how light scatters over a surface. By incorporating real-world material properties like roughness, metalness, and normals into the BRDF, PBR accurately simulates light transport.

Popular PBR models include:

Cook-Torrance: A physically-based and microfacet-based BRDF model, good for representing metallic and dielectric surfaces.

Ward: Another microfacet model known for its efficiency and focus on rendering speed.

Lambert: A simpler model ideal for diffuse surfaces with uniform reflectance in all directions.

Bringing the Math to Life: Shaders and Material Properties

The magic of PBR happens at the shader level. Shaders are programs written in languages like GLSL or HLSL that define how objects are rendered on the screen. PBR shaders utilize BRDF models and material properties to calculate lighting effects for each pixel.

Here are some key PBR material properties:

Base Color: The inherent color of the material.

Roughness: Controls the microscopic surface irregularities, affecting how 

light scatters. A smooth surface (low roughness) produces sharp reflections, while a rough surface (high roughness) scatters light more diffusely.

Metalness: Defines how metallic a material is. Metals have high metalness values, resulting in strong specular reflections. Dielectric materials (like plastic) have lower values and exhibit softer reflections.

Normal Map: A texture that encodes surface details like bumps and grooves, influencing how light interacts with the object.

Advanced PBR Concepts

PBR offers a rich ecosystem for exploring advanced lighting effects:

Ambient Occlusion: Simulates shadows in surface cavities where light struggles to reach.

Subsurface Scattering (SSS): Captures how light penetrates translucent materials, creating a soft, glowing effect.

Anisotropy: Models materials with a preferential direction of roughness, like brushed metal.

The Art of PBR: Balancing Efficiency and Accuracy

While PBR offers incredible realism, it can be computationally expensive for complex scenes. Artists need to strike a balance between accuracy and performance. 

The Future of PBR: Continuous Innovation

The field of PBR is constantly evolving. Researchers are exploring new BRDF models, advanced light transport algorithms, and improved material representation for even more photorealistic visuals.

This technical breakdown equips you with a deeper understanding of PBR’s inner workings. With continued exploration and innovation, PBR promises to revolutionize how we create and experience 3D worlds.