Physicalbased

Physicalbased is a term used to describe physically based rendering and shading workflows in computer graphics. These approaches aim to reproduce plausible light-material interactions based on real-world physics, producing materials that look consistent under varying lighting conditions. Key principles include energy conservation, physically plausible reflectance, and parameterized material properties that map to real surface characteristics.

Core concepts include the microfacet BRDF, typically modeled with distributions such as GGX, which describe how microfacets on a rough surface reflect light; the Fresnel effect, where reflectivity increases at grazing angles; and material parameters such as base color (albedo), metallic, roughness, and normal maps. The metallic/roughness workflow is the most common, where metals use colored specular reflection and non-metals rely on diffuse base color with a separate metallic flag. Textures like ambient occlusion, roughness, metallic, and normal maps are often combined to define a material’s appearance. Real-time engines also use environment-based lighting, through HDRI maps or image-based lighting, to illuminate scenes physically.

Implementation context: PBR is widely adopted in modern game engines (Unity, Unreal, Godot) and content-creation tools (Blender, Substance). It supports both real-time rendering and offline rendering, with different shader implementations but similar physical principles. Key goals include consistent metalness and roughness across lighting environments and plausible Fresnel behavior.

Limitations and scope: While PBR improves realism and consistency, it is a simplified model of light transport. It may not capture all materials accurately, especially translucent or subsurface scattering materials like skin or marble, and achieving true physical accuracy requires accurate lighting measurements and materials. Artists may still adjust parameters for artistic intent.