In this lesson, you will learn how to configure your PBR material properties to accurately distinguish between conductive metals and dielectric insulators.
In the Physically Based Rendering (PBR) workflow, we describe surfaces based on how they interact with light. To achieve realistic results, we categorize materials into two main buckets: conductors (metals) and dielectrics (non-metals/insulators).
The Metallic Workflow
The Metallic slider in Unity’s Standard or URP/HDRP Lit shaders determines the "metalness" of a surface. When you set this value to 1.0, the shader treats the material as a pure metal. Metals reflect almost all light and have no diffuse (albedo) color; instead, the surface color is derived entirely from their specular reflections.
Conversely, setting Metallic to 0.0 treats the material as a dielectric. Dielectrics reflect very little light as specular highlights, and their color is primarily defined by the Albedo map. In practice, most surfaces are strictly one or the other. Avoid "half-metallic" values unless you are dealing with very specific edge cases like dust or oxidized metals.
The Roughness (Smoothness) Workflow
The Smoothness (or Roughness) parameter controls the microscopic detail of the surface.
- Low Smoothness (High Roughness): Light hits the surface and scatters in many directions, creating broad, dull specular highlights. Think of concrete or matte plastic.
- High Smoothness (Low Roughness): The surface is polished, causing light to reflect in a precise, unified direction, resulting in sharp, mirror-like highlights.
Implementation Tip
When authoring your maps, use the Metallic property to define the type of material and the Smoothness property to define the finish of the material. For example, a gold ring would have a Metallic value of 1.0 and a high Smoothness, while a weathered wooden table would have a Metallic value of 0.0 and a very low Smoothness. You can use a Mask Map or a MetallicSmoothness texture to drive these values per-pixel, allowing a single object to have both metallic bolts and non-metallic paint.
Key Takeaway: Use the Metallic property to define the physical nature of the material (conductor vs. dielectric), and use Smoothness to define the microscopic finish of the surface.