Physically based rendering (PBR) is a way to shade 3D surfaces so they respond to light like real materials. Instead of painting a final look into one texture, you feed the renderer measurable properties. The same wood plank then looks correct under a cloudy HDRI, a hard sun, or a studio rig—and in more than one engine.

The physics PBR actually approximates

PBR does not simulate every photon. It approximates a few rules that matter on camera. Energy conservation says a surface cannot reflect more light than it receives. Microfacet theory treats a “smooth” surface as tiny mirrors; roughness is how chaotic those mirrors are. Fresnel says reflections grow stronger at grazing angles, which is why a matte floor still flashes at the horizon. Metals and dielectrics split: metals tint their mirror reflection and have almost no diffuse color; dielectrics have colored diffuse and a weak greyscale specular. PBR textures are just image files that feed those rules.

Energy conservation and Fresnel in practice

If you crank specular and keep a bright diffuse, older shaders can look wet and glowing. A PBR shader darkens the diffuse as specularity rises so the sum stays plausible. You do not usually paint Fresnel by hand; the BRDF applies it. Your job is to keep albedo in a realistic range (avoid 0 or 255), keep roughness meaningful, and avoid mid-grey metalness. Those three habits prevent most “plastic wood” and “chalk metal” failures.

The maps that drive a PBR material

  • Albedo / base color — surface color with no lighting baked in (sRGB).
  • Roughness — blur of reflections; non-color data.
  • Metalness — 0 dielectric, 1 metal; non-color.
  • Normal — tangent-space detail; non-color, through a Normal Map node.

Height, AO, and opacity are extras. You can start with a dielectric from wood or concrete and only add metalness when you pull metal.

Metalness versus dielectric behavior

Paint, plaster, fabric, and stone are dielectrics: metalness stays at 0, color lives in albedo, and roughness does most of the styling (polished tile versus raw timber). Raw steel, copper, and gold flip metalness to 1 and move their color into the reflection. Rust and dust are dielectrics sitting on metal, so those pixels go back to 0 and pick up brown albedo. That binary split is why metalness packs stay small and predictable.

Why the same texture works across engines

Blender Principled BSDF, Unreal’s default lit material, and Unity URP/HDRP all implement a similar metalness-roughness BRDF. A CC0 set from Locker3d therefore ports with mainly color-space and normal-Y checks. That is the practical promise of PBR: one library, many renderers. Offline engines such as V-Ray and Corona can ingest the same maps, sometimes through a specular-gloss wrapper.

How to start using PBR today

Download a complete pack, set albedo to sRGB and data maps to non-color, and connect them to a Principled-style shader. Light with an HDRI so roughness has something to reflect. Step-by-step wiring is in how to apply PBR textures in Blender. New users can follow PBR textures for beginners. Locker3d files are CC0—commercial use, no attribution required. More guides: blog.

Frequently asked questions

Is PBR only for photoreal games and archviz?

No. PBR is a lighting model. You can still author stylized albedo and roughness. The gain is that materials stay consistent when you change lights or move the asset between Blender, Unreal, and Unity.

What maps do I need for a basic PBR material?

Albedo, roughness, and a normal map cover most dielectrics. Add metalness for raw metal. Ambient occlusion and height are optional extras, not the core model.

Are Locker3d textures built for PBR?

Yes. Locker3d CC0 packs use albedo-style color with roughness, normal, and metalness where the surface needs them. You can use them in commercial projects without attribution.