The Unity URP PBR material workflow is metalness-roughness, but Unity names one slot Smoothness, not Roughness. That single difference causes most “my Locker3d map looks wet” tickets. This guide covers URP Lit map slots, Texture Importer flags, packing, and resolution choices for mobile versus PC.

Create a URP Lit material

Confirm the project is Universal Render Pipeline (Window → Rendering → Render Pipeline Converter if you migrated). Create a Material and set Shader to Universal Render Pipeline / Lit. Workflow Mode should be Metallic. Surface Type Opaque for wood, concrete, and painted metal. Assign the albedo to Base Map. Assign the normal to Normal Map and keep the default bump scale until you compare against a real reference. If you downloaded maps from the Locker3d free CC0 library, you already have the files this shader expects—you only need to convert roughness to smoothness.

Map slots and the smoothness trap

URP Lit uses:

  • Base Map: albedo color, plus optional alpha for cutoff or transparency.
  • Metallic: a grayscale metallic map, or a slider if the surface is a single value.
  • Smoothness: often stored in the metallic map’s alpha, or a slider. Smoothness = 1 − roughness.
  • Normal Map: tangent-space, typically OpenGL-style in Unity (green up). Flip the green channel if the pack is DirectX.
  • Occlusion: AO, linear, multiplied in the shader.
  • Height Map: optional parallax on the Lit shader; use sparingly on mobile.

If your pack ships roughness (Locker3d and most CC0 sets do), invert it in an image editor and save a smoothness PNG, or invert in a Shader Graph. Do not plug roughness into Smoothness and hope. For map definitions, see the PBR textures complete guide.

Texture Importer color space

Select each texture. Albedo: sRGB on (Texture Type Default). Normal: Texture Type Normal map; Unity will convert from a height or from a regular RGB normal. Roughness, smoothness, metallic, AO: sRGB off (uncheck sRGB). Compression: Normal quality BC7 or DXT for PC; ASTC for mobile. Generate Mip Maps on. Wrap Mode Repeat for tileable floors; Clamp for unique UV islands. Filter Mode Bilinear is fine; Trilinear if you see mip shimmer on a large wood floor. If you previewed the same set in Blender, compare against the Blender node setup—color space rules match, slot names do not.

Shader Graph and packing

For production, pack metallic in R and smoothness in A of one texture so URP Lit can sample once. AO can live in another channel if you write a Shader Graph. Keep a source folder with the original roughness so you can re-pack later. Expose tiling and offset as material properties; artists should not duplicate materials just to change scale. Use Material Variants or presets for wet/dry concrete by multiplying smoothness, not by authoring a second 4K albedo. Browse concrete and metal when you need extra variants without leaving CC0.

1K vs 2K vs 4K in URP

Mobile URP: prefer 1K, ASTC, and fewer unique materials. Standalone PC: 2K is the default for characters and rooms. 4K is for a kitchen counter hero or a marketing still, not for every wall. Unity’s Max Size lets you keep 4K in the project and ship 2K. Watch the Memory Profiler; four 4K maps at BC7 are not free even on a 3080. Locker3d textures can go into commercial Unity games under CC0—details in CC0 textures explained. New to PBR? Use the beginner guide and the rest of the blog.

Frequently asked questions

Which Unity shader should I use for PBR textures in URP?

Use the URP Lit shader for opaque metalness-roughness materials. Assign Base Map, Metallic/Smoothness, and Normal Map, then match import sRGB settings to each map type.

Why is my URP material too shiny or too dark?

Smoothness is the inverse of roughness. If you plug a roughness map into Smoothness without converting it, the surface looks wrong. Also disable sRGB on data maps.

What texture size should I use in Unity URP?

Use 1K for mobile and tiny props, 2K for most PC/console assets, and 4K only for hero close-ups. Set Max Size on the importer so source files can stay larger.