AI texture painting: how PBR channels work in Marble Voyage

PBR stands for physically based rendering, and it describes a way of defining surface materials that behaves consistently under different lighting conditions. If you have ever wondered why a material looks right in one scene and wrong in another, the answer is usually in the PBR channels. Here is what each one does and how to control it through the Marble Voyage texture interface.

Albedo: the base colour ¶

The albedo map defines the base colour of the surface with no lighting information baked in. A common mistake is to describe a material as 'dark' and expect the albedo to be dark. In PBR, darkness comes from lighting, not from the albedo. The albedo for a black rubber surface is a dark grey, not pure black, because pure black absorbs all light and produces an unrealistic result.

When you describe a texture in Marble Voyage, colour terms go into the albedo. 'Terracotta orange', 'aged brass', 'matte white ceramic' all drive the albedo generation. If the colour is not what you expected, try being more specific: 'warm ochre with brown undertones' is more useful than 'orange'.

Roughness and metallic: the surface behaviour channels ¶

The roughness map controls how diffuse or specular the surface is. A roughness value of 0 is a perfect mirror. A value of 1 is completely matte. Most real-world surfaces sit between 0.3 and 0.8. You can adjust roughness through the chat interface by saying 'make the surface more matte' or 'add a slight sheen to the fabric'.

The metallic map is a binary switch in most PBR workflows: a value of 1 means the surface is a conductor (metal), and a value of 0 means it is a dielectric (everything else). Mixed values are used for surfaces like carbon fibre or painted metal where the material is partially conductive. The agent handles this automatically when you describe materials like 'brushed aluminium' or 'lacquered wood'.

Emissive maps for glowing surfaces ¶

The emissive map adds light emission to a surface independent of scene lighting. It is used for screens, neon signs, glowing runes, LED strips, and any surface that appears to produce its own light. In Marble Voyage, describe the emissive region explicitly: 'the panel on the chest glows blue' or 'the circuit traces emit green light'.

Emissive intensity is controlled separately from the emissive colour. If the glow looks too subtle in your target engine, increase the emissive multiplier in Unity's material inspector or Unreal's material editor rather than regenerating the texture.

PBR materials reward specificity. The more precisely you describe the surface, the less time you spend in the chat interface correcting the result.