Base colour (albedo) map

The base colour map (also called albedo, or diffuse in older workflows) is the texture that says what colour a surface is, with no light or shadow in it. Epic: "Base Color defines the overall color of the Material" (Unreal Engine documentation: Physically Based Materials in Unreal Engine). Marmoset defines albedo as "a color which describes the fractions of various colors of light that will scatter back out of a surface" (Marmoset: Basic Theory of Physically-Based Rendering).

#Why it matters

In physically based rendering, the shader adds all shading, highlights and shadows itself. So the base colour should look like a photo of the surface taken under perfectly flat, even light. Godot explains why it renamed its Diffuse slot to Albedo: in PBR "this color affects many more calculations than just the diffuse lighting path" (Godot documentation: Standard Material 3D and ORM Material 3D).

It also has two meanings, switched by the metallic map:

• On non-metal pixels it is the diffuse colour.
• On metal pixels it is the colour of the reflection. Metals have no diffuse colour, so this is where gold gets its yellow (Marmoset: Basic Theory of Physically-Based Rendering).

#Safe value ranges

Adobe's PBR Guide gives the most quoted rules, in 8-bit sRGB (Adobe Substance 3D: The PBR Guide – Part 2):

• Non-metals, dark end: "you should not go under 30-50 sRGB", "more tolerant at 30 sRGB and stricter at 50 sRGB".
• Non-metals, bright end: no values "higher than 240 sRGB".
• Raw metals: a reflectance of 70–100%, which Adobe maps to 180–255 sRGB, ideally from measured data.

Epic publishes measured base colours: charcoal 0.02, fresh asphalt 0.02, worn asphalt 0.08, bare soil 0.13, green grass 0.21, desert sand 0.36, fresh concrete 0.51, ocean ice 0.56 and fresh snow 0.81; and metals such as iron (0.560, 0.570, 0.580), silver (0.972, 0.960, 0.915) and gold (1.000, 0.766, 0.336) (Unreal Engine documentation: Physically Based Materials in Unreal Engine). The free Physically Based database collects similar values for many more materials, with a switch between sRGB and linear display (physicallybased.info: Physically Based: a database of physically…).

The two sources line up: the darkest real material sits inside Adobe's 30–50 tolerance, and fresh snow stays under 240.

#Colour space and storage

Base colour is the one main PBR map stored in sRGB. glTF requires it (Khronos Group: glTF 2.0 Specification), and Unity tells you to enable sRGB "for non-HDR color textures such as albedo" (Unity Manual: Default texture import settings reference). Its alpha channel, when present, is linear (Khronos Group: glTF 2.0 Specification) and is often used for opacity; Unity URP can also read smoothness from the base map's alpha (Unity Manual: Lit shader material Inspector window…).

#Example

#Common mistakes

• Too dark or too bright. Pure black (0) or pure white (255) breaks energy balance and looks fake in any lighting (Adobe Substance 3D: The PBR Guide – Part 2).
• Dark metals. A metal pixel with a dark base colour reads as black plastic; keep raw metal at about 180–255 (Adobe Substance 3D: The PBR Guide – Part 2).
• Saturated colours pushed to 100%. Real paint and dye rarely sit at the edge of the colour space. Check saturation as well as brightness.
• Imported as linear. The texture looks washed out and too bright in the engine. Check the sRGB flag (Unity Manual: Default texture import settings reference).
• Different value ranges across assets. One artist's "white" plaster at 250, another's at 200, and the scene looks patchy. Agree a reference chart in the art bibles and style guides.

#In different tools

• Unreal Engine: Base Color input, RGB clamped 0–1 (Unreal Engine documentation: Physically Based Materials in Unreal Engine). Use the Default compression setting with sRGB on.
• Unity: Base Map in URP and HDRP Lit, sRGB (Color Texture) enabled (Unity Manual: Default texture import settings reference).
• Godot: Albedo; colour and texture are multiplied together (Godot documentation: Standard Material 3D and ORM Material 3D).

#Related terms

physically based rendering · texture maps explained · metallic map · roughness map · ambient occlusion · colour for environments · value

#Further reading and watching