What is a roughness map?
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Discuss your projectWhat is a roughness map?
Definition of Roughness Map
A roughness map is a grayscale texture that controls surface roughness in physically based rendering (PBR). It affects the sharpness and spread of reflections without changing the model’s shape. Our projects for Kvadrat and Schramm show how material rendering and a brand’s visual language work together.
- Black / low values → smooth, reflective areas
- White / high values → wider, more subdued reflections
Roughness is not the same as reflectance. The type of sheen, the color of the reflection, and the intensity depend on the material model and other parameters. Therefore, check the texture within the complete material under the intended lighting conditions.
Examples of Roughness Maps
Dark values typically indicate lower roughness, while light values indicate higher roughness. The following grayscale textures show possible distributions. Whether a material looks convincing also depends on the scale, lighting, and the other material channels.
Bouclé fabric
Light and dark areas follow the fabric structure. As a roughness texture, they control local variations in sheen. Loops and knots need additional geometry or suitable surface maps to describe their three-dimensional form.
Varnished wood
The predominantly dark texture contains subtle lighter streaks. In the Roughness channel, these can represent duller scratches on a smoother painted surface.
Fine Linen
The fine fabric texture is characterized by subtle variations in gray scale. Its effect must be evaluated in conjunction with the fabric material and the lighting.
From Technical Term to Visual Experience
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View WorkHow Roughness Works in the PBR Shader
| Gray value | Microscopic surface | Visual effect |
|---|---|---|
| 0 – 0.25 | low modeled roughness | Clear reflections, harsh highlights |
| 0.25 – 0.5 | moderate to low roughness | soft highlights, slight blur |
| 0.5 – 0.75 | medium to high roughness | broader, less sharp reflections |
| 0.75 – 1 | high modeled roughness | widely scattered reflections |
Note: The table shows qualitative trends, not fixed measurements for specific materials. Roughness does not alter the base color or geometry. To create actual height differences, you need geometry or a displacement map.
Typical workflow: Roughness in 5 steps
1. Check the UV setup
Without a clean UV layout (→ UV mapping), you risk stretching and harsh transitions in the roughness.
2. Capture material details
Differences in roughness can be derived from material references and painted as textures or generated procedurally. A high-poly model isn't always necessary for this. Adobe's PBR guide explains how the material channels work together.
3. Bake roughness
In texture baking , predefined material information can be applied to textures. Geometry alone does not provide measured roughness. Baked masks can help in creating a roughness texture.
4. Tonal adjustments and gamma
Roughness contains non-color data and is imported without sRGB color correction. The Albedo / Base Color Map , on the other hand, contains color information. Use the settings expected by the target system.
5. QA & brand look
Compare the material with its references in the target renderer. In Three.js, the roughness value and roughness texture both affect the result. Also assess the lighting, environment, and viewing angle.
Quick Tips from Real-World Experience
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Metal vs. dielectric Metals combine roughness with a metalness map; plastic and wood use Metallic = 0.
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Describe Scratches in Detail A normal map can alter the lighting of a depression. A roughness mask controls its sheen. Combine the two only if it fits the material reference.
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Plan texture resolution Choose it for the framing, camera distance, and level of detail required. More pixels cannot correct insufficient bit depth or an incorrect color space setting.
Comparison: Roughness vs. Glossiness
| Parameters | Value range | Inverted? | Popular Engines |
|---|---|---|---|
| Roughness | 0 (smooth) to 1 (rough) | no | e.g., Unreal Engine, Blender, and Three.js |
| Glossiness | 0 (rough) to 1 (smooth) | often 1 minus roughness | e.g., shaders with glossiness or smoothness |
Tip: With the appropriate definitions, roughness equals 1 minus glossiness. However, before converting, check the interpretation of the values and the shading model for both systems.
FAQ - Roughness Map
What exactly does a roughness map control?
It controls the microscopic roughness in the material model and, consequently, the width and sharpness of reflections. It does not alter the geometry. Low values produce a smoother appearance, while high values produce a more matte appearance; the result also depends on the light and other material parameters.
How do I use a roughness map in Adobe Dimension?
The Adobe Standard Material supports roughness as a value or a grayscale image. Black represents polished areas, while white represents matte areas. A glossiness texture must match the expected interpretation of the values; setting the glossiness to zero across the board is not a universal rule for this.
What should I keep in mind regarding roughness in 3ds Max?
In Physical Material, check whether roughness or the inverted glossiness interpretation is active. Setting up a material input correctly does not export a texture. The transferred data also depends on the export format and exporter.
Do I need special UV maps before baking?
For image-based textures, the UV mapping, scale, and transitions must be correct. When baking, individual surfaces usually require distinct UV regions. Plan your padding based on resolution and filtering; eight pixels is not a universal guideline.
Can I create roughness directly during texture baking?
Pre-calculated roughness values or procedural materials can be baked depending on the tool. However, a high-poly model alone does not contain any information about how rough its material is. Geometry maps and masks can support texture creation.
Why does my roughness look flatter in the Web Viewer than in the offline render?
Compare color space, roughness intensity, lighting environment, tone mapping, resolution, and texture filtering. In the current version of Three.js, roughnessMap is a non-color texture with NoColorSpace; the green channel provides the roughness values. The previous texture.encoding setting is no longer part of the current API.
Can I stack multiple detail roughness maps?
Yes, if the shader supports blending. Roughness requires a single value channel; its mapping depends on the target system. Additional detail textures may increase memory requirements and the number of texture accesses. Check the result in the material.
Are there "physically correct" roughness ranges?
There are no universal roughness ranges based solely on material class. Metal can be polished or rough, and plastic can be matte or glossy. Compare the material sample, surface treatment, and lighting; roughness is no substitute for this comparison.