Blender Cycles Material Settings: Displacement, Emission, and Volumes

What will you learn in this guide?

Blender Cycles material settings cover a range of topics, from how much surface detail is reflected in the geometry to whether emissive materials are included in sampling and how volumes are calculated. Two methods aimed at the same appearance may differ in memory use or shadow accuracy. So rather than choosing settings by name alone, consider how they relate to the needs of your scene.

This guide walks through the differences between displacement and bump, when emission options take effect, and how to evaluate volume settings. The explanations are based on the material settings guide in the Blender Manual; they do not prescribe a universal “best” value for every option.

Requirements and setup

• Software: You need an installation of Blender that can run Cycles. The source page says material settings are available via Material > Settings or Shader Editor > Sidebar > Settings.

• Version: The source is the Blender Manual’s “latest” material settings page; it does not require a specific Blender version. If option names or locations differ in your version, consult that version’s manual.

• Account and license: The sources do not provide account requirements or pricing information for these settings.

• Test scene: Prepare a material to edit and a scene you can render to review changes. You’ll need a volume object or smoke simulation grid to evaluate volume options.

When comparing settings, keep the scene conditions as consistent as possible. This makes it easier to identify how a change affects the surface, shadows, or volume. This is not a technical requirement stated in the manual, but a suggested workflow for evaluating options more consistently.

Step-by-step surface and emission settings

1. Decide whether surface detail needs to change the geometry

There are three approaches to choosing a displacement method. Displacement Only changes the surface shape in the mesh. The source manual notes that this method can deliver the best quality when the mesh has enough subdivisions, but it also requires more memory. Test it when the outline or physical shape of a surface viewed up close matters. Factor in the model’s geometric density and the scene’s memory use as well.

Bump Only affects the surface normal used for shading rather than changing the actual geometry. Since it leaves the geometry untouched, it uses less memory than displacement, but only approximates the appearance. It does not actually change the silhouette, and bump-based displacement detail does not cast shadows onto itself. This makes it worth testing for fine surface textures where silhouette changes are not expected; it may not be sufficient on its own where the outer contour needs to change.

Displacement and Bump combines both methods in the same material. Displacement is used on a coarser mesh, while bump adds the appearance of finer details. Try this combination when both the overall surface shape and small-scale details matter. Don’t judge the result only in a close-up; also check it from the camera distance used in the architectural presentation.

2. Choose emission sampling based on the material’s light source

Emission Sampling is relevant when the material has an emission node. Without one, this setting has no effect. For emissive surfaces, None means the surface is not treated as a light source during sampling. With Auto, whether the surface is treated as a light source is determined by its emission strength.

Other options let you choose which side of the surface contributes light. Front considers only the front side; the manual also describes it as a useful choice for closed meshes whose interior is not visible. Back considers the back side, while Front and Back includes both sides in sampling. If you’re using closed geometry or a directional emissive surface, compare the options in your scene. The source does not recommend a single choice for every situation.

3. Check transparent shadows and bump-related artifacts

If the material contains a Transparent BSDF, check how the Transparent Shadows option affects shadows. Turning it off may speed up rendering, but can compromise shadow accuracy. If shadows cast by transparent materials matter in your scene, don’t judge the setting by speed alone.

Bump Map Correction is designed to correct shadow terminator artifacts that can be caused by bump mapping. Consider enabling it if shadows behave unexpectedly on surfaces using bump. As you inspect the result, look at both the illuminated appearance of the surface and the shadow transitions.

Evaluate volume settings according to scene conditions

4. Match the sampling method to the light’s position relative to the volume

Volume sampling includes Distance, Equiangular, and Multiple Importance. For a dense volume illuminated from a distance, try Distance; the manual notes that this method is generally more efficient in those conditions. If the light is inside or near the volume, Equiangular is a better starting point. If both lighting conditions are present, consider Multiple Importance.

These are suggestions based on scene conditions; they do not guarantee the same result in every project. If you’re using fog or a similar volume in an architectural interior, first identify where the lights are relative to the volume. Then try the method that seems appropriate and check the visual difference.

5. Check the Interpolation and Step Rate options

The interpolation method also affects the result for volume objects and smoke simulation grids. Linear is a simpler option that may suit thin volumes. Cubic can produce a smoother, higher-quality result in denser volumes, but it is slower. Decide based on the volume’s density and appearance in the scene.

Step Rate sets the distance between samples taken by the volume shader. If procedural textures add detail that isn’t sufficiently visible at the default sampling interval, consider reducing the distance between samples. This option is available only when Render > Volumes > Biased is enabled. So if the setting is missing or unavailable, check that condition first; the source manual does not specify any other prerequisites.

Common mistakes

• Treating bump as geometric relief: Bump affects the surface normal used in shading; it does not change the surface outline. If the silhouette needs to change, consider displacement.

• Ignoring the cost of displacement: It can use more memory, and the mesh needs to be finely subdivided to get good results.

• Assuming emission settings affect every material: Emission Sampling has no effect if there is no emission node.

• Choosing volume sampling independently of the lighting: The distance between the light and the volume affects which options are suitable.

• Overlooking shadow accuracy in pursuit of speed: Turning off transparent shadows may speed up rendering, but can produce inaccurate shadows.

Next steps for architectural and archviz workflows

In architectural visualization, displacement can be considered for materials where the actual surface shape matters, while bump can add the appearance of surface detail without changing the geometry. In interior scenes with emissive surfaces, transparent materials, or volume effects, review the relevant sampling settings as well.

Before applying an option across the whole scene, test it on a representative material from the camera angle you plan to use. For displacement, consider memory use and mesh density; for transparent shadows, accuracy; and for volumes, light placement, interpolation, and render speed. The source does not specify hardware requirements or render times. Hardware compatibility and performance decisions should therefore be based on the setup being used and the actual project scene.

Source and license

This guide has been translated and adapted from the Material Settings page in the Blender Manual. The source is published under the CC BY-SA 4.0 license.