--- title: "Smoke Color" canonical: "https://documentation.chaos.com/space/VC4D/116853677/Smoke%20Color" format: markdown --- This page provides general information about the Smoke Color sub-section of the Rendering tab of the V-Ray Volumetric Grid. ## **Overview** --- This roll-out controls the Diffuse color of the Volumetric Shader. The Smoke Color can be a uniform color, a mixture of colors dragged by the simulation (RGB), a function of any physical channel, or sampled from a texture. It is also affected by lights and shadows cast by objects in the scene. > Macro (ui-text-box) > > The diffuse color needs external light to become visible if GI is enabled in the V-Ray Render Settings in Cinema 4D. ## **Parameters** --- **Scattering** – Controls how the light rays are scattered inside the volume. **Ray-traced (GI only)** – Enables physically accurate scattering of light rays. This mode produces the most realistic results but is the slowest to render. It requires V-Ray with enabled Global Illumination; otherwise, the rendered result would be the same as if the option is **Disabled. **The **Master Multiplier** does not affect the rendering in this mode. **Disabled** – Disables scattering. The **Master Multiplier** value can be used to correct the brightness because, without light scattering, the volume would generally render darker. **Approximate** – Uses an approximate formula that is faster than** Ray-Traced** scattering and produces good-looking results. Brighter areas of the volume would transfer light farther than dark areas. This option is not supported by the **Volumetric Geometry** render mode in the Rendering tab. **Approximate+Shadows** – Same as **Approximate**, but also affects the strength of shadows over the scene geometry. **Approximate+Shadows** is not supported by the **Volumetric Geometry** render mode in the Rendering tab. **Phase Function** – Controls the direction in which the light scatters inside the volume. Negative values correspond to backward scattering, which mimics a volume made up of solid particles and produces denser and more detailed looks. Negative values are more suitable for smoke or dust effects. Positive values correspond to forward scattering, which mimics a volume made up of water droplets where light scatters more. Positive values are suitable for highly scattering volumes such as clouds. The default value of 0 scatters the light in all directions and creates an even and diffuse look. *See the **[Phase Function examples](https://docs-chaos.atlassian.net/wiki/spaces/VC4D/pages/116853677/Smoke+Color#SmokeColor-phaseFunction)** for a visual representation*. **Note** that values very close to **1.0 or -1.0** produce very directional scattering that is invisible from most angles, so such values are not recommended. When rendering with a **Phase Function **different than 0 and **Volume Light Cache** is enabled, the rendered result is brighter. The **Phase function** is ignored when the scattering is set to **Approximate** or **Approximate+Shadows**. **Optimize Anisotropic Scattering** – When enabled, it can greatly reduce the render times for highly scattering volumes such as clouds. Due to certain assumptions made for the optimizations, the optimized render result might produce different results than the exact brute-force anisotropic scattering. The option is ignored when the scattering is set to **Approximate** or **Approximate+Shadows**. **Scatter Depth*** *– Specifies the maximum depth of the GI rays. **Volume Light Cache** – Enables light caching for each voxel of the grid, which speeds up bucket rendering considerably when the voxel size of the grid is significantly larger than the rendering pixel. If the grid resolution is large enough compared to the rendering resolution, disabling this option speeds up rendering. > Macro (ui-text-box) > > 1. This option refers to the internal **Volume Grid Light Cache**, which is not related to the [V-Ray Light Cache](https://docs-chaos.atlassian.net/wiki/spaces/THEORY/pages/116719627). > 2. When using **V-Ray Progressive Rendering**, this option might slow down the rendering startup or the overall render speed. > 3. This feature might produce **artifacts** when the smoke is very dense. > 4. This feature might produce **artifacts** when objects cast shadows through the smoke. > 5. Rendering **multiple copies or instances** of the **Volume Grid** node with this option turned on might lead to slow-downs. > 6. This option will consume additional memory, so beware of high RAM usage when rendering very large cache files or a large number of copied or instanced volumes. > 7. When rendering in [Volumetric Geometry](https://docs-chaos.atlassian.net/wiki/spaces/VC4D/pages/116853681) mode, for any of these Render Elements: [[ Shadows ]](https://docs-chaos.atlassian.net/wiki/spaces/VC4D/pages/116856782), [[ Raw Shadows ]](https://docs-chaos.atlassian.net/wiki/spaces/VC4D/pages/116855478), [[ Global Illumination ]](https://docs-chaos.atlassian.net/wiki/spaces/VC4D/pages/116855432), [[ Raw Global Illumination ]](https://docs-chaos.atlassian.net/wiki/spaces/VC4D/pages/116856758), the **Volume Grid Light Cache** will require additional memory to produce the correct result. **Please be aware that these Render Elements (and most other V-Ray Render Elements except for **[[ Atmosphere ]](https://docs-chaos.atlassian.net/wiki/spaces/VC4D/pages/116855403)** and **[[ Self-Illumination ]](https://docs-chaos.atlassian.net/wiki/spaces/VC4D/pages/116853045)** ) do not work in Volumetric mode**. > 8. This option is ignored when using V-Ray GPU. It is a CPU-only feature that helps speed up Bucket rendering. **Light Cache Speedup** – Valid only when **Volume Light Cache** is enabled. The higher this option is set, the faster the rendering will be, but the lower the quality of the volumetric **Light Cache**. You can increase this parameter and gain render speed as long as you don't start getting dark cubic grid artifacts on the smoke. **Own Light Scatter Mult** – Valid only when **Scattering** is set to **Approximate **or **Approximate+Shadows**. This multiplier determines how far the light travels through the volumetric based on the distance from the emissive light itself. **External Scatter Mult*** *– Valid only when **Scattering** is set to **Approximate **or **Approximate+Shadows**. This multiplier determines how far the light from all external light sources travels through the volumetric. Both Scatter Boost parameters don't alter the visual density of the smoke to the camera and only apply to the illumination. **Master Multiplier** – A general multiplier for the diffuse color. It is ignored when the **Scattering** mode is** **set to **Ray-traced (GI only)**. **Shadow Strength*** *– A multiplier for the opacity of the shadow that the volumetric casts on other objects. > Macro (anchor) --- ### Example: Phase Function with Front Lighting The orange arrow represents a ray of light going through the volume and the possible scattering directions for the ray. --- ### Example: Phase Function with Backlighting The orange arrow represents a ray of light going through the volume and the possible scattering directions for the ray. ## **Smoke Color Gradient** ---