---
title: "Fire Rollout"
canonical: "https://documentation.chaos.com/space/VMAX/113586720/Fire%20Rollout"
format: markdown
---
This page provides information on the Fire rollout in the Volumetric Options dialog.
> Macro (anchor)
## **Overview**
---
This rollout controls the emissive (fire) color of the volumetric shader and the light emitted by the Volume Grid. From here you can control the color and intensity of the emission, and also you can gradually transition between a physically correct and artistic look of the fire. Unlike the smoke color which needs an external light to become visible, fire becomes visible immediately.
UI Path
||Command panel|| > **Modify** tab > **Rendering** Rollout > **Volumetric Options** button > **Volumetric Rendering Settings** window > **Fire** tab
## **General Parameters**
---
> Macro (anchor)
## **Light Emission Parameters**
---
All Fire Lights options are ignored when rendering with V-Ray GPU. Enable Global Illumination from the V-Ray Settings if you need the Smoke and/or the scene to be illuminated by the fire.
When using Global Illumination (GI), the fire illuminates everything (scene objects as well as the Volume Grid's own Smoke) automatically but the rendering takes longer. Turning on **Create Fire Lights** simulates GI by placing light sources in the bright parts of the fire, which gives similar results and renders much faster. The color and power of these lights are adjusted automatically but can be overridden.
The smoke illumination caused by the Volume Grid's own fire can be controlled with the **Self Shadowing** option. If enabled, the smoke obstructs the path of light from the fire, creating a much more realistic look but decreasing rendering performance. To gain back the rendering speed, set **Self Shadowing** to **Grid-based** and decrease the **Light Grid Resolution (%)** parameter to reduce the number of generated lights.
> Macro (anchor)
---
### Example: Self-Shadowing
> Macro (anchor)
### Example: Grid Reduction
---
> Macro (anchor)
## **Color**
---
## **Color Gradient and Intensity/Opacity Curve**
---
When the **Based on** option is set to a grid channel, this grid simulation data must be remapped to render data. The sim data channel is laid out horizontally along the X axis in the color gradient and intensity/opacity curve. The color gradient remaps the sim data from the **Based on** channel to fire color. The curve remaps the sim data to fire opacity (in **Use Own Opacity** mode), or to fire intensity otherwise. The opacity/intensity is mapped vertically on the Y axis.
Simulation data has different ranges, depending on the solver it came from - Phoenix Smoke usually goes from 0-1; Fuel goes from 0-1; Temperature is in Kelvins, so it goes from 300-2000, or a few thousand; Speed is in Voxels/sec, so it depends on the grid size and resolution, but usually goes from 0 to several hundred. Data from other solvers often differs a lot from Phoenix ranges. The channel data range is shown in the gradient and curve with a light-blue range which can change as you scroll the timeline as the temperature in a cache file rises, smoke dissipates, speed changes, etc., so keep in mind that the data range for one frame might not be representative for the entire cache sequence. **You can also check the data ranges for the currently loaded cache file under the Frame Info rollout of the V-Ray Volume Grid.**
**Color** | *ecolorx_t, ecolory_t, ecolorx_s, ecolory_s, ecolorx_v, ecolory_v, ecolorx_f, ecolory_f* – Controls the color of the light as a function of the selected channel's value. This color is multiplied by the **Fire Multiplier** to achieve the final value that will be used. The selected channel's data range is highlighted in light blue.
**Intensity** | *epower_t, epower_s, epower_v, epower_f* – Visible when the **Fire Opacity Mode** is set to **Use Smoke Opacity** or **Fully Visible**. The luminance of the emitted light is determined by the function represented in the diagram control. Along the X axis is the value of the selected **Based on** source channel (Temperature, Fuel, etc.). The color of the light is set by the gradient control above. The selected channel's data range is highlighted in light-blue.
**Opacity** | *epower_t, epower_s, epower_v, epower_f *– Visible only when the **Fire Opacity Mode** is set to **Use Own Opacity**. The opacity of the emitted light is determined by the function represented in the diagram control. Along the X axis is the value of the selected **Based on** source channel (Temperature, Fuel, etc.).
> Macro (anchor)