The Pyro Bake Volume node contains a Pyro Shader, which is automatically assigned to the processed volumes. The embedded shader references parameters on Pyro Bake Volume to ensure that the render matches the viewport. Therefore, you can create copies of the Pyro Bake Volume node and render different variants without adjusting material assignments at the object level.

Although most of the Pyro Shader’s features are available on the Pyro Bake Volume node, there are a few extra parameters on the shader that are not available in the viewport. To see the effect of these parameters, you need to render the volumes.

The following are additional things you can control with the Pyro Shader.

• Clamp or remap the smoke density, or scale it by another volume (such as temperature) with the Use Control Volume parameter.

• Set the Smoke Brightness.

• Change the color of the smoke using absorption with the Absorption Color parameter.

• Change the color of the shadows with the Shadow Color parameter.

• Set the Scattering Phase.

1. Turn on Enable Scatter on the Scatter tab.

2. Turn off Enable Mask to visualize the full extent of the scatter without masking.

3. Know your maximum temperature values on the frames you are testing, and adjust Source Range accordingly.

   • By increasing the minimum value of Source Range, you will cut off the low temperature values so they will not contribute to the scattered emission.

   • First set the maximum value of the Source Range. To find an appropriate setting, you can begin by calculating the maximum temperature value over a few sample frames. The average of these values can serve as a starting value, and you can tweak it further to fine-tune the look.

4. Adjust Scale and Hot Core Scale for the intensity of the scatter.

5. Change the amount of blurring based on the size of your simulation. Turn on Use Blur Steps to further smooth out the scatter area.

6. Examine frames from the beginning, middle, and end of your simulation while refining the aforementioned parameters.

7. Turn on Enable Mask and find values for Mask Center and Mask Width that produce the desired results in the viewport. Alternatively, you can break the material reference and examine renders as you tweak parameters on the assigned shader.

The combination of these two components make up the final volume render. Some renders such as chimney smoke, dust clouds, and other generic smoke elements only need to be shaded as smoke. Smoke is mainly controlled by its density and color. Emission on the other hand, controls the overall intensity and color of light emitted by the fire.

Each of these components relies on a set of volumes to do its work. A density volume is usually bound to the smoke component, and parameters in the Smoke tab control its resulting look. You can use up to 3 emissive elements with this shader: scatter, fire and secondary fire.

Scatter uses a scatter volume produced by the Pyro Bake Volume SOP, which can have the effect of internal scattering pre-baked. Although this scattering is an approximation to true behavior, this approach is much cheaper to render compared to using volume lights and a high number of volume bounces. It also gives you greater artistic control over the look.

Fire and secondary fire provide a more traditional set of controls that mirrors Pyro Shader - Classic. In particular, each of these emissive elements needs an intensity and a color field, governing the amount and color of the emitted light, respectively. Similar to scatter, fire can also be masked by another volume.

The following are the main differences between Pyro Shader (introduced in 18.5) and Pyro Shader - Classic.