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Adjusting Density and Color in Cached Niagara 3D Fluid / Gas Simulations in Unreal Engine

Writer: Rahul GuptaRahul Gupta

Niagara does not have the option ( as far as I know ) to modify parameters of cached smoke / gas simulations.

Once your simulation of cigarette smoke, chimney smoke, etc is cached, the attributes are baked in. Once you've cached your simulation—whether it’s cigarette smoke, chimney smoke, or any other gaseous effect—the attributes are baked in. There’s no built-in way to access and adjust them afterward. This can be frustrating, especially when you’re happy with how the simulation moves but find that changes in lighting make it look off. Normally, the only solution would be to recache the entire simulation, which can be time-consuming and inefficient. Unlike traditional fluid simulations that rely on materials for their final look, Niagara’s fluid sims don’t offer that flexibility.

Here’s the approach I’ve been using to solve this issue:

  1. Cache the Niagara Simulation

    • Ensure your Niagara simulation is cached in a Level Sequence.


      Adjusting Density & Color in Cached Niagara 3D Fluid Simulations in Unreal Engine – Niagara doesn’t allow modifying cached smoke or gas simulations directly. To adjust density and color without recaching, use lighting. Add an Area Light, set its lighting channel to match the Niagara system, and increase Volumetric Scattering Intensity. Adjusting the light’s intensity and color will dynamically influence the smoke’s appearance, offering a quick and efficient way to refine your simulation.

  2. Create a Light Source

    • Add a light to your scene (e.g., an Area Light).

    • Position and rotate the Area Light so that it points toward the Niagara simulation.


      Adjusting Density & Color in Cached Niagara 3D Fluid Simulations in Unreal Engine – Niagara doesn’t allow modifying cached smoke or gas simulations directly. To adjust density and color without recaching, use lighting. Add an Area Light, set its lighting channel to match the Niagara system, and increase Volumetric Scattering Intensity. Adjusting the light’s intensity and color will dynamically influence the smoke’s appearance, offering a quick and efficient way to refine your simulation.

  3. Adjust Lighting Channels

    • Select the Area Light and go to the Details tab.

    • Locate the Lighting Channels section.

    • Change the lighting channel from 0 to 1 or 2.

    • Ensure the chosen lighting channel is not already in use by other objects or lights unless you want them to be affected as well.

      Adjusting Density & Color in Cached Niagara 3D Fluid Simulations in Unreal Engine – Niagara doesn’t allow modifying cached smoke or gas simulations directly. To adjust density and color without recaching, use lighting. Add an Area Light, set its lighting channel to match the Niagara system, and increase Volumetric Scattering Intensity. Adjusting the light’s intensity and color will dynamically influence the smoke’s appearance, offering a quick and efficient way to refine your simulation.

      Adjusting Density & Color in Cached Niagara 3D Fluid Simulations in Unreal Engine – Niagara doesn’t allow modifying cached smoke or gas simulations directly. To adjust density and color without recaching, use lighting. Add an Area Light, set its lighting channel to match the Niagara system, and increase Volumetric Scattering Intensity. Adjusting the light’s intensity and color will dynamically influence the smoke’s appearance, offering a quick and efficient way to refine your simulation.

  4. Modify the Niagara System's Lighting Channel

    • Select your Niagara System and apply the same lighting channel value as the Area Light.


      Adjusting Density & Color in Cached Niagara 3D Fluid Simulations in Unreal Engine – Niagara doesn’t allow modifying cached smoke or gas simulations directly. To adjust density and color without recaching, use lighting. Add an Area Light, set its lighting channel to match the Niagara system, and increase Volumetric Scattering Intensity. Adjusting the light’s intensity and color will dynamically influence the smoke’s appearance, offering a quick and efficient way to refine your simulation.

  5. Adjust Volumetric Scattering Intensity

    • Select the Area Light and increase Volumetric Scattering Intensity to 4.0.


      Adjusting Density & Color in Cached Niagara 3D Fluid Simulations in Unreal Engine – Niagara doesn’t allow modifying cached smoke or gas simulations directly. To adjust density and color without recaching, use lighting. Add an Area Light, set its lighting channel to match the Niagara system, and increase Volumetric Scattering Intensity. Adjusting the light’s intensity and color will dynamically influence the smoke’s appearance, offering a quick and efficient way to refine your simulation.

  6. Fine-tune the Light Properties

    • Now, adjusting the light’s intensity and color will influence the Niagara simulation.

    • Increasing intensity can create a denser smoke effect.

    • Changing the light color will modify the color of the Niagara simulation.


      Adjusting Density & Color in Cached Niagara 3D Fluid Simulations in Unreal Engine – Niagara doesn’t allow modifying cached smoke or gas simulations directly. To adjust density and color without recaching, use lighting. Add an Area Light, set its lighting channel to match the Niagara system, and increase Volumetric Scattering Intensity. Adjusting the light’s intensity and color will dynamically influence the smoke’s appearance, offering a quick and efficient way to refine your simulation.

      Adjusting Density & Color in Cached Niagara 3D Fluid Simulations in Unreal Engine – Niagara doesn’t allow modifying cached smoke or gas simulations directly. To adjust density and color without recaching, use lighting. Add an Area Light, set its lighting channel to match the Niagara system, and increase Volumetric Scattering Intensity. Adjusting the light’s intensity and color will dynamically influence the smoke’s appearance, offering a quick and efficient way to refine your simulation.

 
 
 

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Based in Miami, Gnomon graduate with over 2 years of experience, recognized with four best-of-term awards and Rookie of the Year Finalist. Proficient in creating photorealistic effects using Houdini & Unreal and implementing procedural pipeline workflows for pre-rendered and real-time FX.

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Rahul Gupta

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