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VRayVolumeGrid is a special kind of volumetric effect that can render effects such as explosions, burning fuel, large scale smoke like from volcanoes, as well as dust, tornadoes, clouds, galactic nebulae and more. The volume grid reads the data from an input cache file (.aur, .vdb, or .f3d) which has been created in advance in another simulation software, e.g. Chaos Phoenix.

Here, you will learn how to load and render such pre-made input files (in this case containing a fire simulation) in VRayVolumeGrid, as well as how to control the volumetric parameters so that the fire looks more realistic.

The scene used for this tutorial contains a simple room setting. The closeup shot is taken with a V-Ray Physical Camera (set to Physical Exposure) that uses real-world camera settings for further realism. Most of the geometries are taken from the extensive Chaos Cosmos 3D assets library.

To download the .aur file used in this tutorial, click the download button below.

To download scene files: 

Want to follow along but don’t have a license?: 

The Fire_Trail.aur is bigger than the fireplace space, because it was simulated in a different scene for a different purpose. However, you can use it in whatever scene you want. For this purpose, just scale it to fit the case.

So let’s move and scale the VRayVolumeGrid to fit the fireplace space better. For smaller flames, you can position the file lower.

Here the volume grid is set as shown on the screenshot.

Note that the GPU Preview option is enabled from VRayVolumeGrid parameters > Preview rollout for enhanced viewport presentation.

Render the scene to see how the default parameters of the Fire_Trail look.

There’s too much smoke and the fire itself needs some more tweaks - mainly of the intensity and color.

Even though the final result of the Fire trails tutorial looks great, when importing the simulation cache in a new scene it looks nothing like it.

This is so because the simulation caches carry only the simulation data, but not the render settings.

The simulation data can be interpreted and rendered in many different ways - you can render the fire as mesh or the mesh as smoke.

If you wish to transfer the volumetric render settings from one scene or Volume Grid to another, you can save a preset with all the settings and export it to a file through the Render presets button in the Rendering rollout of the V-Ray Volume Grid.

Now, let’s adjust the fire color and intensity. You can use the available Fire_Trail.tpr preset file, which contains the final fire settings from the Fire trails tutorial as a starting point or set all the necessary parameters’ values manually from the Volumetric Render Settings.

To save time let’s just load the ready-made Fire_Trail.tpr file. Download the file from the Download Assets button.

Now the fire is less strong and needs a general intensity boost to light the surrounding environment.

Not the fire lights the rest of the objects in the room.

The fire intensity is even along the flames, so let’s tweak the gradient ramp a little further.

The fire intensity looks good but now there is a purple tone in the fire root.