Tutorial 05: Wavelet Turbulence


In this tutorial you will learn how to add more detail to simulations using Wavelet Turbulence feature.


In Maya, select File->Open Scene, and from your [MAYA]/FumeFX/Tutorials folder, select the file Tut_05_start.ma.


This tutorial essentially begins where Tutorial 4 has finished.


You might have noticed that Tutorial 4 could have benefited from more detail, especially in close up shots. This could be done by decreasing Grid Spacing parameter to value of 0.2 or even 0.1, which would create a simulation with many more voxels. However, reducing Grid Spacing has great impact on memory requirements and simulation time, so we'll try another approach called Wavelet Turbulence. Thanks to this method, it is possible to create a detailed version of a simulation based on an existing, low detail simulation quickly and efficiently.


Because Wavelet Turbulence uses its own caches for output, make sure that inside the FumeFX Preferences, Auto Synchronize Paths is enabled.



On the FumeFX Output rollout, change the Default Path so that it is valid on your machine. Since we have Auto Synchronize enabled, Wavelet Turbulence's Output path will be changed automatically.

Under the General Parameters we will leave the Spacing to 0.4.

Select the Simulation->Extra Detail rollout and scroll down to the Extra Detail rollout and change Mode to Wavelet Turbulence.



You will notice that Export Velocity (Output rollout) has been automatically grayed out and that user cannot affect it. This is because the velocity channel is essential for Wavelet Turbulence computation and it will always be saved with wavelet caches.



By using the Extra Detail option, Default simulation will pre-compute all the data required for Wavelet Simulation Step.


TIP: If you are starting a scene from the scratch and you have Wavelet Turbulence on your mind to enhance a simulation, you will need to select this option only when you're satisfied with how your low detail simulation looks. This option adds to overall simulation time, so there is no need to have this option selected unless your next step is to create a Wavelet Turbulence simulation.


Open a Preview Window and click the Simulate button.


When the simulation is complete, open the Wavelet Turbulence rollout and set Grid Detail Scale to 2.0. This will create a final grid that is equal to Grid Spacing of 0.2 ( Grid Spacing/Grid Detail Scale -> 0.4/2.0 = 0.2).


Under the same rollout, enable the Fire and Smoke checkboxes and change Fire Strength to 4.0 and Smoke Strength to 4.0. This will create more pronounced Wavelet detail. We do not want velocity channel to be saved into the WT file, so enable Exclude Velocity Channel checkbox.



Now, you need to change Sim. Mode to Wavelet so that you can create the extra detail in another simulation pass

You will notice that Start and Continue buttons in the FumeFX UI change with the Sim. Mode change.


Before clicking on the Simulation Start button, make sure that Cache is set to Default.


Click on Start Wavelet Simulation button and wait until simulation is done.



To be able to view what the Wavelet Simulation has computed, you now need to change input cache. To do that, you need to select Wavelet from the Cache dropdown list.



Now, if you render both animations, you will notice that Wavelet simulation kept the same motion from the Default caches, but has added more detail.


Just as a summary, in order to create additional detail in a low resolution simulation, you need to do the following:


First, create a lower detail simulation using a Default cache.

When you get motion that you like, within the Simulation rollout go to the Extra Detail rollout and change the Mode to Wavelet Turbulence ??? and run another Default simulation to pre-compute the data required.

Next, change the Sim. Mode option to Wavelet, change parameters within the Wavelet Turbulence rollout and then run your Wavelet Turbulence simulation.

Finally, to see and render the results, switch to the Wavelet Cache in the FumeFX Attribute Editor.