FumeFX...

For a game the conventional method of painting a set of semi transparent clouds and rigging them to a basic particle system is the normal convention but for a full blown animation there are more options to choose from. The best solution at the moment for creating effects such as dust, flames and fumes are by far volumetric particles since instead of using intersecting planes these primarily use voxels to fill an area with a semi-transparent 'fog'. Using the voxel method dynamic fluid effect can be simulated realistically with buoyancy and temperature etc.

FumeFX is one of the leading pieces of software that convert 3D objects onto volumetric sources and one of its ground breaking features is the possibility to simulate fluid effects including velocities. My particle effects where created using thinking particles so the fluid simulations where not necessary to my dynamics and the reason for me not using the physics from the FumeFX alone is because it cannot shape the voxels it can only simulate. For my simulation i had disabled most of the physics since they had been created using the particles themselves but i did use it to simulate and animate fuel, smoke and dissipation. Overall the combination of thinking particles to shape the explosion and then simulation them with FumeFX to convert them into volumetric voxels provides unparalleled control over the system. With the particle voxel combination the dust and explosions can be simulated but its Vray that really brings the cake to the table, Vray is able to understand volumetric particles and not only illuminate them but it scatters the light within the voxels themselves to calculate optical density including changes in colour.

Finally one system i had discovered simply by chance is that setting up a camera for the particle system alone allows me to separately render a z-depth pass on it allowing very easy post production tweaks. Withe the z-depth alpha maps, as the particles develop they can be reshaped re coloured or or even removed entirely.