The heart of FumeFX resides within its simulation engine. This entire, quite sophisticated system is built around a very simple object called the FumeFX Grid. You can think of the FumeFX grid as a 3-dimensional representation of a volume in which the simulation of smoke and fire will take place. Whatever size volume you define when you drag out the FumeFX grid will act as a set of boundaries for the simulation.
In order to create a FumeFX grid in your scene, simply go to the Create Command Panel and from the Geometry dropdown menu, select FumeFX -> FumeFX.
Once selected, like any other object inside of 3ds Max, simply drag out the new volume in any viewport. When done, you'll get a yellow rectangular wireframe box like the one shown below.
The FumeFX Grid
Note: Unless you're using "Boundless" grid options, no simulation will take place outside of this volume.
Since FumeFX is based on real-world computational fluid dynamics, something to consider is the scale of your scene. Just like other simulation engines, you will get unpredictable results if your scenes are microscopic or gigantic in scale. Imagine a matchstick simulation where the geometry is over a mile long in real-world unit - the precision and accuracy of the simulation would not be to the correct scale of the desired result, so be sure to watch the scale of your scenes.
It is important to realize that within the Grid is a set of voxels (Volumetric Pixels), and the density of this volume can be manipulated to get higher or lower precision within the same space. The volume within the FumeFX container is automatically sub-divided into a set of equal sized rectangular "cells", stacked on top of one another, and each one is designed to contain data pertaining to the simulation within them. Since artists are visual by nature, users can visualize this grid at any time to get a better idea of how much detail their simulation will have.
FumeFX Volume Grid display (lower resolution)
FumeFX Volume Grid display (higher resolution)
Note: It is important to remember that the higher the detail within the volume, the longer the amount of time it will take to run the simulation and the larger the amount of storage it will require. See the System Requirement explanation in the Overview to help you determine your storage requirements.
Once you've gotten your FumeFX Grid placed within your 3ds Max viewports, it's time to go to the Modify Command Panel.
With the FumeFX Grid selected, you'll be presented with the controls and rollouts necessary to access the power within FumeFX and also serves as a starting point for your interaction with FumeFX. It contains two rollouts: General Parameters and Viewport. From these rollouts you can access other parts of the interface, edit your preferences, modify parameters of the FumeFX Grid, or control the way that your simulation appears in the 3ds Max viewports.