Playing with Fire

by Trent Leighton

Trent Leighton Recently at Adam Walker Film, we completed a 30 second TVC for Aurora (agency: Red Jelly) While that may sound simple enough, this TVC required something extra. The commercial was to illustrate the dangers of trees growing too close to power lines.That meant we would need to create lots and lots of fire. Under the direction of Red Jelly we needed to build an idealic rural Tasmanian landscape and then burn it! We required the full spectrum of fire from a couple of burning leaves, to a grass fire, to trees being engulfed, right up to a full fiery inferno. To accomplish this I used a 3ds max plugin called “FumeFX” which allows you to simulate fire based on real world parameters (see below).

Setting things on virtual fire was often fun, even though I didn’t get to try it out on any of our 3d characters. Fume could also be quite difficult to work with. As it’s all simulation based, I needed to do a lot of experimentation to the get the right settings for each fire effect (see below).

The basic workflow for FumeFX is to begin by setting up a Fume Grid that the fire will burn within. You then set up the object that will burn and make sure its within the Fume Grid. You also want to leave ample room in the grid above the burning object so the smoke can rise. A big part of working with Fumes settings is trial and error, making educated guesses on what settings you need, and testing them out to see how they behave.

Next comes simming (simulation). This means the software takes all the data that’s been inputted and generates the fire. So we’re done, right? Unfortunately no, this is where things get complicated.

The fires I was working with were huge and some (most) take all night to sim. That’s if they don’t crash and need to be restarted from the beginning. Even after many smaller scale tests, there would often be problems that require the whole thing needing a resim.

I also had to take many different approaches to creating the fire. For trees, I started a fire at their base and then let the sim burn upwards (see Below).

However, for the grass fire that moves across the field, this approach would have been too random. I needed the fire to be at a certain place at a certain time. Instead I used an animated texture map that allowed me to say exactly where the fire would burn (see below).