Burning the candle at both ends

With less than three weeks left of the project, animation was finished to a point where I could start adding fire and smoke to finished shots. Having used FumeFX in the past, it became the natural choice now.

I anticipated this to be a fairly simple task, but didn’t have to work long before it became clear that I had greatly overestimated the ability of 3ds max plugins to work properly together. Having successfully used FumeFX with V-Ray before, it never occurred to me that one tiny change would throw the whole thing off balance. It did though. As it turns out, FumeFX works perfectly with V-Ray as long as you don’t use the V-Ray daylight system. Light from the V-Ray daylight system is almost infinitely brighter than normal lighting in 3ds max, and the only thing keeping the images from turning out simply white is the VRayPhysicalCam which dials the brightness back down again. As to why the daylight system behaves in this peculiar way, I have no idea. The problem surfaces when you wish to put a flame from FumeFX in this environment. FumeFX uses normal brightness values for its flames, and when the VRayPhysicalCam reduces the brightness by a factor of a thousand or so, the FumeFX flame is simply too weak to register in comparison and ends up invisible. I spent a day or two, looking for a solution, but didn’t find one and was left with two choices: Getting rid of the daylight system, relight the scene and scrap 30-40 shots already rendered, or render the FumeFX elements alone and composite them over the rendered shots afterwards. Being pressed for time, the compositing route was the only option if we were to finish on time. There are a fair few advantages to this, such as being able to adjust the brightness and colour of the FumeFX elements without affecting the rest of the image and being able to adjust fire and smoke separately, but it also comes at a prize as you no longer get out of the box integrated smoke shadows. The case with the V-Ray daylight system this is particularly irksome as FumeFX doesn’t even see the sun as a light source for generating shadows. My solution was to create a Direct light in the same position as the sun and using that instead, but it didn’t always yield the best results.

Having decided on a workflow, I started work and the rest of the process was fortunately pretty straight forward. I finished the FumeFX shots in a little more than a week while rendering and compositing other shots at the same time. Having finished, it was time to proceed to the final compositing.