Working on a series provides a lot of benefits for the artisans at PDI/Dreamworks as they are able to continually tweak the process to their advantage. Much of the staff has worked on all three films at PDI -- starting at the top with first-time Director/Writer Chris Miller and Co-Director Raman Hui. Not only can the crew revisit characters, but advances in technology also allow greater flexbility in creating effects to enhance the storytelling.
Lucia Modesto has a lot of history in the series, working on all three as Character Technical Director Supervisor, along with co-supervisor Larry Cutler on the last two films.
Head of Effects for Shrek the Third Matt Baer is also a longtime Shrekster, having worked as an effects animator on the first Shrek and an effects developer on the second film. Since the first film, fire has played big effects role in the series and the third is no different. What is different in this film is the role in which it plays and the way in which technology advancements have enabled it.
"On the effects side we were able to do more complex simulations," says Baer. "On the first film we had to be a lot more picky and not be able to use as large of a simulation or as complex of a simulation so with respect to fire on Shrek the Third we were able to use fluid dynamics...That in general has just become much more accessible to the artist where on Shrek 1 it would have been way to slow for the artist to deal with on a lot of different shots using that type of system."
Knowing that fire would be used on a much larger scale in the film, a lot of time was spent early on figuring out a balance between being able to coreograph the flames and keeping render times low. Another important aspect was how to accurately choreograph the flames for the story, yet keep render times at a minimum. In the end this was done by being able to actually dynamically resize the effects grid on a frame by frame basis to make it only as big as needed.
This enabled fire to be used to help tell the story in comedic ways throughout the film -- something that would have been unheard of before. For artists like Baer it was nice change from the more common atmospheric and other transparent effects that they are tasked with adding to scenes. "There is satisfaction in that," says Baer, "but it is so nice to be able to say 'oh my gosh people are actually going to see this...and I had to come up some really creative ways of hitting these non physical timings, so truthfully its great." It's not an easy process, as that while fire needs to act in realistic, physical ways often the timing of comedic effects must drive the animation.
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The first steps in creating fire and other effects is to develop the base using fluid dynamics in Maya. This is used for most particles such as fire and gasses -- but PDI/Dreamworks has their own fluids simulator for actual fluids. Work is done in Maya because the application and UI have been developed over the years to make creating iterations easy and interactive for the artist. Lots of variations may be tried in a short amount a of time. Once the desired result is obtained, very little actual data is passed out of Maya -- in fact, as little as possible -- which is then fed into their proprietary pipeline and enhanced with in-house tools.
Magic is another hero of the effects department at PDI/Dreamworks -- and with each new Shrek installment there is call for variations that have never been seen before. "Part of the desire is to make something new so the audience sees a new type of magic, "says Baer. "so that's part another constraint as well...'you don't want it to look like any magic from any other movie and we don't want it to look like any other magic from the other Shrek movies but it still has to fit into the Shrek world..so there are these kind of loose guidelines."
To this end, the magic effects are very much in the eye of the beholder, so a lot of time was spent developing the looks. In fact, almost a third of time in creating the shot is spent experimenting with the look...talking about what the magic is and how it acts in the scene. As the process continues the artists are evenutally able to target into the final look. "It's fun but you really have to have a lot of endurance to work on one of those effects," says Baer. "You can't get your feelings hurt...you end up throwing away a lot of really great ideas."
Co-Character Technical Director Supervisor Larry Cutler
fxguide's John Montgomery 'on-set' at PDI/Dreamworks