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MillimeterStep by Step: Hotel for Dogs
Feb 6, 2009 12:00 PM, By Ellen Wolff
Murphy’s Law predicts that if anything can go wrong, it will go wrong. It’s often invoked by moviemakers, and one snafu really complicated the visual-effects assignment on the DreamWorks/Paramount hit comedy Hotel for Dogs. Before Director Thor Freudenthal could get a key shot that he wanted of the hotel itself, a fire on the famed Universal Studios back lot destroyed the practical set. Visual Effects Supervisor Ray McIntyre Jr., of Los Angeles-based Pixel Magic, was watching the evening news and recalls hearing of the event. “I definitely knew that the fire had changed the scope of our shot,” he says.
What the director wanted was a camera boom down the façade of an old hotel that an intrepid band of kids had secretly turned into a refuge for stray dogs. The bottom floors of this hotel were on the Universal lot, and the upper floors had never existed—except in the computers at Pixel Magic. “Most of the buildings on the lot are two stories high," McIntyre says. "We’d already extended the height of the buildings and surrounding locations in many shots, so we had the architectural geometry for the upper stories. But we’d never built the bottom floors, and then they burned down. Fortunately, I had lots of still pictures of it.”
The shot which the director wanted called for a camera boom that would take in multiple stories of the ornate façade and then end at street level, where the hotel was welcoming people. “The original intent for this shot—since you could never practically do a camera move like you see here—was to start the shot tilted up at the building we were adding, and then tilt down to the street level," McIntyre says. "Once the building burned down and we could no longer shoot any plate, it freed us up to do the big boom down. So had the Universal building not burned, we may not have had this camera move.”
The forensic reconstruction of this building required two main sections. Second Unit Director and Executive Producer Ivan Reitman would shoot a stand-in street-level building swathed in greenscreen. Pixel Magic would digitally alter the building’s entrance to resemble the Universal backlot building, add the CG upper floors, and then create a CG camera boom down that would hook the two parts together. “We shot in front of the Park Plaza Hotel in downtown LA,” McIntyre says. “We needed a 90ft.-long greenscreen.”
Back at Pixel Magic, McIntyre’s team modeled, textured, lit, and rendered the building in NewTek LightWave 3D. They were able to deduce the information they needed about the Universal building from the photographs that McIntyre had taken. “The photographs were not from the height that was needed for this shot,” he says. “But they were from the correct angle. I knew the lens I had used to shoot the stills, and approximately how far away from the building I had been. So in 3D, we used an equivalent lens and lined it up.
“The upper stories of the building are based on the look of three different practical buildings. The very upper part, which you see at the beginning of the shot, has a recessed courtyard. That is from a practical building in downtown Los Angeles that actually exists at street level. We matched the look of that courtyard section and the look of the lower section from the Universal lot. We also had to create a middle section that connects the two together. So the building was made in three different pieces. It took a bit of time to make the middle fit.”
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The ground-floor entrance to the hotel was digitally extended and dressed by Pixel Magic with greenery. But the sidewalk looked a bit bare, and McIntyre needed to populate it with some extras. “So we shot more people, including my two kids, in the parking lot at Pixel Magic,” McIntyre says. “I got up on the roof and shot down at them to match the angle of the shot. We shot the people static because the camera wasn’t motion control in any way, which is not to say you can’t figure it out with today’s technology. We could have done a 3D match move and then exported that camera move to a motion control camera system and shot it as a tilt down. Shooting them static was a bit of a cheat, but they were going to be so small in the final frame that it worked out well.”
The Pixel Magic extras were then rotoscoped and composited into the shot with Adobe After Effects. The rotoscoping itself was done with a tool from Imagineer Systems called motor. “Its advantages are that it has some intelligence in the software, in the sense that if you put your rotoscope splines around a person and that person moves over time, the software is smart enough to try and determine that motion on its own and place the splines for you," McIntyre says. "So instead of having to rotoscope every frame, in the end you may do it on every 10th or 20th frame. Basically, it tells the software, ‘On frame 10, the figure is here, and on frame 20, it is there,’ and it tries to interpolate between them. Depending on what you want, you can put keyframes on whatever frames you wish. It’s a somewhat automated rotoscope tool.”
The final part of the assignment was to hook up the pure CG building levels with the pieces shot at ground level, and make the CG camera boom look fluid. “We spent a fair amount of time making sure that there was no bump in the hookup, so as the camera booms and tilts down, you don’t see any hint of the connection—no hesitation or bump. It took us a bit of time to get the move to be seamless,” McIntyre says. “These are hidden effects that I hope most people will never notice. If you watch a camera move like this, you know there’s no other way we could have done this. But then nobody had ever expected we’d lose the building at Universal, either.”
Credit Roll:
Director: Thor Freudenthal
Second Unit Director/Executive Producer: Ivan Reitman
For Pixel Magic:
Visual Effects Supervisor: Ray McIntyre Jr.
Visual Effects Producer: George Macri
Lead 3D Artist: David Ridlen
Lead Compositor: Brad Moylan
Continue the discussion on Crosstalk the Millimeter Forum.