SIGGRAPH Panel Looks at the Challenges of ParaNorman
Panelists included visual effects supervisor Brian Van’t Hul, compositing supervisor Steve Emerson and LAIKA VFX supervisor Andrew Nawrot. The panel shared with attendees some challenges and achievements of the creative teams who all worked together to fuse stop-motion puppetry and CG animation into a cohesive visual feast.
Emerson shared that one key issue that had to be addressed was cooling digital SLR cameras as they were used for days at a time. Digital SLR cameras are not designed for capturing sequential images over the course of days. By the end of a long day of image capturing, the sensors in these DSLRs would heat up. This caused a kind of camera flicker in the blacks, as the camera started out cool at the beginning of the day, but was at a higher temperature after a full day’s use. When this happened, a majority of the images were unusable.Remedies for this included building camera-cooling systems as well as checking, re-checking and testing voltage regulators.
One solution involved taking a sample of the black values from the first frame of a scene and those same values at each subsequent frame. By taking those values and finding the difference between the first frame and each subsequent frame, they were able to achieve a nice, even curve across the histogram.
“And this works great if you have a shot that’s locked off and you’ve got a very specific area to sample that black, but the problem is that’s by no means the case,” Emerson said.
Often times, because of so many things going on in these very active shots, this solution was not always applicable. This meant the teams at LAIKA had to develop a whole arsenal of fixes for this issue that could be used for various shots. However, one solution required more patience and vigilance than the others.“In the true spirit of stop-motion animation, a few times I had to go to an animator’s and say, ‘You’re just going to have to sit here and key frame that thing, one frame at a time, until that’s gone,’” Emerson explained.
Another aspect of the feature that required special attention was addressing crowd scenes. Nawrot explained some of the approaches taken in the management of these scenes, including developing an in-house crowd system and multi-pass shots wherein an animator would shoot a pass of the foreground of the puppets, and then go back and add in extra background puppets. This allowed animators easy access to background without affecting the foreground, and also gave animators less to manage at one time.
“Somebody once asked me, ‘Why do stop-motion? Why not just do CG?’” Van’t Hul said. “And for me, it’s like, ‘Why would you paint a portrait when you could take a photograph of somebody?’”
“When you see a really amazing performance come up in dailies, it’s a constant reminder of why we’re here trying to preserve this as an art form.”