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Is it true your team wrote a volumetric renderer specifically for the geysers unleashed by R'as? What does it do that other renderers couldnt?
When we broke down the Monorail chase and fight sequences which feature the effects of the Focused Microwave Emitter we decided that we would need to create CGI steam elements that exactly matched the quality of the on-set special effects created by Chris Corbould's team. We had previous experience of some of the commercially available volume rendering tools and concluded that whilst they were sometimes capable of quite high quality results that they were all way too slow for the amount of rendering that we would have to do.
Our R&D team took the bold step of developing "DNB," a fully featured, standalone volumetric renderer that supports its own shading language and which integrates with our 3D render management system. DNB is a highly optimised and robust rendering system and produced great results for us -- the render times were dramatically better than any commercial package and we were able to add digital steam to a far larger number of shots than we had initially been assigned in this area. Since finishing Batman Begins we have used it with great success on several new projects. DNB continues to be developed and is the core of our approach to rendering naturalistic VFX elements such as smoke, fire and vapour.
|Batman swings through the steam jets as he desperately tries to ascend to the monorail train. This shot is 100% digital. Double Negative developed DNB, a new rendering package to create steam plumes that matched perfectly with the practical effects on set.|
How did you match Batmans flowing cape for the fx shots? The texture and movement of the cape seems very natural and consistent throughout.
Chris Nolan was keen that the Batcape should be much more mobile and active than in previous Batman films. To capture the complex nature of the cape's movement, we spent a lot of time studying the characteristics of the material; in some cases this involved Double Negative staff dressing up in the cape and jumping off ladders, running around in front of wind machines, etc.! All of this information was then used to develop a sophisticated simulation of the Batcape's mechanical qualities using the Syflex cloth sim plug in for Maya.
The simulation produced was very complex, so we developed a number of additional tools to help manage the weighty datasets produced by this process. We also created a precise Bi-directional Reflectance Distribution Function (BRDF) measurement system that enabled us to create a shader set that accurately captured the subtle qualities of the cape's appearance as well as the look of the rest of the costume. Finally, we spent lots and lots of time studying how the cape looked on film and making sure that the animations that we produced really were as close a match as possible to the capes in the live action.
|Batman drops down out of the swirling fog to confront R'as. During the flying sequence the digital stunt double was used primarily for moments when the Batcape transformed from loose flowing cloth to the hang-glider-like flying rig. Cloth simulation was performed with a combination of Syflex and homegrown tools.|
At the outset of production, Chris Nolan was concerned that a digital Batman would be at odds with the live action stunt work that he intended to shoot. Chris's goal was to achieve as much of the stunt work in camera as could be managed, he felt that a digital version of Batman would not have the necessary believability as CGI is an inherently "weightless" environment that can encourage the production of characters and animations that loose their connection to reality. In order to demonstrate that we could make a really great-looking digital Batman, we set about creating film tests that would hold up next to the live action.
To create the models, we used a company called Eyetronics to scan Christian Bale in full costume and then built a very detailed animation rig that was based on where we determined all of Christian's skeletal joints to be. As stated earlier, we developed a whole new BRDF shading pipeline to create the correct look for the Batsuit. We then put the whole lot together and used it to make a test shot where we created an exact match for a live action take of Christian on set in full costume. The results were put to film and projected side-by-side with the original material. When Chris Nolan felt that they both looked the same we knew that we had cracked it.
For the shots in the movie we developed a process that allowed us to closely analyse the actions of the stunt performers and then replicate this in key frame animation, no motion capture was used at any stage. The vast majority of Batman's stunts were achieved in camera and our digital stunt double plays mainly in shots that were just impossible to achieve any other way.
Were there any special considerations for you during production because the film was released in IMAX also?
No, we output all of our material through the pipeline that was defined by Janek Sirrs and Dan Glass, the overall VFX supervisors for the show. The fact that it all holds up so well is a testament to the quality of the work produced.
What was your favourite shot in the movie?
I was so close to the show for such a long time that it is hard to pick one out, but one of my personal favourites is a shot during the final train chase when the Batmobile, driven by Jim Gordon, is just getting ahead of the train. You see the car turn the corner and descend a ramp to the underground freeway; the camera follows behind it tilting up as it goes to reveal Wayne Tower in the distance.
This shot was never originally intended to be a VFX shot and did not feature the tilt action. Double Negative VFX artists completely removed everything above the level of the crash barriers surrounding the ramp and replaced it with a 100% digital street scene that blends seamlessly with the live action and which captures all of the complexity of the streets of Gotham. What was particularly impressive about this shot was that it was added to our list very late on in post production and was turned around in by the team in just under three weeks from start to finish.
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