Thanks for the details Mathieux, very much appreciated! ----------------------------------------------- Ahmidou Lyazidi Director | TD | CG artist http://vimeo.com/ahmidou/videos http://www.cappuccino-films.com
2013/7/3 Greg Punchatz <g...@janimation.com> > Sounds brilliant . I need to see the movie now. > > > > Sent from my iPhone > > On Jul 2, 2013, at 11:19 AM, Mathieu Leclaire <mlecl...@hybride.com> > wrote: > > > Hi guys, > > > > I just wanted to share some information on the shots we did for White > House Down. > > > > First off, there's an article in fxguide that explains a bit what we did > : > > > > > http://www.fxguide.com/featured/action-beats-6-scenes-from-white-house-down/ > > > > > > And here is some more details about how we did it : > > > > We built upon our ICE based City Generator that we created for Spy Kids > 4. In SK4, all the buildings where basically a bunch of instances (windows, > wall, doors, etc.) put together using Softimage ICE logic to build very > generic buildings. ICE was also used to create the streetscape, populate > the city with props (lamp post, traffic lights, garbage cans, bus stops, > etc.), distribute static trees and car traffic. Everything was instances so > memory consumption was very low and render times where minimal (20-30 > minutes a frame in Mental Ray at the time). The city in Spy Kids 4 was very > generic and the cameras where very high up in the sky so we didn't care as > much about having a lot of details and interaction on the ground level and > we didn't really need specific and recognizable buildings either. > > > > The challenge in White House Down was the fact that it was Washington > and we needed to recognize very specific landmarks so it needed to be a lot > less generic. The action also happens very close to the ground so we needed > to have a lot more detail on the ground level and there needed to be a lot > of interaction with the helicopters that are passing by. > > > > So we modeled a lot more specific assets to add more variation (very > specific buildings and recognizable landmarks, more props, more vegetation, > more cars, etc.). We updated our building generator to allow more > customizations. We updated our props and cars distribution systems. They > where all still ICE based instances, but we added a lot more controls to > allow our users to easily manage such complex scenes. We had a system to > automate the texturing of cars and props based on rules so we could texture > thousands of assets very quickly. Everything was also converted to > Stand-Ins to keep our working scenes very light and leave the heavy lifting > to the renderer. > > > > Which brings me to Arnold. > > > > We knew the trick to making these shots as realistic as possible would > be to add as much details as we possibly could. Arnold is so good at > handling a lot of geometry and we where all very impressed by how much > Arnold could chew (we where managing somewhere around 500-600 million > polygons at a time) but it still wasn't going to be enough, so we built a > deep image compositing pipeline for this project to allowed us to add so > much more detail to the shots. > > > > Every asset where built in low and high resolution. So we basically > loaded whatever elements we where rendering in a layer as high resolution > while the rest of the scene assets where all low resolution only to be > visible through secondary rays (so to cast reflections, shadows, GI, etc.). > We could then combine all the layers through deep compositing and could > extract whatever layer we desired without worrying about generating the > proper hold-out mattes at render time (which would have been impossible to > manage at that level of detail). > > > > In one shot, we calculated that once all the layers where merged > together using our deep image pipeline, it added up to just over 4.2 > billion polygons... though that number is not quite exact since we always > loaded all assets as lo-res in memory except for the visible elements that > where being rendered in high resolution. We have a lot of low res geometry > that is repeated in many layers, so the exact number is slightly lower then > the 4.2 billion polygons reported, but still... we ended up managing a lot > of data for that show. > > > > Render times where also very reasonable, varying from 20 minutes to 2-3 > hours per frame rendered at 3K. Once we added all the layers in one shot, > then it came somewhere between 10-12 hours per frame. > > > > We started out using Nuke to manipulate our deep images, but we ended up > creating an in-house custom standalone application using Creation Platform > from Fabric Engine to accelerate the deep image manipulations. What took > hours to manage in Nuke could now be done in minutes and we could now also > exploit our entire render farm to extract the desired layers when needed. > > > > Finally, the last layer of complexity came from the interaction between > the helicopters and the environment. We simulated and baked rotor wash wind > fields of air being pushed by those animated Black Hawks using Exocortex > Slipstream. That wind field then was used to simulate dust, debris, tree > deformations and crowd cloth simulations. Since the trees needed to be > simulated, we created a custom ICE strand based tree system to deform the > branches and simulate the leaves movement from that wind field. Since the > trees where all strand based, they where very light to manage and render. > We also had created a custom ICE based crowd system for the movie Jappeloup > that was updated for this project. We bought a couple Kinect to do in-house > motion capture and build a list of animation cycles of agents reacting to > helicopters flying over their heads. We then procedurally analyzed the > movement of the helicopters per shot and randomly select an animation cycle > from the list and time the cycle in a way that the agents would react when > the helicopters passed within a specified distance of the agents. > > > > > > These where definitely the most complex and technically challenging > shots we ever managed here at Hybride. It was achievable thanks to the > evolution of a lot of in-house tools we had created over the years and > obviously, thanks to a lot of very talented and hard working people in a > very short span of 3-4 months. > > > > > > Mathieu Leclaire > > Head of R&D > > Hybride Technologies, a Ubisoft division > > > > > >
