Guy Ritchie's re-imagined Sherlock Holmes, with Robert Downey Jr. as Arthur Conan Doyle's venerable Victorian sleuth and Jude Law as a more than capable Dr. Watson, contains a meticulously recreated London as well as some explosive action. Chas Jarrett (Ninja Assassin , Speed Racer ), the overall visual effects supervisor, discusses the 850 shots worked on by Double Negative  and Framestore . The vfx ranged from all carriage and boat journeys, all exterior establishing shots and the Baker Street exterior set (only eight houses in a row on one side -- everything else was CG, digital matte paintings and motion controlled people/carriages). In addition, there were several action set pieces, including a villain being set on fire, a slow motion explosion and a madcap ship launch.
However, the mainstay of the vfx is the keen environmental work: a combination of plates shot on location and lots of building replacement, given that the movie takes place in London circa 1891. "Most environment work was based on photos," Jarrett relates. "We would find relevant buildings (hotels, restaurants)."
The Thames is the lifeblood of London and Tower Bridge is still under construction; bridging the Docklands at the East End of the city. However, very few of London's original Victorian buildings survived the heavy bombing of two World Wars. To replace modern London, Jarrett says the Double Negative team (supervised by David Vickery) surveyed and photographed nearly 50 different period warehouses, mills, churches, residential buildings and factories from multiple in London, Manchester, Chatham historic Docks and Liverpool formed the basis of an architectural library that was used to rebuild the Victorian city depicted by archival photography. In addition, more than 100 unique digital work props were created to provide attention to detail and a historically accurate digital world.
"There's a nice high wide shot of a prison early on that I like," Jarrett continues. "The establishing of that is a sweeping 400-foot shot looking down over London with a prison and it's raining and lightening goes off and lights up the whole prison. There were no photos for that: it was CG built.
"Broadly speaking, Double Negative handled the London Bridge sequence at the end, Standish catching fire when his gun backfires and some establishing bits too. Because of limitations of the location, we couldn't have any fire inside the building, so we did digital fire when he first ignites. Double Negative used its proprietary software. And then when he smashes out of the window, there are two shots. One, which is a top shot looking down, with a horse and carriage below, and then we cut to a low angle shot looking up and you see him smashing into the carriage.
"Those were two shots that we prevised early on and actually went to a location and built ourselves a big metal dummy that we could pose and suspended off the rig hanging over the building and set it on fire. And we dressed it up and shot that with multiple cameras. And what was great about that was it gave us all the interaction on the building: all the reflections in the windows, all the moving shadows on the walls, all that stuff came from that plate photography. And, of course, metal being metal, it smashed into the back of the carriage and that's what destroyed the carriage. And after we got those plates, we built a 100-foot tower, and got a stunt man and set him on fire and threw him off the tower and shot that on greenscreen and replaced the dummy in the plate with the stuntman and we also did CG windows. Because we shot the guy for real, it was a lot of fun, there wasn't a great deal of tweaking and noodling those shots in post and people know it's real and don't question it."
However, the digital effect had to match the practical one and so the framing of the fire necessitated a very high resolution as well as the most sophisticated shading and rendering, according to Jarrett.
By contrast, the slow motion exterior explosion uses practical fire, and is Jarrett's favorite scene. "We were on location in Liverpool with Robert and Jude and everybody. That location was real: it was a building that was about to get renovated. We obviously couldn't have any explosions near our actors so we prevised the whole sequence as a slow motion sequence -- 120 frames-per-second. And then we had special effects put air mortars on location, which are these huge cylinders that you can fire air through at really high pressure. And we would have Robert run right past those and replace all of those where the explosions are supposed to be. So that as Robert or Jude would be running, these air mortars would go off and we'd physically blow them and their clothes and you'd get a really strong reaction from this air on them and, of course, they'd flinch and so that's how we got their reactions to these explosions.
"So we filmed all of that on location, no greensreen at all. And then several months later we rebuilt the environment in green, and spent a week with special effects and a motion control camera and reshot those camera moves precisely, blew up stuff and high speed with a motion control camera and then comp'd it in. So those explosions were completely real. I've done CG fire before and it can look great in certain situations but for me, in that situation, where it was slow motion, in particular, where the explosions have to grow organically, I just thought that it would take a lot more effort and not necessarily look as good. So, live action was essential. And we built green replicas of Robert and Jude and often replaced those in the shot, so that the explosions would wrap around those green dummies, so you at least get some sort of fire interaction. And we ended up doing a bunch of CG debris on top of that, and a little CG fire, too, when Robert catches fire."
Another set piece is the ship launch, in which Holmes and Watson are on the run in a ship dock. "We built a set piece of the ship about 20 feet high and 200 feet long," Jarrett explains, "and were able to shoot close up action against that, but when the ship launches, we took the whole set out and completely recreated it digitally, so that we actually did a reconstruction of the building that the ship was in and the ship itself and all the props. It was pretty detailed and had to be big with lots of dynamics in it. There had to be ropes and platforms hanging off it. Once the boat begins to move, everything that supports it is wood and so it had to smash and crash and break. We used a big old dynamic simulation for that. Framestore did that sequence. It was an interesting mixture of shots and everything leading up to that shot was matte paintings."
But the most daunting sequence is the climactic fight on top of London Bridge under construction. "There was a lot of photographic reference for what the bridge looked like, which we used, and a lot of reference for what the buildings around it looked like: the type of boats and all that stuff," Jarrett continues. "The tricky thing was that it was in broad daylight on a bright day and you're up 250 feet in the air looking down on London. And every single bit of it has to be manufactured. There's none of real London that's there now, with the exception of maybe half a dozen buildings. But the most effective approach was to have it be full-CG, with CG water, obviously for the river, and simulations for the debris floating around the river and past boats.
"The buildings about half a mile in all directions from the bridge are full CG with shaders and textures, not just matte paintings projected on. There is a mixture of live-action elements of smoke and atmospherics along with the CG smoke and steam from the boats. Little details were important like trying to keep the sky moving all the time and drifting and having enough smoke and atmospherics, but not to overcook it. We were trying to make sure that every single smoke element looked different and was blown at a different direction or had a different color. We wanted to make sure there was no sense of repetition in the background.
"You know, London is a city with a lot of character -- it's been around for a long time but also different areas within the city have got a very different feeling. So, for example, just to the east of that bridge is Docklands where the historic port was. Up to that point, boats could come up with their tall masts but they couldn't get beyond Tower Bridge, so if you look east it's all the kind of down and dirty London, lots more chimneys, more industrial; if you look west, it's the complete opposite: it's the fancy buildings by the people that own the docks; boats couldn't get up there with tall masts because there's a bridge in the way; only smaller boats and lower boats; there's much less atmospherics. So we were always thinking about what would make it a viable place and I do think it has a nice character, but the hardest sequence in the movie with about 320 shots. And when the DVD comes out, you'll actually see that the buildings are laid out as they were really laid out at the time."
Bill Desowitz is senior editor of AWN & VFXWorld.