Was the location shown here in the finale of Sherlock Holmes, especially at 0:10 - 0:25, actually a real location? Or was it created with CG in post production? I don't know if it's just because of the way the camera moves around it; but it always looked somewhat fake to me.
It was CGI
The Tower Bridge
Recreations of scenes around the River Thames and, in particular, the Tower Bridge under construction, were handled by Double Negative under the supervision of David Vickery. The look and feel of these shots was dictated by a desire to bring the grime and pollution of that era out on film. “Chas Jarret came into Dneg and we showed him some of our work on Cloverfield,” said Vickery. “There was nothing in that picture that was trying to stand out. And that’s what he wanted with Victorian London. He wanted to create the city at that time, not in a typical Hollywood style, but in the seedy way that it would have been – the Victorian underworld, almost. He wanted to see the muck on the floor and the mud on the horses and filth on the buildings.”
Construction of the Tower Bridge was undertaken via traditional modelling in Maya, with elements such as ropes and chains handled more dynamically. “We knew if we had to hand animate every chain and piece of cloth, we’d never finish the movie,” said Vickery. “So we came up with some tools that allowed us to pre-animate the ropes and chains using soft-body dynamics and Maya cloth packages. We have our own in-house rigid body solver called Dnamite. We’d run 500-600 frame caches out which would become invisible in the Maya scene and saved out as a rib archive and would disappear until render time.” A similar system was adapted for the boats and barges inhabiting the River Thames. Recalls Vickery: “Rick Leary came up with a system that, depending on how big the footprint of the boat was, would alter how high it would sit in the water. So row boats would sit quite high and the cargo barges full of lead and iron would sit lower. They all had procedural animation – you wouldn’t have to worry about for every shot.”
To create the digital water for the Thames, Double Negative utilised its water generator dnOcean, adapting the software to achieve the brown, murkiness of the river. “We had to match all the complexities of the swirling currents and waves,” said Vickery. “Basically these are generated by hundreds of different displacement maps controlled with little cordinate systems about the river. We painted the currents and flow paths, even down to the underlying geometry of the river. dnOcean allows us to make the water change movement depending on that geometry.”
The final fight sequence on the Tower Bridge, featuring Holmes, Blackwood and Adler, was filmed on a complete greenscreen set in New York, which also utilised a 75 foot section of walkway. Previs helped the filmmakers work out interesting shooting angles in terms of whether the bridge or the river would be seen in the background. At Double Negative, Vickery again relied on a rendered spherical map for the backgrounds, with a walkway extension rendered in 3D for appropriate parallax movement.