The Heart of the Earth

Apr 08, 2007

The director, Antonio Cuadri (Riotinto: El latido de la tierra, Eres mi héroe, La Gran vida) wanted to establish the geography in order to show that the town was “physically hanging” over the edge of the mine, as it used to be in 1889. So for the establishing shots, the town needed to be generated either digitally or with miniatures.

About five weeks of shooting took place in the mine. The mines had to show how the “natives” worked from dusk ´till dawn digging and carrying minerals out of the mine. To quote the director Antonio Cuadri “ The British town of Bellavista has to resemble the Heavens, Riotinto the purgatory, and the mine has to be Dante’s inferno. We have to clearly see a town being exploited by the British in order to understand the reasons for the revolt that takes place later in the story”

Until five weeks before the shoot, the production had no access to the actual mine. A Swiss company was buying the mine and getting the permits became a nightmare for the film makers. At some point, the production had the idea of digging a 1:10 scale hole in the ground 150 meter wide hole x 100 meters deep, but finally the permits arrived.

When the production team first went to scout the mine, the real problems started to appear. The mine had been abandoned for over 50 years, and it was crumbling down. There was no possibility of dressing the mine with machinery, trains and with the 70 wooden perforation towers, let alone placing extras inside the mine.

The director also wanted to do some aerial shots inside the mine. The first thought approach that was investigated was flying a helicopter in with a Wescam. That proved impossible due to the thermoclines inside the mine. The north face was in sunlight during the morning, that caused that face to warm up while the south face was in shadow. That created a downward draft in the south face and an upward draft in the north face, making it impossible to fly a helicopter inside the mine. The only possibility was to keep the helicopter 500 meters above the rim of the mine. As director needed the camera to fly inside the mine, the production went to the team at Flying Cam in Belgium. The Flying Cam system consists of a radio controlled helicopter with a camera mounted on its nose. The system allowed the production to fly deep into the heart of the mine. But it was not without many technical challenges. The radio reach of the camera operator was only about 150 meters. "So for the money shot we had to follow the helicopter with a chase vehicle, thus keeping the helicopter in range of the pilot for as long as possible. As the RC helicopter climbed up one of the walls of the mine, it was picked up by a second “pilot in relay”. That is, when the first pilot starts to lose range of the helicopter, a second pilot picked it up in mid flight thus extending the range on which the helicopter could fly. We had a total of 3 pilots in relay to cover whole flight. Previz of the aerial shots where done in Maya using actual cartographical data. This helped us decide on lenses and plan the flight trajectory for the helicopter." explains Alex Ortoll, visual effects supervisor.

The production also used the flying cam for an aerial shot following a horse under a bridge and then coming out on the other side to reveal a wide landscape shot. "We also used it to get some really cool shots flying circles around a steam train engine at full speed,” explains Alex Ortoll.

The next challenge was the populating the mine with over 30,000 miners. The team relied heavily on MASSIVE to get this done. They did some motion capture of miners doing diverse actions. The production went to Estudios Alcine in Seville to get this done. "We capture 40 different actions of miners with picks, shovels, pushing wagons, climbing walls, etc. From each of this captures we got several different loops that where then edited in MotionBuilder and then fed into Massive. We used FBX files to move the animation from one system to the next, and from one post house to another." says Ortoll.

The core of the postproduction was done at “El Ranchito” in Madrid. Ortoll met with Felix Berges, who jumped on board as Digital FX supervisor and helped Ortoll work out most of the 3D challenges that still needed to be solved, and Sergio Garcia took care of the CG supervision.

The most challenging work of this movie was all the mine shots. We had to fill up a huge area, over a 1 mile diameter open mine, with all the miners, all the different props you can find in a 1900 mine, smoke, dust, debris and create a believable atmosphere in a shot were the only real thing filmed is the ground and also absolutely nothing is happening on it." explains Sergio Garcia.

We did several shots in which the production had to place about 30,000 miners with an almost real choreography so they don’t look like ants on a line. "We put climbers, face workers, people carrying debris, people just walking, people gathering around a crane or any type of machinery…" say Garcia.

One of the problems the team faced was due to the director wanting to show the magnitude of the mine, so he decide to use very wide lens for basically all the mine shots. "In one case we had a 20 seconds long shot with a 10 mm lens with a traveling from a close up of a basket to a wide shot of the 90 percent of the whole mine, so the movement of the camera was not easy at all and also the distortion and the lens aberration didn’t help to track the mine in one piece.” says Garcia.

In order to dress the individual miners the production photographed 250 extras one by one, placing them on a “T-stand” pose in front of a neutral background. They then projected these textures onto CG people. They also took video footage of small groups of miners doing diverse things so they could be used to texture map sprites.

Javier Gonzales Gabriel (3d artist) @ “El Ranchito” explains “The Heart of the Earth has been our first project with Massive software, so it has been both an exciting and a headache-giving experience. Every time you're new to a piece of software, you need to fit it in your pipeline, so we had to establish ways to get the mocapped animations into massive, correct or retouch them in Maya, and then back to massive. We had to build different massive brains to fit several behaviors we wanted for Riotinto's miners, and we finally needed to code some scripts and renderman shaders to get the render passes we needed automatically.”

One of the main plot points of the movie was the smoke that emanated from the mine. In order to extract the sulfuric acid, the mineral was place in enormous heaps called “teleras” that were burnt. This released enormous clouds of toxic fumes that were killing the villagers. This caused the villagers to strike against the British company that was running the mine. The director wanted this smoke to be a character on its own – “It has to be menacing”. In fact, in most scenes this smoke was on the foreground, while the background had to be filled with CG characters and set dressing (so filming the smoke on a separate pass was becoming an option). We have to see it from a moving camera and on aerial shots while we flew circles around them (…ok, so… forget the previous option). So, for those reasons and in order to keep this smoke consistent throughout the film, we decided to generate it with fluid simulations.

After testing some “off-the-shelf” and writing some proprietary software, we decided mainly on Maya Fluids. It was the quickest way to get most of the artist up to speed and get a very descent result. We tried many different types of smoke, textures, speeds, dissipations, colors, etc. Pretty much we tweaked every tweakable attribute until we got something with which the director was happy with.

All the smokes in the film were made with Maya fluids with no external plug-in. With this we got both a volumetric render and a quasi-physical simulation that provided them with a very realistic movement. The foreground “Teleras” consumed over 6GB of ram, so we had to run them individually one by one. The ones in the background could be simulated in groups of 2 and 3 so the could join at the top forming a “mushroom”. The renders were very expensive and could not be reliably processed on the render farm, so they where processed on the individual Linux workstations." Pablo Hernandez Meléndez (senior 3D artist) @ El Ranchito.

For the dust generated by the miners (footsteps, shovels, and miscellaneous dust generating activities), a totally different technique was used. The team went for sprite type particles, these where thought good enough to generate this dust.

For the big mine shot the team had to digitally recreate the atmosphere and comp in the smoke generated by the “teleras” around the upper edge of the mine."We had to achieve a very polluted atmosphere. The main problem was that it was shot on a very sunny day, all the elements of the mine where affected by the sunlight. So creating a very dense smoke “roof” for the mine would not work, since it would force us to remove any direct sunlight reference from the scene, and the result would not be satisfactory. The solution was creating a “donut-shaped-smoke-ring” that would accumulate around the upper edge of the mine (leaving clear sky at the centre of the mine) so that the sunlight could be justified.” says Javier Garcia Plaza, Digital compositor.

After much testing with many volumetric references generated in CGI through fluid simulations, and photographic references from the time in which the mine was in operation, a huge semi-circular matte painting was created and used.

To place the plumes of smoke at the rim of the mine the team used over 120 track points complemented with expressions to compensate for the lens distortion. Since the plate was shot with a wide angle lens, the sides of the frame presented a huge amount of lens distortion. As the trackers left the sides of the frame, the automatic tangential exits of the trackers would not work correctly, so the animation curve of each tracker had to be manually modified as they would exit or enter the frame.

"Apart from tracking the smoke at the edge of the mine, the smoke would accumulate at the rim of the mine. Some of this smoke had to “pour” back into the mine. So once these elements were combined we had to restore some of the miners so they wouldn’t be totally covered with smoke, a similar effect as when fog affects objects according to distance. So mates were generated to create this effect depending of the distance from camera. Sort of a manually generated Z-depth channel” explains Garcia.

The compositing of the shot had two main parts: the 3D compositing, and the environment compositing. Rendering for the second part (of about 1200 frames) took over 11 hours.

Muelle de Huelva

In the final sequence of the movie we needed to place the train and 7 wagons on top of the Pier de Huelva. This pier has become a historical landmark, and today it wouldn’t hold the weight of a real steam engine. "We had the possibility of building a fake “lightweight” train and placing it on top of the pier. But it was both dangerous and a logistical nightmare to both build it and get a shooting crew up there. So we decided to build the “train set” in Madrid and shoot the real background plates on location." explains Alex Ortoll.

Some of the wagons were mounted on springs so the production could simulate the motion of the train as it traveled down the tracks. "In most of the shots we try to frame the wagons against the blue sky, having only to reconstruct the pier below the train. The set was constructed at a height of 1.5 meters since at the end of the sequence the corpses were dumped into the ocean. This way we could use the beginning of the fall, and then cut to a wide shot of the pier where a dummy was thrown. In the latter a CG train was placed on top of the pier." explains Ortoll.

One of the biggest problems faced by the production was that the director changed the shot from night, to day, to sunset, to dawn. Hence it was shot with one lighting intention and then had to be modified digitally to fit entirely a new lighting setup.

"This sequence takes place at night on a train that sits at the top of a huge loading pier 15 meters above the sea level. The shot was filmed at two different locations, the interior and exterior of the train where shot on a set with a green screen backdrop and the pier was an actual location. There were two main problems to solve: The first was to unify both locations so to give the impression that it was all shot on the same location; the second problem was more to do with the lighting situation of the night scene. We had to justify a light source that could show everything that was happening there. A really fun job that drove us crazy for over 4 months. " Eduardo Diaz Digital Compositing Lead Artist.

Portimao (Portugal)

Some of the last sets of the movie had to be built in the beach of Portimao (South of Portugal). Due to time constraints, the location was changed to a beach near Huelva. A Victorian house was needed by the beach. Only the lower part of the set was built. The rest of the house was generated in CG. An HDRI probe was shot to get the illumination from the real location. "We were asked for just one establishing shot of that location, but on location the whole sequence was moved to the exterior of that house. Making it a constant backdrop throughout the sequence. I am very happy on how this house turned out on the big screen." concludes Alex Ortoll.

mseymour7
fx guide