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Going to the 'Sahara' with Cinesite and Double Negative

Alain Bielik travels into the world of Sahara, where Cinesite and Double Negative were enlisted to create the fantastic vfx.

Sahara is filled with such old fashioned, adventure movie traditions as realistic characters, exotic locations and non-stop action. Courtesy of Double Negative. All images © 2005 Paramount Pictures.

Just when you thought that all modern action heroes had to be superheroes, Paramount comes back to the old fashioned adventure movie tradition with realistic characters, exotic locations and non-stop action. Adapted from Clive Cusslers best-selling novel, Sahara is the second big screen adventure of treasure hunter and trouble seeker Dirk Pitt (Matthew McConaughey). The characters first film appearance hardly left an impression on anyone as Raise the Titanic failed to raise a dime at the box office in 1980, but Paramount is hoping that Sahara will be the first installment on a new and refreshing franchise. In this adventure, Pitt embarks on a treasure hunt to find a missing Civil War-era Ironclad Battleship. His investigation leads him to West Africa where a nuclear waste disposal plant threatens the whole planets ecosystem.

Battle Scene

The movie opens with a major effects sequence set at night in Richmond, Virginia, during the Civil War. Engulfed in flames, the town is under heavy fire from Union troops from an Ironclad Battleship). The ship was built as a 120-foot full-size floating replica by physical effects coordinator Dominic Tuohy and Cinesites Effects Associates on a lake nearby Shepperton Studios in England. The surrounding British countryside was later replaced by a digital environment created at Double Negative, London, which produced 195 shots for the movie. We first conducted extensive research into the architecture and look of the period, recalls in-house visual effects supervisor Frazer Churchill. After a lot of effort, we managed to get hold of a book that featured drawings and photographs of Richmond in the 1860s. Using Photoshop, matte-painter Neil Miller then created a digital Richmond based on this reference material and on the town as it is today. In reality, we had to completely redesign the city in order to match the directors framing and aesthetic requirements. For example, we added a hill where there was none and repositioned the citys landmarks to better suit the shots. Featuring a crane move from the city in the background to the battleship in the foreground, the master shot of the battle sequence includes more than 60 layers and lasts some 1,000 frames.

Cinesite built a full-size Ironclad Battleship on a lake near Shepperton Studios in England. The surrounding British countryside was later digitally created at Double Negative. Courtesy of Cinesite.

The destruction of the city was created by a combination of live pyrotechnic effects and CG animation. Dominic Tuohy rigged a Richmond street set to generate huge flames with propane gas. These fire elements were combined with flame elements extracted from Double Negatives own library and added to the matte painting to create an end of the world feel to the scene. The company also developed digital smoke and used CG dynamics to create collapsing buildings. The CGI was produced in Maya under Ryan Cooks supervision, rendered in RenderMan and composited in Shake.

One of the specific aspects of the sequence was the constant firing of cannonballs, both from the battleship and the city. The cannonballs were created in CG and integrated into the scene, explains Churchill. We also developed a specific smoke generator to simulate the spinning effect of the fuse that is attached to each cannonball. Director Breck Eisner was very keen on this corkscrew effect. The sequence included a shot in which the camera pans from the shore to the ship in the foreground and follows a cannonball bouncing off the hull and blowing up in the air. The pan was shot live with the camera operator framing an imaginary cannonball. We then took the plate, added cannon muzzle flashes in the background, animated a cannonball to bounce off the ship and integrated an explosion shot separately. In order to create the proper interactive light on the ship during the explosion, we shot a second pass with director of photography Seamus McGarvey lighting the set to approximate a fiery explosion. The two passes were later combined in Shake to create a realistic explosion with interactive light.

A digital Huey was built and animated in Maya for a sequence in which a helicopter chases a car in the desert. Courtesy of Double Negative.

Digital Stunts

Later on in the movie, Pitt ends up stranded in the Egyptian desert. He demonstrates his resourcefulness by scratch-building a land yacht out of an airplane wreck. The shots featuring the vehicle in action were tackled by Double Negative. The art department had built a full-size land yacht on top of a go-cart, comments Churchill. The two elements were connected by a rig that allowed the replica to tilt over, just like a real land yacht would do. In order to create the illusion that the vehicle was wind-powered, we had to remove the go-cart, its driver and the rig itself from each frame. We also added a dust trail generated with Maya dynamics. One of the major undertakings in this sequence and in the rest of the movie was the digital removal of any unwanted elements in the frame. Since a large part of the movie was shot in the desert with hundreds of extras, many horses, 50 tanks and a very large crew, the locations quickly ended up as a complete mess with tracks and footprints all over the place. We had to replace the whole desert floor by a computer-generated environment. A massive rotoscoping effort was then undertaken to integrate the new background behind the live action. CG dust clouds were added in to complete the shots.

Double Negative also tackled a sequence involving a helicopter chasing a car in the desert. A digital Huey was built and animated in Maya for shots in which the aircraft had to fly through major explosions and dust clouds. Working from empty aerial background plates, Churchills crew built the shots by layering in real smoke and explosions, shot separately, while the CG Huey was animated to fly in this dangerous environment. We considered adding smoke and explosions to a clean plate of a real aircraft, but CG animation allowed us to orchestrate some very specific moves that the director wanted, observes Churchill. It also produced a very realistic interaction between the rotor blades and the smoke, for which we used CG dynamics. The main challenge here was to be able to cut seamlessly from the real helicopter to the digital version and back.

The huge solar plant located in the middle of the desert serves as a major set piece of the film. The sequences 145 effects shots were awarded to Cinesite. Courtesy of Cinesite.

A Pixel-Made Solar Plant

A major part of the action focuses on the huge solar plant set in the middle of the desert. In the storyline, the plant is being used to incinerate toxic waste that has become the source of a major health hazard. The sequences 145 effects shots were awarded to Cinesite, with Royston Willcocks supervising the 3D work and David Sewell coordinating the 2D effort. The plant was totally fabricated in the computer, notes Willcocks. The only section that was built as a full-size set was the helipad on top of the burn tower. The set was about three stories high but we digitally extended it to place it 350 feet above the ground. The plant was designed by the art department and combined architectural elements from several actual solar plants. We built it in Maya using hundreds of reference photographs and measurements provided by the production. We also replicated the handful of life-size solar panels that the special effects unit had built for principal photography. The real mirrors measured 20 feet by 10 feet and were carefully reproduced in digital form. We then wrote a specific code that allowed us to include slight variations in the positioning of these 8,000 mirrors all around the central tower. It created a realistic, random look to the mirrors field.

The plant was totally fabricated in the computer except for the helipad on top of the burn tower, which was a full-size set. Courtesy of Cinesite.

While the plant itself was completely fabricated, the environment was built by stitching together photographs of the Moroccan desert taken in a 360° arc by overall visual effects supervisor Mara Bryan (Die Another Day) from a helicopter. Mara shot with several focal lengths in order to give us the opportunity to select the most appropriate one for each shot, explains Sewell. Once the 3D dome had been completed, we imported it into the Maya landscape of the plant. It ensured that the reflections on the mirrors would be realistic from every camera angle. For shots featuring the solar plant up close, Cinesite used 2D matte-paintings in which more details could be incorporated. The Maya files were rendered in RenderMan and composited with Shake.

Once the plant and its environment were completed, it appeared that the resulting imagery lacked details. For shots looking down from the top of the tower, it was impossible to see if we were 100 feet or 350 feet up, adds Sewell. The solar panels were too abstract to give a sense of scale. So, we ended up building a lot of extra set elements that the viewer could relate to. We added electrical cables, boxes, trolleys, tracks, and many other 3D elements scattered around. Right away, it gave the scenery a real sense of scale.

The 3D dome was imported into the Maya landscape that was built by stitching together photographs of the Moroccan desert. Courtesy of Cinesite.

Let the Sunshine In

During a fight sequence at the top of the tower, the plant is activated and all solar panels tilt to reflect the sun up to the burn tower. To simulate the effect of 8,000 combined light sources, Sewell employed several techniques: We had some bluescreen plates of the actors, but also many shots from the platform set, which required specific keying and grading techniques. The plates had been photographed with the full-size mirrors actually illuminating the set, but it was far from enough to simulate 8,000 light sources. Using inferno, we carefully overexposed the shots, added a lot of flashes and lens flares, and integrated an intense heat wave. It was all done on a shot per shot basis. The problem was that the whole movie was going to be digitally graded. Thus, we had to go through a long trial and error process to come up with a look that allowed the digital grading. If the image was too bright, it could no longer be graded. If it was too dark, it didnt have any impact. It took quite some time to find the right balance.

For the same sequence, Double Negative created the powerful energy beam that is generated in the burn chamber. The beam had to feel dangerous and out of control, says Churchill, and its look needed to be grounded in reality, fiery and lethal, yet visually different and more interesting than fire. We researched footage of blast furnaces and explosions and toyed with the idea of flames feeling like fluid. Breck liked the idea and this is the direction the development of the effect ultimately took. The energy beam was realized by John Kilshaw and Tom Rolfe using fluid simulations and Maya dynamics.

For all involved, Sahara marked a welcome return to traditional adventure movies, a genre that has been recently neglected due to superhero frenzy. The movie features almost 400 effects shots, but they all support the action, concludes Churchill. When watching the movie, people shouldnt be even aware that there are any effects in it

Alain Bielik is the founder and special effects editor of renowned effects magazine S.F.X, published in France since 1991. He also contributes to various French publications and occasionally to Cinéfex. He recently organized a major special effects exhibition that opened February 20th at the Musée International de la Miniature in Lyon, France. Displays include original models and creatures from 2010 Odyssey Two, Independence Day, Ghostbusters, Cliffhanger, Alien Vs. Predator, Alien3, Pitch Black and many more. The exhibition will run until Aug. 31.