In reproducing the famed spider walk from THE EXORCIST for the prequel, EXORCIST: THE BEGINNING
, Pixel Magic
of Toluca Lake, California (www.pixelmagicfx.com
), called on the 3D scanning expertise of Eyetronics
I used Eyetronics in the past and was impressed with their technical skill, reliability and the portability of their scanning equipment, explained visual effects supervisor Ariel Shaw. They were able to send technicians from their European office to the set in Rome for scanning, allowing us to meet our tight production deadlines without having to disrupt filming schedules.
The Eyetronics technicians captured facial scans of Father Merrin, played by Stellen Skarsgard, and Dr. Sarah Novack, played by Izabella Scorupco. They also captured full-body scans of Sarah. Both the facial and full-body scans were captured with Eyetronics ShapeCam system, a digital camera mounted on a light-weight frame with a special built-in flash that projects a fine grid onto the object being scanned. The scan data is collected with two quick pictures one for 3D data and the second for texture data. After the capture session, Shaw determined that only scan data from Sarah was needed for the vfx shots. The scans were processed at Eyetronics facility and the resulting 3D face and full-body models were output as both high- and low-resolution Alias Maya files for animators at Pixel Magic.
Eyetronics ability to provide both low- and high-resolution models saved us a great deal of time, added Mike Hardison, CG supervisor with Pixel Magic. Normally wed have to re-build a high-rez scan to make it work with the other geometries of the model. The lower resolution meshes also afforded the ability to work with varying levels of complexity.
Aside from the time-saving benefits of the Eytronics scans, Hardison also noted the accuracy and detailed texture mapping. There are subtle deviations especially in the face that are very hard to copy. Even if you get all of the geometry right, you can resemble the person, but its just not right. Scan data ensures that you have an accurate representation with all the correct bone structure and underlying geometry.
The facial scan data was used for two scenes in the film. The first comes after Father Merrin throws Sarah against a cave wall in an effort to rid her of the demon that has possessed her. She then spider walks across the wall, referencing a scene from the original EXORCIST in which Regan spider walks down a set of stairs. Both shots in the spider walk sequence were fully computer-generated. All elements from the rock wall surface to Sarahs body to the lighting were created by Pixel Magic in Maya and NewTeks LightWave. The directors on the film considered compositing between live-action and CG elements, but making the transitions seamless proved to be too difficult, including the interaction between filmed footage of Scorupcos stunt double and the CG rock face. Creating the shot entirely in CG gave us more control over all of the elements, said Pixel Magics vfx producer, George Macri. We used the Eyetronics texture maps as a reference when we created the final textures for Sarah to ensure that they would hold up with the camera zooms we used for the scenes.
In a later scene, the still-possessed Sarah is hanging from a cross by her feet, and in another feat of physical impossibility, she rights herself by bending backwards until her hands reach her feet. She then jumps down from the cross. To achieve the eerie effect, animators at Pixel Magic used Eyetronics full-body scan data of Scorupco to create a CG body that was composited with live-action head and hair. The combination required a great deal of morphing and match-moving to create a final sequence the animators and directors were happy with.
We tried to composite several different live-action shots of Scorupcos stunt double, but couldnt achieve the look we wanted, especially when the character lifts her arms over her head, said Ray McIntyre Jr., vfx supervisor with Pixel Magic. And when we tried the all-CG approach, the neckline and upper torso of the dress didnt match well through the entire movement. In the end, the combination of live-action and CG made the look more realistic.
The cross dismount sequence was composited into the final scene with a live-action background. Pixel Magic replicated the lighting from the filmed sequence in the CG elements. As with the spider walk scenes, they used Syflex Cloth Simulator to create movement in the CG dress.
Eyetronics creates 3D scanning solutions for the entertainment industry. For more information visit www.eyetronics.com