By Karen Moltenbrey
Four decades after the tragedy in Dallas, it's still one of the most enduring questions of our time. Despite the findings of two major governmental investigations, many Americans today still doubt that Lee Harvey Oswald acted alone, if at all. A key piece of evidence that is used to support both sides of the controversy is an 8mm home movie of the shooting captured by local resident Abraham Zapruder.
Forty years later, freelance computer animator Dale Myers definitively answered the lingering question during an ABC special marking the anniversary of the assassination. Using state-of-the-art film and computer graphics tools and techniques, Myers explained how he built an exact 3D re-creation of the scene as captured by Zapruder that precisely matches that archived film frame for frame. Then, tracing the fatal bullet's trajectory within this three-dimensional space, he showed that the shot aligns to the 6th-floor window of the Texas School Book Depository—the exact location from which Oswald was determined to have been—and not to the grassy knoll where some speculate that a second gunman had been.
"It only happened one way and because of all the photographs that exist, we were able to visually re-create that one way based on fact from the filmed record," Myers says.
Long ago, Myers also believed in the popular theory that Oswald was framed or had an accomplice—and that a number of people were involved in the subsequent cover-up. In the mid-1970s, he viewed a poor-quality bootleg copy of the Zapruder film, which had not yet been seen by the general public, and began his own investigation when the film showed Kennedy's head lurching backward after he was struck, indicating the bullet had entered from the front, not from the direction of the depository.
After seeing this, Myers began thoroughly researching the assassination. And 10 years ago, he decided to meld his personal interest in the case with his skills as a freelance animator by re-creating the event in 3D by using the first version of NewTek's LightWave 3D. The models were simplistic, but they were accurately built and animated. And they showed that the conspiracy theory was wrong and that Oswald had fired the fatal shot.
|Animator Dale Myers re-created Abraham Zapruder's film of the Kennedy shooting frame by frame inside LightWave, which resulted in an accurate three-dimensional view of the scene. Images ©2003 Dale K. Myers.
"Any 2D photograph contains the necessary 3D geometry, or the spatial relationships of the objects in its field of view," Myers explains. "Therefore, I knew I would be able to build a three-dimensional model of Dealey Plaza, the car, and the occupants. And because we know where Zapruder was standing, I could create a virtual camera and align his film with the three-dimensional model, in essence, putting his film back into its original 3D form."
As the anniversary of the assassination approached, a friend working with ABC suggested that Myers' work could offer a fresh view for the network's planned broadcast. Meanwhile, Myers had been contemplating a digital face-lift for the entire animation, which he still plans to complete. Until then, he licensed six and a half minutes of revamped CG to ABC, including the crucial moments when President Kennedy and fellow passenger Texas Governor John Connally were shot.
Initially, Myers thought that he could just swap out the generic humanoid characters for realistic models and replace the hybrid car (which contained accurate dimensions) with a detailed model of a 1961 Lincoln. "But I soon realized that the modeling and animation methods had evolved greatly," he says, "requiring me to redo the entire sequence from the ground up."
First, Myers collected a series of photographs and hired a sculptor to craft life-size busts of Kennedy and Connally, from which he made plaster castings. Using Immersion's MicroScribe 3D digitizing arm, which captured the dimensions of the busts, Myers created a highly detailed virtual replica of each. "However, ABC and I both agreed to pull back on the realism by eliminating the fibrous hair, the facial details, and the super-real skin shaders so the models appeared mannequin-like, eliminating the shock factor and providing a scientific appearance to the animation," he says.
To create the bodies and the clothing, Myers adapted Viewpoint models (now offered through Digimation), and added expressions, or mathematical equations, in LightWave 7.5 for accurate cloth simulation—which is vital in determining a bullet's trajectory in the frame where Connally is shot. Myers built the car from NURBS in LightWave, using body-draft information published in the two governmental reports. And to re-create the area, he and his technical assistant, Jon Tindall, used more than 500 of their own plaza photos and a great deal of other information about the event and the location, including survey maps and actual blueprints of the book depository.
From the photos, Tindall generated environmental texture maps within Adobe Systems' Photoshop. One of the biggest challenges was re-creating the foliage, which included 16 trees and numerous bushes. To accomplish this, the animators purchased a detailed (40mb) oak tree model. But because of its size, Tindall initially could load only five tree models, despite using a 3DBoxx workstation from Boxx Technologies with 4gb of RAM, dual Intel Xeon 3.06 processors, and a 3Dlabs Wildcat4 7210 graphics board.
"Foliage makes great-looking CG," claims Myers. "But it's memory-intensive. So if you have an extensive scene in terms of object size, you usually pull back on the foliage. Yet I wanted this outdoor scene to look terrific, which required Tindall to find a way to add all 16 trees and make each look as good as the 40mb model."
Tindall's solution was to cull the model by eliminating polygonally described branches inside the thick canopy and changing the transparency maps of the leaves to a clip map, which is more efficient to render. As a result, he was able to reduce each tree to 500kb without suffering a perceivable loss in quality, buying additional memory for adding detail to the buildings and other objects in the scenes.
After building the models and the background, Myers worked frame by frame inside LightWave, superimposing the models onto their counterparts from the Zapruder film to achieve a virtual replica of the scene, complete with a virtual camera synchronized to the actual camera. To do this, he aligned and matched the speed of the Zapruder camera pan, resulting in a digital handheld view of the empty road. He then added a second layer that places the moving car into the scene, again matching the precise motion from the film.
|Using many references, including personal photos, the animators re-created Dealey Plaza (top), including the foliage. This CG still (bottom) shows the president's car passing through the plaza just moments before the shooting.
Finally, Myers integrated the vehicle's occupants, choosing to add only Kennedy and Connally for visual clarity and to streamline the modeling/animation process. To determine the precise positions of the two men in the car, he enlarged the portion of the film showing both in center frame during the shooting.
"Once we did all that, we had a frame-for-frame digital match of the Zapruder film," says Myers. "But what many people don't realize is that when you bring a copy of the film into the computer, you have to convert it from one format to another, from a video rectangular-pixel world to a CG square-pixel world or vice versa. That's why people who are unfamiliar with the mediums have difficulty replicating the results on their own."
As Myers explains, Zapruder's silent 8mm color record—the only known film of the entire assassination—was available in a digital video format. When that was imported into the computer, the aspect ratio difference between the digital video and the actual film posed problems in aligning the film with the computer models. So Myers converted the digital video back into its original film aspect ratio using specifications that were standard for 8mm film from the period to achieve an exact conversion.
After the alignment was completed, the animation, which was keyframed to match Zapruder's original 18.3 frames per second (fps) film, was "rephotographed" at 30 fps in a digital video format. Although Myers used a partly rendered/partly wireframe CG animation of the event running at Zapruder's original frame rate of 18.3 fps to show the events just prior to the shooting, when the car emerges from behind a sign blocking the view—at the moment Kennedy and Connally are hit—the models turn into solids. At this point, Myers rendered the animation at today's 30 fps standard, and all the key positions were automatically adjusted inside LightWave. As a result of this process, the imagery was much smoother and clearer than it was in the Zapruder version, revealing details that were present all along but were difficult to see.
During the broadcast, Myers pointed to the Zapruder film showing the limousine as it just completed its turn onto Elm Street. Frame 133, he notes, is the first in which the president can be seen, and Frame 160 is when the first shot occurs. Apparently that bullet missed the intended target, as the governor is shown turning sharply to his right in the direction of what he later said sounded like a high-powered rifle discharge. A few frames later, the car disappears, and then in Frame 223, it emerges from behind a freeway sign with Connally coming into view first, seemingly uninjured.
"You can see his white shirt, jacket, and a gray area where the tie is," Myers pointed out. "Then something happens between Frame 223 and 224. The jacket changes shape; it pops out, or folds out, a little bit. In fact, the bullet has just struck him in the right side of his back and emerged from [his chest]. In the next frame, the president comes out from behind the sign, and we can see a kind of anguished look on his face. His hands immediately go up toward his throat in a guarded manner. Both men are acting simultaneously."
|President Kennedy and Governor Connally were positioned inside the vehicle (left) as they were in the Zapruder film. Using a wireframe view (above), the animator traced the bullet's trajectory back to Oswald's position in the book depository windo
So, if both were hit from behind with the same bullet, where did it come from? Using the men's body positions and locations of their wounds, Myers isolated the source of the shot by connecting Connally's entrance wound to the exit point from the president's throat, then projected that line rearward to its source—the sniper's nest in the depository.
In contrast to when Myers first re-created the event, this time he already knew the results that would answer one of the biggest mysteries of the 20th century. "Because I had better-quality imagery from which to work, some of the numbers [calculations and measurements] were slightly different," he says. "But like any valid scientific experiment, I was able to repeat the process and come to the same conclusion. And the animation shows that there wasn't a magic bullet at all," he says, referring to the belief that an inconceivable ricochet was necessary in order for both men to be struck in succession.
"It's not even a single-bullet theory in my opinion," Myers adds. "It's a single-bullet fact proven by the animation."
Karen Moltenbrey is a senior technical editor at Computer Graphics World.
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