Over the years there has been a handful of images that many individuals, organizations, and media outlets have asked me to analyze. One of these is the so called Zapruder film which captured the assassination of President John F. Kennedy. Since its release, there has been much speculation as to the authenticity of this video. Here I will describe a forensic analysis applied to one aspect of the Zapruder film that, as with the Lee Harvey Oswald photo, debunks certain claims of manipulation. (WARNING: some of the images and descriptions are graphic.)
Abraham Zapruder captured the most complete documentation of the assassination of JFK. After its public release in 1975, challenges to the authenticity of the Zapruder film began to surface. The Zapruder film has been analyzed for evidence to support alternate theories of who and how many people were involved in the assassination. For example, it has been argued that on frame 317 (and neighboring frames) what appears to be a shadow on the back of JFK’s head is the result of tampering, purportedly to conceal evidence of a shot exiting through the rear of JFK’s head. This shot could only have come from a second shooter, as Oswald was positioned behind JFK.
In order to determine if the lighting and shadows in this scene are physically plausible I constructed a 3-D model of the sun’s location and the relevant scene geometry.
JFK was assassinated on November 22nd, 1963 at 18:30 (UTC) in Dealey Plaza in Dallas, TX. It is an easy matter to determine the relative position of the light at this time and place. According to the National Oceanic and Atmospheric Administration solar calculator, the sun’s azimuth and elevation at this location and date was 181.91 and 37 degrees, respectively.
We next need to know the angle between people and objects in the scene and the sun. At the time of his assassination, JFK’s car was traveling on Elm St. Shown below is a digital elevation map (DEM) obtained from airborne LiDAR (Light Detection and Ranging), courtesy of the National Geospatial Intelligence Agency. The color coding corresponds to elevation with red denoting the highest elevation and blue the lowest elevation. The long straight portion of Elm St. is 50 meters in length, and the difference in elevation across this distance is 2.75 meters, yielding an angle of 3.2 degrees. That is, JFK’s car was pitched downward as it was traveling along Elm St. As such, the road was modeled as a planar surface angled by this amount relative to horizontal.
And lastly, I constructed a 3-D model of JFK’s head and upper torso using techniques described here. Shown below is the result of putting all of these pieces together: on the left is the original video frame and on the right is a rendering of the complete 3-D model. As you can see, the shadow in the back of the head is consistent with a physical model of the lighting and scene geometry (the slight differences in the precise shape of the shadow are due to differences in the underlying 3-D shape of the hair, which are difficult to precisely model).
The shadow on the back of JFK’s head does look peculiar and I can understand why it was the source of questions and scrutiny. A physically-based 3-D model of this scene, however, reveals that the shadow is plausible. In general, the construction of 3-D models of lighting and geometry, although somewhat time consuming, can be remarkably powerful in helping to reason about an image.