Ever since the assassination of President Kennedy, numerous theories have circulated claiming that Lee Harvey Oswald, the accused assassin, acted as part of a larger criminal conspiracy. It has been suggested, for example, that incriminating photographs of Oswald were manipulated and hence evidence of a broader plot. I have never been particularly interested in these conspiracy theories. I do, however, like that at least one aspect of the theory was testable – were the shadows in the Oswald backyard photo physically plausible or not?
A portion of the argument for photo tampering goes something like this. Consider the shadow cast from Oswald’s body onto the ground. The orientation and length of the shadow suggest that the sun is to Oswald’s left and relatively low on the horizon. The long straight shadow under Oswald’s nose, however, suggests that the sun is directly above him. These seemingly incongruous shadows have led to speculation that Oswald’s head was pasted into the scene. In fact, Oswald himself claimed that the photo was a fake and had been altered to falsely implicate him.
I thought that there was a chance that the photo was fake because it does seem at first glance that the shadows in this photo are inconsistent with one another. I also know, however, that our visual system can be spectacularly bad at judging such things as lighting and shadows in a photo.
In order to reason about the shadows in this scene we need a three dimensional model of the scene (Oswald’s head/body and the ground plane) and the three dimensional location of the sun. In general, determining three dimensional information from a single two dimensional image is an under-determined and difficult problem. Estimating three-dimensional models of a person’s head, however, is relatively easy because of the somewhat constrained and well understood geometry of human heads.
- Lee Harvey Oswald’s Original Coffin Goes on Auction Block (lawprofessors.typepad.com)
- Kennedy assassination investigator Gaeton Fonzi dies in Manalapan at 76 (miamiherald.com)
- The Kennedy Assassinations (lewrockwell.com)
- Who Was Lee Harvey Oswald? (Full Version: Playlist) (undergrounddocumentaries.com)