Determining the Vertical Line from Zapruder in Willis 5
Determining to which Zapruder frame the Willis slide corresponds is made much
easier by Willis appearing in the Zapruder film, Zapruder
being visible in the Willis slide, and the motorcade passing between them. This allows the
construction of a plane between the
center of the two cameras which appears in the images as a line because it is
being viewed edge on. The plane does not have to be vertical to make a
comparison. It just has to be the same plane in each image but it is generally easier to
determine the vertical plane. The Willis slide has the Dealey Plaza pergola in
the background which has a number of vertical features. Parallel lines converge
to a "vanishing point" in a photo unless they are perpendicular to the direction
the camera is pointed. With vertical lines this is only true if the camera
is pointed horizontally. Willis was pointing the camera slightly downward.
In this case lines that are vertical in the world point in different directions
in different parts of the image and only the (world) vertical line that passes
through the center of the image is vertical in the image. (After
leveling the image) We need to draw a vertical line, representing a vertical
plane, from Zapruder's camera. This can be done by determining the vanishing
point from vertical features in the image and then drawing a line from
Zapruder's camera to the vanishing point. The image on the upper right shows
the (true) vertical lines from the references to the vanishing point in black
and the vertical computed for Zapruder in red. The vanishing
point lies far below the image as shown in the drawing on the left.
Remember, the red line is really a vertical plane passing through the center of
Zapruder's and Willis' cameras. The plane passes through the left edge of
Clint Hill (sorry, Clint) standing on the running board so we can use this
information to determine the corresponding
Zapruder frame. It really does not matter how the image is rotated in 2d
since the lines rotate with the image, but I think a leveled picture looks
better and the Zapruder frames are level so I provided a leveled image with just
the vertical from Zapruder drawn. (lower right)