The Munns Report - Release Number One - The Lens Analysis and Site Model
Release Date: May 15, 2009
One of my primary goals in trying to solve the problem of the Patterson-Gimlin film (and the issue of what is it that we see walking
through the scene) was to build a digital model of the site for 3D visualization research, to locate the camera positions, locate
the subject, and calculate height of the subject based on an optical analysis.
In the process of that attempt to build the digital
model, I have discovered something about the film which has been mistakenly assumed by one and all for the last 41 years, and it does
impact significantly on any analysis of the film. All assumption has been that the lens on Roger Patterson's camera was a 25mm lens,
the standard issue lens for the Kodak K-100 camera.
My analysis indicates that the camera has a 15mm lens on it instead (presumption
being a Kodak Cine Ektar 15mm lens with S mount to C mount adapter, as per the Kodak camera user's guide, because the camera requires
a companion viewfinder lens of same focal length, which Kodak only supplied for it's Cine Ektar lenses. So you can put any "C" mount
lens on the camera, but without the companion viewfinder lens, you can't see exactly what you are filming, so why bother?).
This
does impact on any height analysis of the subject, because the lens focal length is one of the numbers used in the optical formula
which defines the relationship between the subject height on film, the lens focal length, the actual subject height in real life,
and the distance from camera to subject. It effectively establishes that the subject seen in Patterson's film is over 7 feet tall,
although the exact measurement still undergoing documentation. A new scan material of the film also may allow for a finer determination. Below
you see how the lens affects apparent height of the subject being photographed, and why both the 25mm lens (presumed until now) and
the 15mm lens (that I contend is actually on the camera) affect our perception of the PG Film.
This Report Release (#1) will maintain it's focus on the site model and the lens determined by that analysis. Subsequent releases
of additional Report sections will elaborate on the subject height analysis, and other issues. A study of the PG Film footage using
a matchmove software called boujou 4.1 is also being used and has yielded a preliminary corroboration of the 15mm lens, but the documentation
on that will be in a subsequent Report segment release.
The intent of this release is to give other researchers the necessary
data to construct a similar 3D model in a 3D modeling or CAD software package, and verify the data which validates the 15mm lens specification.
In order for the data to be incorporated into other software tools, some foundation information is necessary. Once the foundation
material is completed, then the actual 3D data for objects and camera will be noted. Additionally, for some of the tree objects, image
texture maps and corresponding alpha channel mask images are included for download, to assist others in any visualization effort.
Finally, I will complete this segment with a summary of the analysis and conclusions I have drawn from it.