Camera Data
Camera Positions - Note that the camera positions start at C3. C1 and C2 are for the beginning sequence of
the PGF, and as work is still underway to connect the beginning sequence to the main site area, this will be shown in a later segment
of the report. So C3 is the first camera position showing the main log, the big tree in the background, and such. It is Frame 205
in the PG Film sequence.
Camera/BG image code is as follows:
TMR (The Munns Report)
PGF (Patterson Gimlin Film)
"C" plus number
- The camera position on my site map
bg - indicates background image for comparison
"F" plus number - Actual film frame number for reference.
Verification
Documents
Each link below goes to a image with three panels validating that camera position and the site model alignment
to the PG Film. In each panel, the top image is the PG Film frame, set up as a potential background image for other researchers to
test. You will need to crop that top panel to 800 x 600 for use as a background image in an animation software application.
In
each panel, the three images are: A) the background image, a PGF frame B) my render of the site model
with the background image in place, to compare alignment of model and film C) the model objects alone, no background
image, to clearly see the objects. The Site Model Data Form has scale, position, and rotation coordinates for every object as well
as position and rotation coordinates for each camera position. A Chart grading all the object matches is HERE.
The above link will give you the actual Site Model Data Sheet which contains all the
coordinate information on all site model objects ( dimension, position, and rotation) as well as the coordinates (position and rotation)
for all seven camera positions, so you may test this model in a 3D visualization software application. This document will be considered
my proof that the model and the camera positions and lens specification (a 15mm lens) are correct.
Please Note that there are
two versions of this chart, because my 3D application has used objects called symmetrical lattices as the five center trees, while
many other 3D applications will use simple image planes for those trees. Bryce loads the symmetrical lattice into the workspace laying
flat (one mesh up, its mirror mesh down). So when it is used to make a tree, I must rotate the object -90 degrees to turn it upright.
If you use an image plane created already in an X & Y orientation, upright, then that -90 degree rotation is not necessary. So
in the second form (Noted "For X, Y Image Plane Trees") the rotation on C1 to C5 are 90 degrees different from my Bryce coordinates.
An Image plane also has only two dimensions, so you will see only X and Y size coordinates.
I invite other researchers to test or check my data independently. If you feel that another solution of object
arrangements and/or camera positions and/or lens angles will produce a result as well, or better, and thus re-butt my contention that
this is the correct solution, please use the following blank form to note your data for object and camera coordinates and either post
in a forum or e-mail to me, and I will be pleased to test the data you provide, and publish the results to compare with my results
herein.
Comparing Other Site photos
Aside from the actual site images contained in the PG Film itself, there were other photos of the Bluff
Creek site taken in subsequent years by other investigators. Byrne and Dahinden visited the site and took pictures which are available
to researchers.
Comparing the digital site model of mine to these photos is a different procedure, because we do not know the
camera, lens, or original film image format, whether the image we have has been cropped, etc. But if the location of the camera can
be found, and a digital picture (a render) of the digital model is made with simply a wider field of view than the trees and objects
seen in the research photo, we can test to see if the digital trees and objects align with the photo trees and objects, in a position
and proportional size comparison. If there is an alignment, this lends further credibility to the accuracy of the digital model.
For
the two photos compared, I have included a separate data sheet listing the camera position and rotation coordinates used to produce
the digital render. These coordinates give us a fine proximate camera position for the people who took these photos on the real site.
In the digital renders, there are additional gray cylinders for trees in the north rim section of the site. These trees have
not yet been fixed in a final position, and have not yet been identified. They are simply additional trees that the continuing effort
will try to confirm location of, in the final site model and diagram which will be released in subsequent months with the final report
release.
About the Photogrammetry Process
Introduction - A sophisticated technique, called stereophotogrammetry makes it possible
to estimate the three-dimensional coordinates of points on an object seen in photographs. These are determined by measurements made
in two or more photographic images taken from different positions. Common points are identified on each image. A line of sight (or
ray) can be constructed from the camera location to the point on the object. It is the intersection of these rays, by triangulation,
that determines the three-dimensional location of the point.
Photogrammetry is used in different fields, such as topographic
mapping, architecture, engineering, manufacturing, police investigation, and geology, as well as by archaeologists to quickly produce
plans of large or complex sites. It is also used to combine live action film footage with computer generated effects in movies.
Algorithms
for photogrammetry typically express the problem as that of minimizing the sum of the squares of a set of errors.
For more explanation
of the process, go HERE