T he objective of this article is to report
on the integration of improved video and related computer technology into
existing, long-accepted visibility study preparation and presentation
methodologies. The result has been an incremental extension of the types
of visual environments which can be reproduced with substantial similarity
for admission as visibility evidentiary exhibits in court.
Visibility studies - depicting what is available to be seen by a driver
(or other witness) with normal unimpaired vision under conditions
substantially similar enough to those existing at the time of the subject
incident to be relevant - have been routinely admitted in evidence in
state and federal courts since the 1960's. Proper foundational expert
testimony details basic information such as the proper viewing distance
for a life-size image and correct angular perspective; analyzes the
significance of such factors as expectancy, the average human horizontal
angle of view compared to that presented in the visibility study, and
presents a discussion of any similar factors. There have been many
articles published concerning visibility study methodology; a coordinated
set of presentations appeared in the peer-reviewed abstracts of the 11th
Meeting of the International Association of Forensic Sciences in Toronto
in 1987 at which three experts in human factors psychology, reconstruction
engineering, and engineering photography made presentations regarding the
accepted methodology for preparing and introducing visibility studies in
evidence.1,2,3
The methodology for preparing
visibility studies evolved steadily through the direct collaboration of
engineers and sci-entists in several fields, along with independent work
by numerous others. (See e.g. Klein et al.)4 A great deal of this work
related to the methods and related technology for depicting visibility
under nighttime or other reduced visibility circumstances in a manner
which would be routinely admissible as evidence in court. The methods for
acomplishing accurate nighttime films, which have resulted in routine
admissibility of such visibility studies, we redeveloped on a case-by-case
basis with engineering photographers Michael Mayda, Bruce Kayfetz, myself
and others working with human factors psychologists Dr. Albert Berg, Dr.
Slade Hulbert, Dr. Herschel Liebowitz, Dr. Kenneth Ziedman, Dr. Robert
Post, Dr. Richard Olsen, Dr. Paul Olson, Dr. Thomas Ayres, along with
lighting experts such as Michael Janoff and Eugene Farber.5,6,7
The accepted foundation method for calibrating nighttime visibility
studies involves controlled observations at the scene being compared to
exemplar 4x5 color Polaroid photographs which are annotated for observed
levels of detail, and then used as controls for producing and verifying
the level of detail depicted in the relevant areas of the final visibility
study under courtroom viewing conditions. This methodology has been
described in peer-reviewed literature by a range of engineering
photographers, reconstruction engineers, and human factors psychologists
who have been involved in developing or utilizing the technique.4,8,9,10
This represents a huge advance over the traditional practice of the past
century in which a photograph was normally admitted based on the testimony
of the photographer that "it is a true and accurate representation of what
I saw."
In the 1980's I worked with ophthalmologists to adjust visibility
studies made using film to depict measured reduced levels of visual
acuity. An example I prepared involved a motorscooter operator with
previously-measured 20/200 vision whose passenger had 20/400 vision. A
nighttime 16mm motion picture visibility study was prepared illustrating
visibility for a motorscooter operator with normal unimpaired vision
striking the side of a slowly-moving freight train crossing his path.
Working with the ophthalmologist co-expert, the image was then degraded to
depict respectively the vision of the motorscooter operator and his
passenger (using a Sealing chart which had been filmed for calibration).
This was repeated with a film which had been taken with additional warning
devices added at the railroad crossing to show what effect, if any, these
would add in warning a driver with this level of vision at night that he
was encountering dark boxcars across his path. The entire study was
routinely admitted in evidence in a California court. Modifications of
this type to visibility studies were limited in scope because of the
relatively limited alterations which could be made to film in a
controlled, quantified manner.
Motion picture film and still photographic film were the technically
most usable media for visibility studies until significant improvements in
video which became available only in the past year. This is because 16 mm
film has more than 25 times the pixels (resolution units) than does VHS
video. Recently, however, HD-video became available in camera
configurations which could be used for taking visibility studies in the
field. This format has the same pixel count as 16mm film, but appears much
"sharper" because there is no apparent grain. (This difference is
extremely significant in nighttime applications where highspeed 16mm film
has a distracting grain pattern).
The primary conclusion of this paper is that the improved video
technology (HD-Video systems) allows an extension of this
previously-practiced interaction between the visibility study preparer,
other experts and eyewitnesses to depict more accurately an extended range
of visibility conditions encountered during incidents related to
investigation or litigation.
When HD-video is being taken, a waveform monitor can be employed which
allows calibration of brightness ranges and color ranges and quantified
control in all areas of the image. Once in the computer, extremely precise
programs are available for measuring and adjusting densities, brightness,
color ranges, and other parameters overall, locally frame-byframe or
pixel-by-pixel. The level of control that is available with various
programs to adjust lighting or to depict atmospheric conditions is
unlimited. The result is that with proper foundational input and controls,
using eyewitnesses or experts for validation, conditions prevailing at an
original accident scene can be replicated more precisely than with the
previous purely-photographic tools.
Four examples of visual situations shown briefly during the oral
presentation of this paper will illustrate its objective:
1. Fog:
During daylight hours a passenger car was proceeding in dense fog
reaching to and moistening the ground. The car struck the side of a
tractor/trailer pulling forward from a stop sign across the path of the
car. Immediately after the collision the driver of the big rig, standing
at a known position on a traffic island, took a series of photographs
looking down the length of his rig with a series of signposts showing in
the photographs. The rear of his rig and certain of the signs disappeared
in the fog at ascertainable distances. The police, who arrived within
minutes, backed away from a particular sign along the path of the striking
car and measured that it disappeared in the fog at 120 ft.
HD-video was taken with a 90 degree horizontal angle of view from the
driver's position in an identical car on a sunny day following the path
leading to collision. Separately, a topographic survey of the intersection
and the approaching highway was used to create an accurate scale
"universe" of the accident scene in the computer. A three-dimensional
scale model of the particular big rig involved in the accident was built
in the computer and rendered photorealistic using photographs of the
accident vehicle. A three-dimensional "fog program" was then used to
generate the same density of fog as measured by the investigating officers
and corroborated by the accident-time photographs. The drivers-eye
HD-video was "cameramatched" frame-by-frame with the computer universe of
the accident scene using a program which photogrammetrically tracks dozens
of landmark features appearing in the video. The big rig was caused to
accelerate in the computer from the stop sign through the point of impact
as the car arrived at collision, consistent with both the reconstruction
analysis and crash tests done by various experts involved in the case. The
resulting drivers-eye visibility study showed the fog-filled scene through
the entire front windshield substantially-similarly to that measured and
photographed by witnesses minutes after the actual accident.
2. Sun Glare:
I was requested in June to prepare a visibility study for trial in a
few weeks. The issue was a driver's visibility of a pedestrian with the
setting sun on the horizon just behind him in a December accident in a
parking lot. HD-video was taken at the accident location with the June sun
still high overhead on the collision course with an exemplar pedestrian.
Hours later the setting sun was videoed at the accident altitude (on a
path adjusted at a 50 degree angle to the north) traveling at the same
speed in the same parking lot. The exemplar pedestrian again was walking
at the same respective angle to the car on the collision course. Portions
of the two videos were combined in the computer so that the buildings,
hills and other fixed features of the original accident were preserved,
but the glare on the windshield and hood, reflections on the pavement, and
the lighting on the pedestrian with the December sun position on the
horizon directly ahead of the car were accurately depicted in the final
composite. The foundation testimony for admissibility included not only
testimony from the experts preparing the visibility study, but that of the
investigating police officer who drove the same route two minutes after
the accident and wrote in her report "the glare was so strong that at 5
mph I almost struck the people standing over the body."
3. Smoke and Flames:
A wind-driven grassfire adjacent to an interstate highway was a factor
in multiple collisions and deaths. An issue was the appearance of the fire
and smoke to approaching drivers in different vehicles, at various times
over several miles. Lines-of-sight over a crest on the approach were an
issue.
HD-video was taken from several exemplar big rigs, a school bus, and a
witness truck approaching the fire/collision scene on the paths and at
speeds consistent with witness testimony. Video was also taken from each
illustrating moderate deceleration to a stop on the shoulder after topping
the last crest before reaching the fire. Video was taken from numerous
witness' positions looking at the fire area from various directions.
A three-dimensional "universe" compositing the huge fire and smoke
plume as it progressed across many acres and during some ten minutes was
prepared. (The size of the file was more than 100 gigabytes!) It was based
on an extremely high-resolution set of aerial photomaps; aerial and ground
photographs of the burned area; extensive topographic surveys, three still
photos showing the smoke and flames; photogrammetry locating the flame
front, smoke position and height; field sampling, fuel testing, computer
modeling, and a fire/smoke progress report by a fire scientist; and the
integration of information from written statement and deposition transcripts of dozens of
eyewitnesses who viewed the fire and smoke from different directions.
The elegance of the three-dimensional computer universe of the
fire/smoke is that any viewpoint can be "dialed in." The view from a
witness' position can be rendered, the resulting moving video image shown
to the witness, and the entire universe modified if necessary based on the
response. This process can be repeated with various witnesses until a
consensus universe still consistent with the physical evidence is
achieved.
Once the computer universe has been conformed to the physical evidence
and the best consensus of witness' testimony, the drivers eye HD-videos
are composited with the computer universe of the fire/smoke to show
photorealistically what it looked like to a given driver at the time he
was approaching from seven miles away and driving into and through some
quarter-mile of smoke and adjacent flames. Video-fire/smoke composites
from various witness viewpoints, along with related still "video captures"
also assist in foundation testimony for admissibility.
4. Horse Vision:
A race horse bolted while being exercised on a track and ran at full
speed into a green fence against green foliage under subdued, early
morning lighting. HD-video was taken from the horse's eye level traveling
on the path that he had been following. HD-video still footage was also
taken at measured points along the path. From these points HD-video still
footage was taken of color and grey scale charts. These were
computer-modified with a computer algorithm by an animal vision physiology
professor who has analyzed and tested equine spectral and acuity visual
response.11 His computer modifications of the HD-video color chart and
still frames provided a guide, when followed quantitatively with the
calibration devices available in the HD-video computer processing programs
and equipment, to conform the visibility study moving video to the
professor's analysis of what a horse would have seen following this path
under these lighting circumstances. Additional HD- video exhibits were
then prepared inserting, with identical adjustments for "horse vision,"
various white warning rails and other safety devices which racetrack
design experts testified should have been in place on the fence in order
to show they would have been visible to a horse.
REFERENCES:
1. Visibility Studies in Traffic Accidents. Kenneth Ziedman, Ph.D. in
Abstracts of the 11th Meeting of the I.A.F.S., Vancouver, B.C., Canada
Aug. 27, 1987, p. 329.
2. Visibility Studies, Paul Kayfetz in Abstracts of the 11th Meeting of
the I.A.F.S. (International Association of Forensic Scientists).Vancouver,
B.C., Canada Aug. 27, 1987, p. 328.
3. Motorcycle Accident Reconstruction, J. Michael Stephenson in
Abstracts of the 11th Meeting of the I.A.F.S, Vancouver B.C., Canada,
Aug. 27, 1987, p. 329.
4. Ernest Klein and Gregory Stephens, Visibility Study - Methodologies
and Reconstruction SAE Technical Paper No. 921575, Series SP-925
Automobile Safety: Present and Future Technology, Society of Automotive
Engineers, 1992.
5. Kayfetz, Paul. Driver Eye Views During Auto, Truck, and Train
Collisions and How to Get Them into Evidence. CTLA 28th Annual Convention:
Surveying the Law of the Land: Nov 9, 1989 Nov 12; San Francisco, CA (pp.
373-376).
6. Filmed Visibility Studies Routinely Admitted in Court When Properly
Prepared, by Paul Kayfetz, J.D., presented to the American Academy of
Forensic Sciences, 44th Annual Meeting, New Orleans, LA, Feb. 17-22, 1992,
p. 98.
7. Experimental Evaluation of Perception-Reaction Time Using Drive
Point of View Motion Picture Photography, Kenneth Ziedman, Ph.D. and
Michael Mayda, J.D., presented at the American Academy of Forensic
Sciences, 44th Annual Meeting, New Orleans, LA, Feb. 17-22,1992, pp.
98-99.
8. Forensic Aspects of Driver Perception and Response, Paul L. Olson,
Ph.D., Lawyers and Judges Publishing Company, Inc. Tucson, AZ, 1996 (ISBN
0-913875-22-8). pp. 146-47
9. Human Factors in the Courtroom - Accident Analysis in the Legal
World, Human Factors in Transportation - 33rd Annual Workshop (Chaired by
K. Ziedman, Ph.D.), Transportation Research Board 2000 Annual Meeting,
Wash, D.C., January 9, 2000.
10. Nighttime Photographs: Let's Look at the Forest, K. Ziedman, Ph.D.,
Paul Kayfetz, J.D., presented to the 53rd Annual Meeting of the American
Academy of Forensic Sciences, Seattle, WA, Feb. 19-24, 2000, pp.
103-04.
11. Photo Pigment Basis for Dichromatic Color Vision in the Horse. J.
Carroll, J. VerHoeve, M. Neitz, C. Murphy, J. Neitz, Journal of Vision,
2001, Vol I, pp. 80-87. Visibility, Photographic Simulations, Computer
Simulations.
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