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AN AUTOMATED 3D MOTION ANALYSIS SYSTEM
FOR DIGITIZED HIGH SPEED FILM
Peter Axelsson
Department of Photogrammetry Royal Institute of Technology
100 44 STOCKHOLM, Sweden
e-mail pax@fmi.kth.se
ABSTRACT
A 3D motion analysis module was developed for an
existing 2D high speed system. A high level of
automatization is required, as is a user interface for
non-specialists in photogrammetry. A short and fast
dynamic process is recorded with high speed
photographing using two or more film cameras, and
the film is digitized in a film scanner. After point
identification in the first image the points are
automatically tracked, measured and analyzed in the
rest of the film sequence. A high flexibility ensures
the system to handle different situations concerning
target calibration, self calibration using bundle
adjustment and point determination depending on
the environment and point configuration. A
commercial implementation for the car industry is
demonstrated.
Key words: 3D, tracking, high speed, motion analysis,
calibration, bundle adjustment
1. BACKGROUND
A high speed 2D motion analysis system was to be
extended with a 3D module for a more general and
accurate evaluation motion in fast dynamic
processes. The existing system, TrackEye (Product
information), is a general motion analysis system
with high flexibility concerning the image input. The
3D module was of special interest for high speed
digitized film sequences of car crashes in controlled
environments. A typical example is a car crashing
against a wall, fig 1, or studies of the effect on the
human body, fig 2.
fig1 Controlled car crash
fig2 Sledge for studies of the effect on the body
A system for 3D calculations from measurements in
high speed films will be encountered with several
problems not found in more traditional
photogrammetry. These problem will be of different
types, ranging from a different kind of camera
geometry to the large amount of data in movement
analysis. The system must also be highly automated
to be able to run in an industrial environment with
as few as possible interactions with an operator. In
the discussed system the automation level is set at a
very high level during the whole process, starting
with automated measurements in the digitized
image, calibration of various types, bundle
adjustment with self calibration and 3D calculations
of object points.
2. THE EXISTING SYSTEM
The Video and Cine Film Analysis system, TrackEye,
is an fully interactive system, menu driven and with
a high level of automation of the process if wanted,
fig 3. The system is PC controlled with a special hard
ware unit for the image handling and processing. A
film scanner is used for converting the high speed
film to digital images.
Color monitor
768 x 512
Camera TrackEye Software
Recording
Tracking
Analysis
——— =
Image Work Station
Video Recorder
r=
[^
=] Keyboard Mouse
Film Scanner Videodisc
fig3 — TrackEye motion analysis system
