A study was conducted to assess the relative accuracy of two
measurement techniques commonly used for vehicle measurements in
damaged-based accident reconstruction. The traditional technique of
hands-on measurement was compared with the use of photogrammetry
for measurement of targeted damaged vehicles. Three undamaged
vehicles were subjected to 4 impacts, resulting in 4 damaged areas
(two front, one side and one rear). The study's intent was only
to examine the accuracy of each measurement technique. The
influence of other confounding independent variables such as
selection of measurement location on the vehicle, reference line
location, and definitions of what constitutes "damage,"
etc., were controlled for and minimized by using predefined
measurement points on the vehicles and prescribed station
lines.
The points on each vehicle were measured using both techniques,
and compared to baseline reference measurements obtained via a
TOPCON GPT-7005i prismless imaging total station. PhotoModeler was
employed as the photogrammetry technique, and photographs of the
post-impact vehicles were obtained using several different cameras
and photographers, including an adjuster with no formal training or
instruction in photographing for photogrammetric analysis. Hands-on
measurements were obtained via two groups of qualified
professionals in the field of accident reconstruction, with access
to both the vehicles and traditional measuring equipment such as
tape measures, crush jig and plumb bobs.
The results found that both methods effectively measured the
vehicle points, with a mean difference between the baseline and
hands-on measurements of 0.6 ± 1.4 cm, and a mean difference
between the baseline and photogrammetry measurements of 0.1 ± 1.0
cm. The accuracy of the photogrammetry method was found to be
slightly greater than that for hands-on physical measurements. The
results indicated that both physical inspection of a damaged
vehicle and photogrammetric analysis from photographs are suitably
accurate techniques for vehicle damage measurement, and in some
cases the photogrammetric analysis may even yield superior
results.