G. P. Bailey
R. K. Harle
University of Cambridge, United Kingdom
Stereo Vision, Ground Truth, Wearable Sensors, In-Field Assessment, Running, Gait, Foot Kinematics, Continuous Sensing.
Computer Systems in Sports
Multimedia and Information Technology
Sport Science Research and Technology
Sport Statistics and Analyses
In-field validation of the accuracy of wearable sensors is desirable since algorithms that perform well in a
laboratory setting may not perform as well in real-world use. However, the use cases can be challenging. For
example, a foot worn wearable designed to measure foot trajectory should expect to be used in a variety of scenarios
ranging from straightforward (running track) to challenging (a woodland area with many undulations).
Typically the more challenging the scenario the more difficult it is to get ground truth with conventional
systems. We describe a low-cost, highly-portable, point tracking system that can be used where space and
infrastructure is limited. The system is built around a pair of commodity video cameras in a stereo setup.
We demonstrate how to configure the cameras, a novel technique to approximate shutter synchronisation to
sub-frame interval, and we benchmark the system indoors against gold-standard motion capture systems. For
a runner 3 m from the cameras wer
e able to recover their foot trajectory with a mean spatial deviation of