Gait Measurement Descriptions of Human Tracks

Search and rescue missions use a variety of tools to find missing persons, one of which can be visual tracking. Trackers detect, interpret and document information about human contact with the ground. Humans typically move on two feet at various speeds. Movement as an obligate biped leaves a series of footprints that alternates from one side to the other. This pattern of footfalls is rather simple, and the footfalls can be easily divided into descriptive dimensions. This work summarized published measurements of bipedal gait ground contact points in 70 resources. Four resource types were surveyed including 33 biomechanical gait analysis studies, 28 tracking resources, six forensic texts, and three others. This work focused on three basic measurements common to finding and interpreting footprints: (1) step/stride length, (2) straddle, and (3) pitch. This research found two ways to measure pitch, three ways to measure straddle, and seven ways to measure step and/or stride lengths. A set of recommended dimensions, presented with a diagram and a glossary, includes straddle as well as right and left measurements for pitch, step length, and stride length. One conclusion is that clear communication of the technique(s) used is more important than how to segment and measure a series of human footfalls. This paper also advocates for consistency in techniques and terminology. Whether practitioners apply tracking in search and rescue, law enforcement, military, or other applications, trackers should be consistent in the use of names or dimensions used throughout their own practice.