The effects of camera resolution and distance on suspect height analysis using PhotoModeler

The purpose of this study was to examine how camera resolution and suspect-camera distance affect the accuracy and precision of suspect height estimations using PhotoModeler software. Sixteen individuals were measured and recorded standing at 15 pre-set distances on 7 security cameras, each with a different resolution setting. A height scale was used to measure each individual's height prior to recording and was also used as a reference height. Height estimates were taken in PhotoModeler by extracting video frames that were calibrated using 3D point model data obtained from a laser scan of the test site. Errors were calculated for the measurements and compared using the Kruskal-Wallis H-test, which indicated significant differences for errors among different resolutions and distances (p < 0.01). Interaction plots, however, demonstrated little difference in errors for most resolutions and positions. The accuracy and precision of height estimates began to decrease with resolutions under 960H and distances over 36.5 m.