A comparison of image inspection modes for a visual search and rescue task

Abstract

Visual inspection and search are important tasks in many fields, including quality control, security surveillance and medical diagnosis. We investigate whether it is better to visually inspect a moving image as opposed to a series of equivalent static images using the challenging problem of locating individuals lost in a wilderness. Wilderness search and rescue may be approached with a systematic aerial search assisted by an unmanned aerial vehicle (UAV) whose camera relays the terrain below for human inspection. We investigated two presentation modes of simulated UAV video feeds. The first mimics the live video from the downward facing camera. In the second, ‘serial visual presentation’ (SVP) mode, a static image remains in view until replaced by a new image at a rate equivalent to the live video mode. We established a statistically significant improvement in the number of detected targets in the SVP mode when compared to the Moving mode. However, these improvements were accompanied by an increase in the number of incorrectly identified targets in SVP mode. UAV speed has a significant effect on target identification in both modes, presumably due to the extra time available for viewing at lower speeds. We found no significant interaction between speed and presentation mode.

Keywords:

• search and rescue
• unmanned aerial vehicles
• visual inspection
• visual search

Acknowledgements

This research was supported in part by grants from the Engineering and Physical Sciences Research Council and the Leverhulme Trust.

Notes

1. IAI Heron cruising speed: 92–127 mph (148–203 km/h); MQ-1 Predator cruising speed: 81–103 mph (130–166 km/h).