Thermal infrared target detection and tracking has challenging and useful applications outside of military scenarios. A digital image processing technique is described for the detection and tracking of free flying bats. Uncalibrated video-rate thermal imagery from a stationary FPA micro-bolometric IR imager is captured on 8-bit digital media. Sequential frames are differenced to remove stationary clutter, and thresholded to select pixels outside of the central distribution of differenced pixel values (both positive and negative). Moving objects then appear as pairs of pixel clusters of differing contrast polarity. For the typical case of a warm bat against a cool background, a pixel cluster exceeding the positive threshold indicates a target location in the current frame and corresponding pixel cluster below the negative threshold indicates the target’s location in the previous frame. These location pairs define a motion vector that is updated every frame. Using the updated motion vector, the next position of the bat is predicted. If a similar-sized pixel cluster of the correct polarity is found at this predicted location, within a selectable error tolerance, then a track is established. This process is iterated frame-by-frame generating an output file of individual bat tracks. This process is described in detail and data are presented from an imaging survey of a bat emergence containing several thousand bats.

Date Published: 25 May 2005
PDF: 10 pages
Proc. SPIE 5811, Targets and Backgrounds XI: Characterization and Representation, (25 May 2005); doi: 10.1117/12.603785

Published in SPIE Proceedings Vol. 5811:
Targets and Backgrounds XI: Characterization and Representation
Wendell R. Watkins; Dieter Clement; William R. Reynolds, Editor(s)