Abstract

An image tracking algorithm, which was originally used with the particle image velocimetry (PIV) to determine velocities of buoyant solid particles in water, is modified and applied in the presented work to detect motion of fire ant on a planar surface. A group of fire ant workers are put to the bottom of a tub and excited with vibration of selected frequency and intensity. The moving fire ants are captured with an image system that successively acquires image frames of high digital resolution. The background noise in the imaging recordings is extracted by averaging hundreds of frames and removed from each frame. The individual fire ant images are identified with a recursive digital filter, and then they are tracked between frames according to the size, brightness, shape, and orientation angle of the ant image. The speed of an individual ant is determined with the displacement of its images and the time interval between frames. The trail of the individual fire ant is determined with the image tracking results, and a statistical analysis is conducted for all the fire ants in the group. The purpose of the experiment is to investigate the response of fire ants to the substrate vibration. Test results indicate that the fire ants move faster after being excited, but the number of active ones are not increased even after a strong excitation.

Highlights

  • A vibration-based technique is under development at the University of Mississippi’s NationalCenter for Physical Acoustics (NCPA) for inducing motion of black imported fire ants (BIFAs) in a tub

  • The digital images of fire ants are recorded with a high resolution video system, processed to remove the background disturbances, identified with a recursive digital filter, and tracked with their position, size, brightness, shape and orientation angles

  • The fire ant image tracking is conducted in two ways, i.e. individual image tracking and ensemble image tracking

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Summary

Introduction

A vibration-based technique is under development at the University of Mississippi’s National. Image pairs are usually taken with a digital camera to record displacements of tracer particles in the plane during a selected time interval. Many different algorithms can be used to determine the particle image displacements in a digitized PIV recording pair so that the velocities of the flow tracers can be calculated. The authors constructed an image tracking technique for fire ants based on the method and algorithm used to determine the velocity of the buoyant solid particle in a water tank, i.e. the images of solid particles in the water tank were identified with a recursive digital filter, and they were tracked between frames according to the size, brightness, shape of the particle image [12, 13].

Experiment setup
Removing background disturbances
Image identification
Image tracking algorithm
Experiment results
Summary and conclusions
Full Text
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