Development of a Field-Portable Omnidirectional Video System to Quantify Three-Dimensional Motion

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To study motion in natural settings, especially out of doors, a battery-powered weather proof two-camera video system and computer analysis system are developed. In the data collection system each camera is oriented and focused by a human operator. The cameras will be able to pan and zoom so that a subject can be easily followed. Other systems designed to study biological motion require that the orientation of the cameras be fixed, but here the pan and tilt angles measured by two optical shaft encoders (resolution 0.036 degrees) and zoom factor (measured by a linear shaft encoder) are stored at video frame rates (30 Hz) on the image in bar code. The two video images are synchronized in time by genlocking the cameras and mixing the same SMPTE time code with each video signal. The image processing system is consists of a RISC workstation that runs software to decode the pan and tilt angles of the cameras and the time code. In addition, the software can compute the pixel coordinates of the center of mass of multiple objects in each video frame. The object recognition software was designed by Dr. Jack Sanders-Reed of SVS Inc. and was originally used at weapons test ranges. It features modules for pixel processing, background clutter suppression, object detect and description, and frame to frame tracking. The camera angles and pixel coordinates of the center of mass of the objects from both cameras are used to compute the position of the objects in three-dimensional space as a function of time. From this basic information other important performance characteristics such as velocity, acceleration and turning radius and the distance between different objects can be computed. The new image analysis techniques will help automate the processing of video images, which if done manually is a time intensive activity. A series of collaborative experiments with 15 other scientists is designed to test the usefulness and versatility of the system for the study of a nimal locomotion, animal behavior and conservation biology under field conditions. This instrumentation greatly increases our ability to quantify motion and behavior outdoors. It will provide flexibility in data gathering and power for image analysis that no commercial motion analysis system can match.