Proceedings PaperUnderwater Tracking In Three Dimensions Using The Direct Linear Transformation And A Video-Based Motion Analysis System
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Although kinematic measurements can be made underwater using traditional electro-mechanical transducers, the additional complexity introduced by an underwater environment can be prohibitive. Further, many activities which occur underwater defy quantification by traditional methods. Optical techniques are another avenue which can be considered. Various optical systems have been devised for quantifying motion, but none has addressed the underwater problem in a general fashion--as a class of problems to be solved. Close-range tracking in three dimensions has been performed in air using the Direct Linear Transformation. 1,2 However, this algorithm is not valid when the image-forming rays are bent by refraction at an air/water interface. Although a (non-linear) adaption of the Direct Linear Transformation could be developed, for most purposes the additional complex-ity of such an algorithm would be prohibitive for automated tracking. This paper describes a simple, physical solution to the refraction problem which has been used for several applications involving automated underwater tracking in three dimensions using a video-based motion analysis system.