Extended Target Tracking Using ET-PMHT for 3D Convex Polytope Shapes With Partial Visibility

This article discusses the problem of tracking a single 3D extended target (or widely separated targets) with convex polytope shape when the target may only be partially visible. An extended target (as opposed to a point target) may generate multiple measurements in a single frame. With the advent of high-resolution sensors (such as LiDAR), the targets need to be considered as extended targets and their shape as well as kinematics need to be estimated. The extended target may only be partially visible (self-occlusion) and the measurements occur only from the visible parts of the target. In this work, different parts of a single extended target are assumed to be different targets constrained by the rigid body motion of the whole target, and the multitarget tracking framework is used to handle the tracking. The target shape is described using a convex hull represented by its vertices and a Delaunay triangulation. The point target PMHT is modified to develop an extended target PMHT (ET-PMHT) joint association and filtering by assuming that the face triangulations are separate targets. Face management is incorporated into the algorithm to delete erroneous faces and the algorithm is able to add new faces to refine the shape estimate. The framework can handle self-occlusion (partial visibility) by associating measurements only to the visible parts of the target. The algorithm's performance is compared with the 3D Gaussian Process under various scenarios, and RMSE of the centre, velocity and IoU metrics are used to quantify the performance. The proposed algorithm is able to outperform the 3D Gaussian Process in the centre RMSE metric by about 40% while achieving an IoU of 0.6 (on average) even when the target is only partially visible.