Iterative Most Likely Point Registration (IMLP) A Robust Algorithm for Computing Optimal Shape Alignment
We present a probabilistic registration algorithm that robustly solves the problem of rigid body alignment between two shapes with high accuracy, by aptly modeling measurement noise in each shape, whether isotropic or anisotropic. For point cloud shapes, the probabilistic framework additionally enables modeling locally linear surface regions in the vicinity of each point to further improve registration accuracy. The proposed Iterative Most Likely Point (IMLP) algorithm is formed as a variant of the popular Iterative Closest Point (ICP) algorithm, which iterates between point correspondence and point registration steps. IMLP's probabilistic framework is used to incorporate a generalized noise model into both the correspondence and the registration phases of the algorithm, hence its name as a most likely point method rather than a closest point method. To efficiently compute the most likely correspondences, we devise a novel search strategy based on a principal direction (PD) tree search. We also propose a new approach to solve the generalized total least squares (GTLS) sub problem of the registration phase, wherein the point correspondences are registered under a generalized noise model. Our GTLS approach has improved accuracy, efficiency, and stability compared to prior methods presented for this problem and offers a straightforward implementation using standard least squares. We evaluate the performance of IMLP relative to a large number of prior algorithms including ICP, a robust variant on ICP, Generalized ICP (GICP) and Coherent Point Drift (CPD) as well as drawing close comparison with the prior anisotropic registration methods of GTLS ICP and A ICP. The performance of IMLP is shown to be superior with respect to these algorithms over a wide range of noise conditions, outliers, and misalignments using both mesh and point cloud representations of various shapes.
PloS one