Precision vs. Accuracy Dilemma in Point-Based Rigid-Body Registration

Abstract

The purpose of a registration procedure is to determine the transformation between two coordinate frames: the working frame (from which 3D data are transformed) and the destination frame (to which the data are transformed). In point-based, rigid-body registration, the transformation is calculated from measurements of the same physical points acquired in both frames. These two sets of corresponding points are called fiducials, and the quality of registration is frequently gauged by the root mean square (RMS) of distances between the fiducials measured in the destination frame and corresponding fiducials transformed from the working frame. However, in practical applications another metric is more useful: RMS of distances between targets measured in the destination frame and the corresponding targets transformed from the working frame. Targets are points to which registration transformation is applied, but they are not used to calculate the parameters of the transformation. Thus, smaller target’s RMS would correspond to a more accurate registration. Noisy measurements of fiducials in both frames yield noisy registration parameters, and they cause the uncertainty of the target