FIGURE 5.

An illustration of the Mahalanobis distance calculation. A, A critical structure (black), safety margin (cyan), and analyzed shell (gray) are shown. The risk to the critical structure of milling a specific point (yellow star) is examined. The shortest distance between it and the critical structure is shown in red. B, ‘Whitened’ space, formed by applying the whitening transformation. The shortest distance is shown in yellow. C, In the whitened space, the probability that the point is within the yellow ellipse is easily obtained. The complement of this probability is a conservative estimate of the probability that the registration error could cause the center of a mill bit at the center of the circle to fall within the critical structure