Automatic landmark annotation accuracy in “double-pass” mode. (a) Box-and-whisker plots of the point localisation errors for automatic annotation of 50 skull landmarks on the 12 consomic Mus musculus specimens (read against the left-hand scale), using the second set of manual landmarks. The algorithm was applied in “double-pass” mode with no initial, point-based stage of registration. The black squares and red crosses show, respectively, the percentage of points passing the outlier test and the percentage within the error threshold (read against the right-hand scale); only points passing the outlier test have been included in the box-and-whisker plots. (b) ROC curve of the true and false positive rates of points passing the outlier test; the dashed line shows the operating point.