This procedure was designed to guarantee that the points obtained from regressions match the
points obtained from calliper measurements. At the end of this stage, we have the measurements of
distance between each pair of sides in all the replicates. The last step was to compare both sets of
measurements and to estimate the uncertainty of the scanner data. One hundred sixty distances were
measured in total (4 distances between opposite lines × 20 replicates × 2 modes).