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Three markers chosen on the topography reference image (a) and the compared topography image (b). The SIFT algorithm was used to determine the drift between the images, and the images were overlaid in part (c). All of the markers from parts (a, b) were projected on the overlaid image (c), and the difference can be observed. We found a maximum difference of ± 12.9 nm in x and ± 9.3 nm in y.
