In an attempt to find whether there are predictable peaks along the collagen like domain of SP-D arms two different types of AFM images (Arroyo et al mentioned amplitude modulation mode) I measured (in the supplemental figures 2 and 4). Plots using FIJI (Image2, ImageJ, all three versions seem to perform similarly) in these two comparisons show three distinct and one not so distinct peaks in the collagen like domain.  Pink dotted rectangles show peak valleys that seem to correspond between the height image with hand drawn line (top part of the figure), and the flat image with LUT plots drawn from a node-cusp line drawn on the grayscale (converted from image in middle) (middle and bottom part of my composite figure). N termini (left brightest portion of the dodecamer, CRD on the right.