Figure 4.

Assign beads and bonds. (A) BOC from Fig. 1D. Individual chains are colored differently. Solid and dashed arrows (paths 1 and 2) denote counterclockwise and clockwise search directions along the bead boundary from the arbitrarily chosen seed bead (circled) to construct the outer chain. (B and C) Zoomed-in views of the rectangles in (A). One grid window represents one pixel. Beads and bonds are added as new edges meet the bond length cutoff b₀. Beads are assigned at pixel corners. (C) For boundary forming a closed contour, only one search direction is needed. The last bond added to close the contour is marked in cyan. Note that the sharp bend marked by a star is retained after smoothing (cf. Fig. S2).