Lianrui Zuo
Atlas
1988

Snakes

Given scattered evidence of edges, how do we find one closed boundary?

Primary source M. Kass, A. Witkin and D. Terzopoulos, “Snakes: active contour models,” International Journal of Computer Vision, vol. 1, no. 4, pp. 321–331, 1988. doi:10.1007/BF00133570

A loop of 64 beads, started as a circle, settles on the object’s boundary. It prefers to be short and smooth, and the image pulls it toward edges. Switch to the energy landscape to see what the beads feel: valleys along edges, flat ground elsewhere.
The same loop with the image switched off. Short and smooth is all it wants, so it shrinks straight through the boundary to a point.

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