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Copyright:
1996, 1999, 2006
J.A. Sethian

Evolving Curves: General Flow
A
closed curve moving under its curvature,
shrinks to a circle and disappears.
This Java Applet provides a tool to examine a more general
speed law.
This time, imagine a curve moving perpendicular to itself with
speed F. Curvature flow comes from letting F=K, where K is the curvature.
A more general speed law is given by
F=(1Alpha) + Alpha * K
The two extreme cases are
 Alpha=0.0: then the curve uniformly expands, and grows bigger and
bigger.
 Alpha=1.0: then the curve moves under curvature, and shrinks into a
circle and disappears.
Instructions:
To explore various flows, first input a value for
Alpha between 0 and 1. Be sure to then press Enter/Return on your
keyboard. Then, draw the curve in the box below.
Instructions:
Using your mouse, click several points on the white panel
to define the vertices of a polygon. When you are finished
entering the points, press the "Draw Curve" button.
At any time prior to pressing "Draw Curve" you can change the
alpha value by enter a new number and pressing return. Once
Draw Curve is clicked, the vertices will connect and the Level Set
Evolution process will start. Press "Stop" to end the program before
completion. To do it again, reload the page.
Some things to watch out for:
 If the evolving curve hits the side of the box, it will keep
on expanding.
 Starting with a perfect circle and the right choice for "Alpha"
the competition between expansion and shrinkage will be balanced, and
the curve will just sit there.
If You Want To Learn More:
An introductory resource about level set methods and applications:

