We implemented this as part of the JCS Conflation Suite (which was the
reason JUMP was originally developed!)
There's a whole body of theory around shape recognition - much of which
is very complicated and hard to implement/use. The circularity ratio is
one of the more usable techniques.
Martin
On 4/27/2011 2:00 PM, Larry Becker wrote:
I had a need to classify polygon shapes into general categories such
as roads and buildings, and I though it might be possible to use a
"thinness" factor calculated using the area and perimeter. After
fooling around with it for a while and not getting the answer, I
goggled and found the following solution:
lCircularity ratio: the ratio of the area of the shape to the area of
a circle (the most compact shape) having the same perimeter.
(area-perimeter ratio)
M = ( 4 * Pi * Area of Polygon) / (Perimeter of Polygon)^2
For a circle, the ratio is one; for a square, it is ? / 4; for an
infinitely long and narrow shape, it is zero.
I found it at: http://ce.sharif.edu/~alamgir/
<http://ce.sharif.edu/%7Ealamgir/>
Further searches indicate that this method of classification may be
relatively unknown. Does anyone have knowledge in this area?
regards,
Larry Becker
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