| Re: Image segmentation programs in IDL? [message #51880 is a reply to message #51879] |
Thu, 14 December 2006 06:54   |
Paolo Grigis
Messages: 171
Registered: December 2003
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Senior Member |
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Tim wrote:
> Thanks to everyone for their interest.
>
> 3) So my purpose now is to get a list of grid points in each black
> region. Then I will calculate, for example, the moment of inertia of
> each object about its center of mass (to use the physics terms) then
> subtract the moment of inertia of a circle of the same area, then
> divide by the moment of inertia of the circle of the same area.
> Finally, I will average this quantity over all the objects in the
> image. That should give me a number which quantifies the
> "non-circularity" of the objects in the image.
Be careful that you want your quantity of "non-circularity",
however you are defining it, not to depend on rotations of
the system (that is, on the axis with respect to which you
compute the momenta). There is a way of expressing the inertial
momenta in a frame-independent form, but this will give you
two numbers...
Ciao,
Paolo
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