Closed figure expansion/contraction algorithm

[Ted Hill]

Hello,

I am working on a medical imaging application and I need to be able to
'expand' and 'contract' closed shapes. These are defined in two dimensions
as an ordered set of x,y points.

I am wondering if anyone knows of an algorithm in the public domain that can
be
used for this?

For example, in my application a physician may trace a line around a tumor
using the mouse
(thus defining the set of x,y points). Then the physician may want to expand
the
shape by adding a 1 cm margin around it. Alternatively, the physician may
want to 'shrink' the contour.

Thank you for any suggestions,

Ted Hill
Software Engineer
www.tomotherapy.com



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