[Insight-users] weird behavior of ActiveShapeModelGradientSearchMethod related with number of iterations

[Sergio Vera]

Hello!

I've wrapped the example of Active Shape Models (ASM) found in the example
"itkActiveShapeModelCalculatorTest.cxx" with a small gui to be able to play
with the tolerance, iteration and profilelenght values.
Using the supplied model.mha and feet.mha images, the program runs smoothly
and generates a reasonably correct mean shape:

However, with the 2 iterations shown in the example cxx file, in the
ActiveShapeModelGradientSearchMethod  the process does not segment correctly
the image.  When incrementing the iteration steps, the result seems strange
to me.
The resulting polygon (that starts reasonably close to the target bone),
does not seems to deformate or adapt to the input image at all, and only
seems to move out of the image as iterations increase.

At 20 iterations the polygon is starting to be outside the image, with a
couple of vertex with negative x values, and at 21 iterations the
coordinates of the resulting polygon have skyrocketed to the order of
hundreds of millions of pixels.
At 22 iterations the application crashes.

Does any of you has experienced a similar behavior with this example?
Any clue for what may be happening?

Regards

Sergio
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