[Insight-developers] bug in itkGradientVectorFlowImageFilter

[Bill Lorensen]

Kishore,

Can you file a bug report and put your changes in the report?

Thanks,

Bill

On Mon, Oct 5, 2009 at 12:50 PM, Kishore Mosaliganti
<kishoreraom at gmail.com> wrote:
> Hi,
>
> itkGradientVectorFlowImageFilter does not make use of image spacing.
> It assumes isotropic spacing of 1 in all dimensions. This is a
> problem. In particular, the ITK implementation uses the definition of
> 'r' in Equation 17 which will change for anisotropic cases.
>
> Also, the CFL condition for estimating the time-step was incorrectly
> being computed. The original paper, "Snakes, Shapes, and Gradient
> Vector Flow" shows the equation incorrectly in Equation 18. It is well
> known that for the diffusion equation, it is (delta_x)^2 and not
> delta_x in the denominator.
>
> I corrected the code locally in my machine. Basically, I had to set
> the spacing in new images that were allocated and for the
> LaplacianImageFilter.
>
> I am attaching the modified code.
>
>
> Kishore
>
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