[Insight-users] How ITK handles non-equal spacing images

[Dženan Zukić]

Hi Jay!

That approach is called 2.5D. It was common 10-15 years ago, but it is no
longer common because you basically ignore information using it. I also deal
with similarly anisotropic images (0.625 in x and y, 4.4 in z). And yes, low
Z resolution is a pain in the butt, but if you restrict yourself to sequence
of 2D slices, good results become harder to achieve.

But reading your arguments, I can see the point - I haven't given it much
thought until now. And I don't consider myself to be an expert either.

Regards,
Dženan

2010/8/13 Jay Li <chyumm at yahoo.com>

> Hi Dženan,
>
> Thanks for your input. I'm hoping to get a feeling on how to choose
> appropriate algorithms/filters for 3D non-equal spacing images in general. I
> was told that it would be more appropriate to perform 2D filters than 3D
> filters to the image I described in the first email (0.2 mm spacing along x,
> y, 1 mm spacing along z), because the spacing in z direction is five times
> of it along x and y. As I'm not an expert in image processing, I don't know
> if this is a common approach in the industry. I'm kind of hoping experts on
> this forum could give me some insights. Thank you again.
>
> Regards,
> Jay
>
> --- On *Tue, 8/10/10, Dženan Zukić <dzenanz at gmail.com>* wrote:
>
>
> From: Dženan Zukić <dzenanz at gmail.com>
> Subject: Re: [Insight-users] How ITK handles non-equal spacing images
> To: "Jay Li" <chyumm at yahoo.com>
> Cc: insight-users at itk.org
> Date: Tuesday, August 10, 2010, 9:12 AM
>
>
> Hi Jay,
>
> ITK image has support for different spacings along each axis, unfortunately
> not all filters take this information into account (most should though). The
> best way to check is to take a look at the source code.
>
> Regards,
> Dženan
>
> On Tue, Aug 10, 2010 at 02:54, Jay Li <chyumm at yahoo.com<http://mc/compose?to=chyumm@yahoo.com>
> > wrote:
>
> Dear ITK Users,
>
> I have a question regarding how ITK handles images with non-equal
> spacings in general. For example, I have a 3D volume with the spacing of 0.2
> mm along X and Y axis respectively, but 1 mm spacing in Z direction. If
> I apply a 3-D level set segmentation algorithm to the image, is this going
> to be a concern due to the larger spacing in Z direction? Or instead should
> I try 2-D  level set segmentation slice by slice on X-Y plane? Any
> suggestion is appreciated. Thank you.
>
> Regards,
> Jay
>
>
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