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

[Jay Li]

Hi Dženan,

I appreciate your suggestions/answers. Thank you very much. It's really helpful.

Regards,
Jay

--- On Fri, 8/13/10, 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: Friday, August 13, 2010, 3:28 AM

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> 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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