[Insight-developers] Requiring DirectionCollapse for 3D to 3D extraction

[Bradley Lowekamp]

On Feb 10, 2011, at 9:08 AM, Johnson, Hans J wrote:

> Brad,
>  
> Tounge-in-check response:  Yes, of course the strategy is still needed....In that case the strategy is often obvious that the directions should stay the same :)  You always need a strategy.


Ok.

>  
> The old fitler would change behavior based on whether the image sizes were the same, and also based on the data that was presented to the filter.  This was cuasing several subtle algorithmic failures that were really hard to track down.  There was no way to do this in a backwards compatible manner, so I took a path that explicitly raised the issue with all developers and force them to make an informed decision about what they wanted to do.  We have previously tried to guess what the correct strategy is programatically, but that was a horrible failure and often caused application to fail based on what data was provided.  We had a situation where we could not find a universal solution to the problem without asking the application programmer to review the intent of the filter.

I think I understand the problem.

However, the documentation related to this issue is not clear for the 3D->3D case.  What is the preferred strategy when there is no collapsing?

Brad

>  
> Hans
>  
>  
> From: Bradley Lowekamp [blowekamp at mail.nih.gov]
> Sent: Thursday, February 10, 2011 8:00 AM
> To: ITK Developers
> Cc: Johnson, Hans J
> Subject: Requiring DirectionCollapse for 3D to 3D extraction
> 
> Hello Hans,
> 
> When doing a 3D to 3D subregion extraction with the itk::ExtractImageFilter is the DirectionCollapse strategy really required?
> 
> Brad
> 
> ========================================================
> Bradley Lowekamp  
> Lockheed Martin Contractor for
> Office of High Performance Computing and Communications
> National Library of Medicine 
> blowekamp at mail.nih.gov
> 
> 
> 
> 
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========================================================
Bradley Lowekamp  
Lockheed Martin Contractor for
Office of High Performance Computing and Communications
National Library of Medicine 
blowekamp at mail.nih.gov


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