[Insight-developers] ImageRegion bounds caching

[M Stauffer (V)]

Hi,

I think I wasn't clear. We're not trying to catch NaN exceptions or
explicitly identify NaN's. But rather we want ImageRegion::IsInside to
return false when a NaN is present in the input index.

We first saw a problem in ImageFunction::IsInsideBuffer, which was
returning true for indecies containing one or more NaN's. I submitted a
separate patch to fix it to return false when NaN's are in the input
index.
See http://review.source.kitware.com/#change,1110

Cheers,
Michael 

>-----Original Message-----
>From: Williams, Norman K [mailto:norman-k-williams at uiowa.edu] 
>Sent: Tuesday, March 01, 2011 4:47 PM
>To: M Stauffer (V); Luis Ibanez
>Cc: ITK
>Subject: Re: [Insight-developers] ImageRegion bounds caching
>
>2 things:
>
>1. Turning on numerical exceptions would have caught this.
>2. I don't know if there's a safe way to test for NaN and inf 
>values with
>numeric exceptions turned on. If you're testing for them, it 
>could make it
>so nothing would work with floating point exceptions turned on.
>
>On 3/1/11 2:27 PM, "M Stauffer (V)" <mstauff at verizon.net> wrote:
>>I will however add to ImageRegionTest to make sure that IsInside(
>>ContinuousIndex ) returns false for NaN and Inf values, as I did
>>recently for ImageFunction::IsInsideBuffer. Currently
>>ImageRegion::IsInside ContinousIndex ) does return false for NaN, but
>>only because NaN is cast to integer which yields a massive negative
>>number that is out of bounds. The test will make sure this 
>works on all
>>platforms and remains this way in the future.
>
>
>
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