[Insight-developers] Problem with LabelMap and negativ spacing

[Carsten Kendziorra]

Hi Brad,

my binary image is extracted from a DICOM with negative spacing in 
z-direction. I didn't produce them and I'm not sure why some have 
negative and some positive spacing in z-direction, but in principle it's 
possible.

Carsten

On 06/07/2013 12:55 PM, Bradley Lowekamp wrote:
> Hi,
>
> I have always assumed that the spacing is positive. I am surprised that it wasn't enforced or check else where.
>
> Generally the direction cosine matrix is used for orientation.
>
> Why are you using a negative spacing? (that does just sound wrong to me)
>
> Brad
>
>
>
> On Jun 7, 2013, at 6:50 AM, Carsten Kendziorra <carsten.kendziorra at charite.de> wrote:
>
>> Hello,
>>
>> I'm using a itk::BinaryImageToShapeLabelMapFilter to create a itk::LabelMap and take afterwards a an object:
>>
>> itk::LabelMap::LabelObjectType* labelObject = labelMap->GetNthLabelObject(LabelNumber);
>>
>> Unfortunately
>> labelObject->GetEquivalentEllipsoidDiameter()
>> returns [-nan, -nan, -nan], if the spacing of the BinaryImage is negative. Everything works fine for positive spacing.
>>
>> Is negative spacing not allowed here? Or how to deal with negative spacing?
>>
>> Thanks for any help!
>> Carsten
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