[Insight-developers] itk::ImageBase::TransformIndexToPhysicalPoint/TransformPointToContinuousIndex ignores spacing?

[Bill Lorensen]

1) If we add this class, shouldn't we also add a class that works with
scalar images: LinearInterpolateNearestNeighborExtrapolateImageFunction.
and,
2) If we add this class, shouldn't this class use
VectorLinearInterpolateImageFunction internally for points that are
inside the region? I hate to see duplicated code.

Or,
3) Do we need this new interpolator at all? Why not do the inside
region test in the class that uses
VectorLinearInterplateImageFunction?

Bill

On Tue, Mar 17, 2009 at 12:29 PM, Tom Vercauteren
<tom.vercauteren at m4x.org> wrote:
> Well, what is the policy for moving a class from review to ITK proper?
>
> It might be a good time to move this interpolator if someone needs it
> for a bug fix.
>
> Thoughts anyone?
>
> Tom
>
> On Tue, Mar 17, 2009 at 20:12, kent williams
> <norman-k-williams at uiowa.edu> wrote:
>> This is actually exactly what I need, but unfortunately, I can't change a
>> filter that is part of ITK proper to depend on a class in review ;-)
>>
>>
>> On 3/17/09 1:57 PM, "Tom Vercauteren" <tom.vercauteren at m4x.org> wrote:
>>
>>> Kent,
>>>
>>> You might also want to switch the interpolator for an
>>> interpolator/extrapolator such as the one I contributed to the Review
>>> directory:
>>> http://www.itk.org/Doxygen/html/classitk_1_1VectorLinearInterpolateNearestNeig
>>> hborExtrapolateImageFunction.html
>>>
>>> With this function, all points are considered as inside the buffer. I
>>> think that this approach makes sense in your case.
>>>
>>> Hope this helps,
>>> Tom
>>>
>>> On Tue, Mar 17, 2009 at 19:43, Bill Lorensen <bill.lorensen at gmail.com> wrote:
>>>> Look at what I did in ShrinkImageFilter recently. At Hans's request
>>>> (do we all work for Hans?) I changed the subsampling so that the image
>>>> centers aligned.
>>>>
>>>> Bill
>>>>
>>>> On Tue, Mar 17, 2009 at 11:33 AM, kent williams
>>>> <norman-k-williams at uiowa.edu> wrote:
>>>>> I was aware of the issue, just never tripped over it before.
>>>>>
>>>>> I'm just not sure how to deal with it in this case.  It points out a
>>>>> fundamental problem in what I'm trying to do.  The net effect is this:
>>>>>
>>>>> Image A has dimensions { n, n, n } and spacing { s, s, s }
>>>>> Image B has dimensions { n/2, n/2, n/2 } and spacing { s*2, s*2, s*2 }
>>>>> Assume origin = { 0, 0, 0 } for both, and both are in the same orientation.
>>>>>
>>>>> Any physical point on an edge farthest from the origin -- e.g. { n-1, y, z
>>>>> }, { x, n-1, z }, { x, y, n-1 } etc -- is INSIDE image A, but NOT INSIDE
>>>>> image B.  Even though the two images theoretically have the same volume.
>>>>>
>>>>> And this is independent of whether the index is center-of-voxel or corner of
>>>>> voxel, or whether you're a North-going Zax or a South-going Zax.
>>>>>
>>>>> The mind reels.
>>>>>
>>>>> On 3/17/09 1:01 PM, "Tom Vercauteren" <tom.vercauteren at gmail.com> wrote:
>>>>>
>>>>>> Hi Kent,
>>>>>>
>>>>>> You might already be aware of that bug:
>>>>>> http://www.itk.org/Bug/view.php?id=6558
>>>>>>
>>>>>> Right now the use of rounding vs. truncation is not consistent within
>>>>>> the index <-> world transformations.
>>>>>>
>>>>>> Tom
>>>>>>
>>>>>
>>>>>
>>>>>
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