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

[kent williams]

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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