[Insight-users] Region.PadByRadius results in infinite loop during iteration

[Charlotte Curtis]

I'm trying to iterate over a subregion of an image, but the iterator never
seems to know when it reaches the end of the region.  My image is fairly
large, but only a small portion of it is non-zero (it's a segmentation), so
I don't want to waste time iterating through the whole image.  The code that
doesn't work is as follows:

typedef itk::ImageMaskSpatialObject< Dimension >   MaskType;
MaskType::Pointer  mask = MaskType::New();
mask->SetImage( image1 );
ImageType::RegionType boundingBoxRegion =
mask->GetAxisAlignedBoundingBoxRegion();


boundingBoxRegion.PadByRadius(10);

ConstIteratorType itr1(image1, boundingBoxRegion);

for (itr1.GoToBegin(); !itr1.IsAtEnd(); ++itr1)
    {
         vol1 += itr1.Get() ? 1 : 0;
    }

The reason I am doing this is to compare two manual segmentations of the
same object.  It works just fine if I iterate over the entire image, but it
takes a while.  It also works if I don't try to pad the region, but then I
won't get accurate results because the discrepancies of one segmentation may
be slightly outside of the AxisAlignedBoundingBoxRegion of the other.  10
voxels seems like a fair margin of error, I doubt I could be off by that
much in my manual segmentation, so it seemed a reasonable approach.
However, the iteration loop keeps on going until it seg faults.  Is there
something else I should be doing to slightly increase the size of my
bounding box?
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