[Insight-users] Help with Shaped Neighborhood Iterators: Setting and Retrieving Offsets - mismatches

[Neal R. Harvey]

To show the problem more simply:

Here's a short snippet of code where I set offsets for a shaped 
neighborhood and then immediately retrieve this offset. I then print the 
value of the offset I thought
I was setting and the value that I retrieved:

        MissOffset[0] = static_cast<int>(x);
        MissOffset[1] = static_cast<int>(y);
        MissNeighborhoodIterator.ActivateOffset(MissOffset);
        MissNeighborhoodIterator.SetPixelWeight(z, 
static_cast<InputPixelType>((MissSEPixelValue)));

        std::cout << "   x = " << x << ": y = " << y << std::endl;
        std::cout << "   MissOffset[0] = " << MissOffset[0] << ": 
MissOffset[1] = " << MissOffset[1] << ": MissSEPixelValue = " << 
static_cast<int>(MissSEPixelValue) << std::endl;

        std::cout << "   Retrieved:MissOffset[0] = " << 
MissNeighborhoodIterator.GetOffset(z)[0] << ": Retrieved:MissOffset[1] = 
" << MissNeighborhoodIterator.GetOffset(z)[1] << ": 
Retrieved:MissSEPixelValue = " << 
MissNeighborhoodIterator.GetPixelWeight(z) << std::endl;

I often get outputs such as the following:

   x = 3: y = -2
   MissOffset[0] = 3: MissOffset[1] = -2: MissSEPixelValue = 14
   Retrieved:MissOffset[0] = -2: Retrieved:MissOffset[1] = -2: 
Retrieved:MissSEPixelValue = 14

    Here, we can see that the retrieved value of the offsets do not 
match those just set! However, the set values for the PixelWeights are
    always in agreement with those retrieved.