[Insight-users] Problem with output of rigid registration of different sized 3d volumes

[sk012s0481_2 at blueyonder.co.uk]

We're working on 3d rigid registration using the example ITK code. We want
to register two datasets of different dimensions and obtain an output 3D
volume that encompasses both datasets. Our code is importing 2D DICOM
slices, and then exporting them as either one 3D dataset or another 2D
DICOM dataset.

We're currently finding the following problems:


1) If we export our registered result as one dataset, the dimensions of
the final result match the dimensions of our fixed image which we're
registering to. If the moving volume is smaller than the fixed volume then
this leads to loss of information, which we don't want.

e.g. When registering a 200x100x100 dataset to a 150x100x100 dataset, the
final result is 150x100x100, where we lose information from the other
dataset.

If we perform the registration the other way round, ITK produces a
200x100x100 dataset which fills in the non-existing slices in the moving
image with zero values. This is the behaviour we want when the dimensions
of the smaller dataset are smaller.



2) When doing a registration of a 150x100x50 dataset onto a 150x100x100
dataset, if we try and export as another DICOM series, the code crashes,
saying the following:

===========
Exception thrown while writing the series
itk::ExceptionObject (0126F0A8)
Location: "Unknown"
File: ...\insighttoolkit-2.4.0\code\io\itkImageSeriesWriter.txx
Line 312
Description: itk::ERROR: ImageSeriesWriter(018D1FE8): The number of
filenames passed is 50 but

100 were expected.
=========

It doesn't generate a result with the non-existant slices being filled in,
as is the case with the single file output code. Are there any ways we can
write out a DICOM series which does fill in the missing slices, and which
ultimately samples the overall volume of the entire registration result?

Thanks in advance for your time,

Rehan Ali