GroupwiseRegistration notebook: ERROR: the direction cosines matrix of the fixed image is invalid!

[thewtex]

Error:

itk::ExceptionObject (0x562ce335dd80)
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Location: "unknown" 
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File: /work/build/cp38-cp38-manylinux_2_28_x86_64/_deps/elx-src/Components/Metrics/VarianceOverLastDimension/elxVarianceOverLastDimensionMetric.hxx
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Line: 71
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Description: ITK ERROR: VarianceOverLastDimensionMetric(0x562cdaf45be0): 
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ERROR: the direction cosines matrix of the fixed image is invalid!
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  The VarianceOverLastDimensionMetric expects the last dimension to represent
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  time and therefore requires a direction cosines matrix of the form:
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       [ . . 0 ]
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  dc = [ . . 0 ]
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       [ 0 0 1 ]

@N-Dekker any ideas?

[N-Dekker]

@thewtex Thanks for asking! This check was added by commit SuperElastix/elastix@e9a02d9 (Aug 6, 2014). Can you possibly still print the direction matrix of the fixed image, to get more details? I mean: this->GetElastix()->GetFixedImage()->GetDirection() at https://github.com/SuperElastix/elastix/blob/ef03c8d1795ed78e889e273fc8d3b93c6da53683/Components/Metrics/VarianceOverLastDimension/elxVarianceOverLastDimensionMetric.hxx#L59

[thewtex]

@N-Dekker thanks for taking a look! 🙏

The direction is:

1 0 0
0 1 0
0 0 -1

(note the -1).

[N-Dekker]

@stefanklein @mstaring Do you possibly have a clue?

[mstaring]

the -1 should be a 1, as this is groupwise registration

[thewtex]

I am not sure why the associated notebook test started to fail:

https://github.com/InsightSoftwareConsortium/ITKElastix/actions/workflows/build-test-package.yml