dwipreproc explicit volume recombination #1493
Description
Line 996 in 16090b5
translates to
mrcalc field_map.nii.gz 0.123 -mult - | mrfilter - gradient - | mrconvert - field_deriv_pe_1.mif -coord 3 1 -axes 0,1,2
causing
mrcalc: [100%] uncompressing image "field_map.nii.gz"
mrcalc: [100%] computing: (field_map.nii.gz * 0.123)
mrfilter: [100%] applying smoothing prior to calculating gradient
mrfilter: [100%] applying gradient filter to image -
mrconvert: [ERROR] omitted axis "4" has dimension greater than 1
when performing explicit volume recombination
field_map.nii.gz is 4D containing 6 volumes
after mrfilter this becomes 5D containing 3 x 6 volumes
subsequent mrconvert then fails when trying to omit a non-singleton dimension