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Bug 2984 - Nonlinear normalisation distortions
| Status |
NEW |
| Reported |
2015-10-14 13:35:00 +0200 |
| Modified |
2015-10-14 13:35:21 +0200 |
| Product: |
FieldTrip |
| Component: |
external |
| Version: |
unspecified |
| Hardware: |
PC |
| Operating System: |
Windows |
| Importance: |
P5 normal |
| Assigned to: |
Robert Oostenveld |
| URL: |
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| Tags: |
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| Depends on: |
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| Blocks: |
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| See also: |
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Maité - 2015-10-14 13:35:21 +0200
Default parameters (flags) in Fieldtrip’s spm_normalise() are different from SPM’s spm_normalise(). In Fieldtrip, the amount of regularization is too low (= 0.1, line 144 in spm_normalise) compared with SPM’s default (=1).
This also affects the computation of MNI-aligned individual grids because there is an implicit normalization step.
Possible solutions:
- Call/substitute Fieldtrip’s spm_normalise() by SPM’s function or change Fieldtrip’s default flags values.
- Perform the normalization outside in SPM and provide the cfg.spmparams.flags. However, there is a bug in ft_volumenormalise() using that option.* Reported in another bug.