finding the right output for synthetic fieldmap

I’ve recently been exploring the omni pipeline—thank you so much for making it publicly available, it’s been incredibly helpful!

I’m planning to use fmriprep for further preprocessing and would like to leverage the synthetic fieldmap generated by omni as a regular fieldmap for distortion correction.

I came across a file named iteration2_synthetic_epispace.nii and was wondering if this is indeed the correct synthetic fieldmap to use for this purpose. I’m asking because the file doesn’t quite resemble a typical fieldmap—it contains a lot of anatomical detail, which made me unsure whether it’s the right input for fMRIPrep’s distortion correction workflow. Could you kindly confirm whether this is the appropriate file to place in the fmap directory for compatibility with fmriprep, and whether this approach makes sense to you?