Converting a surface source estimate object to nifti

I have been trying to convert a mne source estimate object into a nifti object. I do know that there is a way to convert a VolSource Estimate object from mne into a nifti object but there is no direct function that I have found from mne SourceEstimate to be outputted as anything other than a src or h5 source estimate file.
I need then to either find a way to convert it directly from surface source estimate to nifti or from surface to volume source estimate. Can anyone shed some light on how to do this?