Exporting just the supra-threshold streamline vertices is unfortunately not something immediately accessible. Hopefully in the future the
tckedit -mask option will be able to take a fixel mask as input, which would probably serve this purpose (albeit without TSF-based smoothing).
You could generate a voxel mask of those voxels containing at least one supra-threshold fixel and then mask streamline vertices based on that, but it wouldn’t get you all the way to the data you want.
The other alternative is to make use of the MatLab functions for reading both
.tsf files, select only streamline vertices for which the value in the TSF is supra-threshold, and then write the result to a new
.tck file. You do however need to be wary when masking streamlines in this way that you can have an individual input streamline lead to multiple output streamlines due to being bisected by the masking process.