I am wondering the tracking error with iFOD2.
I made one fiber bundle and simulated the DWI ( 60 gradient directions and b=1000).
The DWI was added Rician noise with High SNR.
The fODF was estimated and I qualified it and confirm it was correctly estimated.
SD_Streem algorithm could track the fiber properly, but iFOD2 could not generate proper fibers.
Glad you got to the bottom of it. Indeed, the cutoff is going to be critical here. The default is set assuming your fODF has been estimated using (MSMT-)CSD with an appropriately calibrated response function, and/or intensity normalised using mtnormalise. This being simulated data, there’s a good chance the scaling differs from what’s expected, which would require a different cutoff.
Otherwise, if you used regular CSD (not the MSMT variant), the default cutoff is probably now too low for noisy data, especially if unconstrained using ACT – similar issue to this thread.
Or if you’re really interested in the interaction between CSD algorithm / tracking cutoff and tracking outcomes, check out this monster figure I made when we were in the process of revising the default cutoff.