Hi Jackson,
PROBTRACKX does probabilistic interpolation.
This means that the voxel from which you are drawing your next orientation will be probabilistically defined based on the current position of the streamline. I.e., if you are standing very close to the edge of v, you will likely be sampling the PDF from the neighbour of v rather than from v itself.
Hope this helps, cheers,
Matteo
> On 20 Apr 2016, at 18:29, Jackson Smith <[log in to unmask]> wrote:
>
> Hello,
>
> I would like to know how probtrackx2 uses its fibre orientation PDFs while generating streamlines. Unfortunately, I'm having trouble fully understanding Behrens et al (2003), and I haven't found answers on the forum. Let's say that a streamline is currently at a point near the edge of voxel v. Will the direction of the next step be sampled from the PDF of v alone? Or, will some interpolation of neighbouring PDFs be used?
>
> Best,
> Jackson
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