Hi Anastasia!

 

That makes sense, thank you!  So the question is how do I evaluate the noisiness of a path?

 

1) Most of my isosurfaces look a lot noisier than your example on the wiki. There's obviously no hard and fast rule here but is there any way to gauge the noisiness of a reconstructed path? And can that information be used for quality control?

 

2) Another source of information on outliers is the log files that are produced when running -trac-all -stat (based on the shape of the tract). It doesn't seem to flag tracts that are (almost) completely missing (which are spotted by visual inspection in Freeview) - but they may fall under the minimum threshold and therefore not be evaluated?  Would you recommend automatically excluding the subjects that are flagged as outliers here?

 

>Hi Lars - A path with fewer control points will generally be smoother. So

>if the tract is pretty much a straight line, you might get a noisier 
>result if you increase the number of control points. But if the tract is 
>more convoluted than a straight line, then you need more control points to 
>define it accurately. So it's hard to predict the result of increasing the 
>control points in general, it depends on the specific case.

>BTW, if you change the number of control points, you don't need to use the 
>reinit variable - that's only for rerunning with the same control points 
>as before.
>
>Best,
>a.y

sincerely yours,

Lars M. Rimol, PhD
Senior researcher,
Norwegian Advisory Unit for functional MRI
Department of Radiology,
St. Olav's University hospital,
7006 Trondheim,
Norway