Hi,
You are right that all that matters is consistency.
If you are getting your bvecs generated for you by some reconstruction tool (like dcm2nii) or from a pre-processed dataset then you need not worry about any of this. It is only really important if you are making your own bvecs (or using them outside of FSL) or if you are manipulating the image in some way (e.g. rotating it). For the latter we provide a utility called fdt_rotate_bvecs. If it is the former then you need to understand the details in the FAQ, as the voxel coordinates explained there are not the standard NIFTI voxel coordinates, and therefore have fixed handedness (the “radiological orientation”). It is mainly because of this internal convention (that you normally don’t have to worry about) that these things get a little confusing.
All the best,
Mark
> On 27 May 2019, at 17:50, Steven Tilley <[log in to unmask]> wrote:
>
> Hello,
>
> I wanted to clarify my understanding of the bvecs file. This message [1] says that bvecs is in voxel coordinates. However, the FAQ [2] says that it assumes radological orientation. If it is truly in voxel coordinates, that it really shouldn't matter how the data is stored, so long as the two files are consistent, correct?
>
> 1. https://www.jiscmail.ac.uk/cgi-bin/webadmin?A2=FSL;f4c2eecb.06
> 2. https://fsl.fmrib.ox.ac.uk/fsl/fslwiki/FDT/FAQ#What_conventions_do_the_bvecs_use.3F
>
> Thanks
> Steve
>
> ########################################################################
>
> To unsubscribe from the FSL list, click the following link:
> https://www.jiscmail.ac.uk/cgi-bin/webadmin?SUBED1=FSL&A=1
########################################################################
To unsubscribe from the FSL list, click the following link:
https://www.jiscmail.ac.uk/cgi-bin/webadmin?SUBED1=FSL&A=1
|