BrainVISA

Hello,

I'd like to use the Tailarach transformation calculated by BrainVisa and I want to understand better what this trasformation maps.
Does it maps the i,j,k voxel indexs to Tailarach Space or the AIMS x,y,z coordinates to Tailarach space? I guess it should be the second.
In this case, I know that, having a Nifti-1 image, the AIMS-To-NiftiWorld matrix is stored in the minf file ('scanner-based anatomical referential'), thus, if
I want to go to the voxel indexes i,j,k to Tailarach Space I need to apply the following transformation matrix: niftiMatrix * inverse(AIMS-To-NiftiWorld) * tailarchTransformMatrix.
Does this sound correct?

Hi,
Yes, it is Aims x,y,z to Talairach.
The voxels (in disk space) to Aims matrix is also in the header info (either the .minf file, the header object if scripting with pyaims, or the result of AimsFileInfo command) in the "storage_to_memory" field, which you maybe should use instead of scanner-based (which could represent a transformation to a different, rotated, space).
I don't entirely understand which transform you need: which are exactly your source and destination coordinates systems ?
If you need to go from disk-oriented voxels to Talairach, it would be:
tailarchTransformMatrix * voxel_size * storage_to_memory (if I am right)
Notice also that our Talairach space is also Aims oriented, contrarily to the MNI convention.
Please look at: the coordinates systems description.

Denis