Hi Victor

the sphere files are lh.sphere and rh.sphere in the surf dir. You could write out the metric tensor (or first fundamental form) of the mapping to compute Euclidean distances from spherical coordinates, or probably just use the 3D euclidean distances on the sphere as the sampling is dense enough that it won't make much difference unless you have pretty large kernels.

cheers Bruce

On Wed, 29 Nov 2017, Victor Montal Blancafort wrote:

Thanks Bruce and Doug!

Bruce, I think the option of the sphere is the one that better fits my needs, since I need to perform conv operations + derivatives. How should address this issue? I am not very familiar with sphere files (nor metric tensors) and do not know how to open/where to find those files.

Thank you once again! Bests,

Victor M