I have surface with ~73,400 vertices generated from the Freesurfer version 6 fsaverage brain, left hemisphere. I have a surface map that was created by mapping a volume to the fsaverage white surface. Is there a way to map the surface map to the new surface with less vertices? Is there a way to map values from the 73,000 vertices-map to the standard fsaverage pal surface?

Thanks in advance,