I am using the ?h.sphere.reg files automatically generated by reconall. However, I found that the area distortion compromise the results of my following resample step. I wonder whether replacing the default average surface "$FREESURFER_HOME/average/?h.average.curvature.filled.buckner40.tif" with the ?h.sphere in the /average/surf directory would reduce the distortion. If so, could anyone tell me how to get a .tif file using files in /average/surf directory?