Hello,

Someone sent me a while ago an E-mail asking how to go about averaging the geometry of multiple surfaces from different subjects. I was extremely busy and could not respond in time. Now the E-mail is buried somewhere I cannot find. The moral of this story is: Use the message board, it is a lot better.

First you'll need to have the same mesh for all the surfaces you will be using. If that is not the case (most likely), then perhaps you can use MapIcosahedron to create standard-mesh versions of these surfaces.

To average the coordinates, you can use 1deval. This program is the equivalent of 3dcalc for 1D data. To get the coordinate list for a surface, I suggest you use the program ConvertSurface to turn your surface into the 1D format (called vec format in that program). 1D file format consists of nothing but an ASCII file of node coordinates and another file containing the triangulation.

After averaging node coordinates and writing the output into a new 1D coordinate file, create a spec file for the average surface using the program quickspec . To define the average surface, you’ll be using the average coordinate file and the same triangulation as any of the other surfaces.

I will be away until next Thursday.

Cheers,
-ziad