Alon,
The surface normals are not stored in a file. For each coordinate
file that is loaded into Caret, the normals are computed using the
coordinates and the topology file associated with the coordinate file.
Normals are computed as follows:
* Compute the normal vector for each triangle in the surface
* For each node, assign it a normal vector that is the average of the
normal vectors of the triangles that use the node
* Convert each node's normal to a unit vector (length equals 1.0)
If you want to see the values of the normal vectors, use File Menu-
>Export File and write a surface as either a VTK surface file or a
VRML file. Both of these files include coordinates, surface normals,
and topology. Simply search one of these files for the characters
"Normal".
----------------------------------------------------------
John Harwell
[EMAIL PROTECTED]
314-362-3467
Department of Anatomy and Neurobiology
Washington University School of Medicine
660 S. Euclid Ave. Box 8108
St. Louis, MO 63110 USA
On Jun 6, 2007, at 5:31 AM, Alon Keren wrote:
Hello,
I would like to extract from CARET a list of normals to the
cortical surface at each node. I saw that CARET can show these
normals (Display Control window --> Page Selection list --> Surface
Miscellaneous --> Show Normals checkbox). Are these data stored in
a specific file, or are the normals computed from the topography
file? Where are they stored or how are they computed?
Thanks,
Alon.
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