[Sea-mat] various

[Darren Weber]

Hi,

I have just come across this community and seek some help.  If you read on, you might find some useful tools among my stuff too, although they are probably covered by sea-mat already.

I am developing a matlab toolbox for human scalp electroencephalograpy (EEG) topographic mapping, among other things.  See http://eeg.sourceforge.net - there are some useful functions among it.

I would like to ask a couple of things of this community.

1.  I wonder if anyone has a matlab function for fitting a tesselation to an object?

For example, I would like to tesselate magnetic resonance images (MRI) of the human head.  Commercial programs often use a shrink-wrap technique.  This involves creating a tesselated sphere larger than the head and then moving the vertices toward the head until they reach a scalp intensity threshold in the MRI image volume.  They also incorporate some vertex "adhesion" or nearest neighbour distance and/or angle and/or intersection restrictions ("smoothness").

2.  I am also interested in development of spherical or realistic spline Laplacian routines in matlab.  My work involves interpolating the electric potential over the scalp, often with surface contours.  Matlab is frustrating because the contours can be so damn accurate they look sharp and nasty, rather than nice smooth curves.  I would be eternally grateful if you can offer any advice on this matter.

If any would like Laplacian functions for a mesh, my toolbox above has a Laplacian routine - called mesh_laplacian.m and also an interpolation function that minimises the Laplacian - the .m files contain a journal reference.  The results are quite nice, but I haven't yet tried to contour it and I'm afraid the matlab tools for this will not do a nice job.

There are also some simple functions for tesselating a sphere of any radius, fitting irregular vertices to a sphere or ellipse and visualizing scalar values on 3D surfaces (using patch).  If you would like more information, see the website above or ask me.

I write to this list with the view that ocean and weather system math, computing and visualization is very similar to electric current/potential for the human head.

Thankyou for your consideration.

Kind regards, Darren

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