Hi,

We need to display surface data (.w file). However, our algorithm failed
to assign values for some vertices (and were therefore given the value of
exactly zero), and to clearly differentiate those from vertices where we
successfully computed values, we would like the vertices where we could
not compute a value to be blank (=only the underlying anatomical surface
shows).

Normally I would just threshold the values to get rid of the "blank"
vertices. However, we want to use tksurfer "offset 0.5" to shift the
distribution such that all values smaller than 0.5 are shown as blue and
all values larger than 0.5 in red/yellow. The offset also has the effect
that the vertices where we were unable to compute a value will now have a
value of exactly -0.5.

Then, the question becomes how to make tksurfer paint only the vertices
where we have a successfully computed value. After the shift, thresholding
will no longer work because it only operates on values around zero.

We have tried editing the .w file by both (i) removing the values from the
vertices that we do not want painted, and (ii) removing the vertices (the
entire line, vertex index plus value) from the file, but the tksurfer
brain surface window still shows an overlay with a value of 0 in these
vertices.

Thanks!

Tommi




---
Tommi Raij, M.D., Ph.D.
MGH/MIT/HMS Athinoula A. Martinos Center for Biomedical Imaging
Bldg 149, 13th St
Charlestown, MA 02129
U.S.A.
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