Thank you Bruce. I can load it as patch as you suggested. I can also load the curvatures to color it. Thus I imagine in the data, there would be 2D locations of the vertices, and their indices respect to the full surface. Is it true? How can I read this information (e.g. into matlab) ? 
Thanks again! Also thanks to anyone who would like to comment!

best
Peng 


On Fri, May 9, 2014 at 5:12 PM, Bruce Fischl <fischl@nmr.mgh.harvard.edu> wrote:
Hi Peng

the flat maps are stored in a different format than the surfaces, called a "patch" format (since they are only a piece of the whole surface - not the entire thing). You can load them with file->load patch in tksurfer. Not sure about freeview, perhaps Ruopeng can comment?

cheers
Bruce


On Fri, 9 May 2014, peng wrote:


More information, error from tksurfer is as following:

========================
MRISalloc(16711682, 480): could not allocate vertices
Cannot allocate memory
============


---------- Forwarded message ----------

From: peng <prion.w@gmail.com>
Date: Fri, May 9, 2014 at 1:01 PM
Subject: a question on flat surface
To: "Freesurfer@nmr.mgh.harvard.edu" <freesurfer@nmr.mgh.harvard.edu>


Hi Freesurfers,
   I have tried to obtain a flat surface as described by the upper part
(full cortex) of the following page:

   http://freesurfer.net/fswiki/FreeSurferOccipitalFlattenedPatch

   However, I failed to load the results in freeview (it took forever), nor
can I read in matlab with read_surf. The error in matlab is as following 
======
Error using reshape
To RESHAPE the number of elements must not change.

Error in read_surf (line 77)
vertex_coords = reshape(vertex_coords, 3, vnum)' ;
======
   Thus I suspect in the newly generated surface, the number of vertices in
the header does not meet that indicated by the data. I did sth wrong.

Questions:
1 Is this webpage still up-to-date or I shall try something new to flatten
the surface?
2 Probably there are "frequently made mistakes" during my manual process,
would you please give me a hint? I my case afterwards mris_flatten took 2-3
hours.

btw: the inflated surface is OK either checked by freeview or matlab.

best
Peng



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