Sorry that I did not make it claer. The resampling did not fail, just the result was not good.
The resamping process is like this:
I treated reconstructed cortical surfaces as functions defined on a sphere. Meanwhile, I divided a sphere into 163842 points and 300,000+ triangles by iteratively subdividing a icosahedron for 7 times. I would like to compute the spatial coordinates of the 163842 points in R^3 space and then get a resampled cortical surface. To achieve this, I linearly interpolated the 163842 points on the ?h.sphere.reg files and computed their spatial positions.
The problem is that after spherical registration, the triangles on ?h.sphere.reg became more unevenly distributed(or distorted) -- some of them had very small areas. Thus the 163842 points which were evenly spread on the sphere may not resample all the details of the cortical surface. In my case, some resampled triangles were too large that some sulci disappeared. I hope that changing the default average surface of mris_register may fix the problem...
Thanks.
----- Original Message ----- From: "Bruce Fischl" fischl@nmr.mgh.harvard.edu To: "Jiefeng Jiang" jfjiang@nlpr.ia.ac.cn Cc: freesurfer@nmr.mgh.harvard.edu Sent: Thursday, September 20, 2007 7:45 PM Subject: Re: [Freesurfer] Average surface of mris_register
I'm sorry, I don't understand. What resampling fails? How does it fail?
On Thu, 20 Sep 2007, Jiefeng Jiang wrote:
Hi,
I am using the ?h.sphere.reg files automatically generated by reconall. However, I found that the area distortion compromise the results of my following resample step. I wonder whether replacing the default average surface "$FREESURFER_HOME/average/?h.average.curvature.filled.buckner40.tif" with the ?h.sphere in the /average/surf directory would reduce the distortion. If so, could anyone tell me how to get a .tif file using files in /average/surf directory?
Thank you!