Hi Ting

STL may not contain the info for ras2vox transform as it is not a medical imaging format. We've only supported it in the past for 3D printing and such. You might need to keep track of the ras2vox and restore it when you convert back (e.g. in matlab)

cheers Bruce

On Fri, 21 Nov 2014, ting xu wrote:

Hi there,

In my understanding, mris_convert does not change any information (vertices coordinates and triangles) during converting, right? However, I observed odd thing as bellow,

Command I used: mris_convert subjid/surf/lh.white subjid/surf/lh.white.stl

I convert the white surface to .stl format, then load original white surface and .stl file in freeview, with subjid/mri/brainmask.mgz as volume underlay. The shape of lh.white.stl mesh looks the same as original one, but the position of lh.white.stl was displaced. I attached a screenshot (yellow one is original white surface, red one is .stl format one).

I also used freesurfer_read_surf function to read the coordinates and the faces in matlab, then compare it to .stl coordinate, they are the same.

I need to use .stl format for my analysis outside freesurfer, then convert result back to freesurfer format. I am worried whether this would cause any problems?

PS, if it is fsaverage template surface, no position shift after format transform.

Many thanks if anyone help with this,

Ting