[Freesurfer] distance between two vertices in Freeview

Dear Freesurfer experts

Hi

I was trying to measure the dimensions of a surface ROI in a flatten map on Freeview. I used the 3D scale bar to measure the longest diameter of the ROI. My question is how the scale bar is calculating the distance between the two points? Is it the euclidean distance between the two vertices? I calculated the euclidean distance in matlab between the two vertices (using their x and y coordinates) , and the number I get, is much higher than what I see in freeview. I wonder why this discrepancy is happening?

I appreciate if you could please let me know the answer to my question.

Thanks MOna

Zahra (Mona) Nasiriavanaki, M.D. Postdoctoral Research Fellow Department of Psychiatry Massachusetts General Hospital 149 13th Street, 149-2615 Charlestown, MA, USA, 02129