Hi Kiersten

at its heart it is a region-growing algorithm followed by soap bubble smoothing. That is, the detected control points become fixed points in the soap bubble (which amounts to iterative averaging of all the non-fixed points). We use a Voronoi diagram to initialize the soap bubble for speed. There are lots of other things in it (e.g. robust histogramming, peak detection, outlier detection), but that is the core of it Bruce

On Mon, 22 Feb 2016, Kiersten Snyder wrote:

Hello,I am new to using Freesurfer and am currently using it for a biomedical image processing class. I am working on a project and would like to know the image processing technique behind the Control Points function.  Is it region growing, or what other process?

Thanks for the help! Kiersten