minimum points of 3D plot and computing a plane through

Hello All,

In the image '3d points plot', I have my 3d point plot of my 3D shape, and I would like to compute the same as what is presented in the image 'plane in lowest points'. Which is determining the plane that is passing through the lowest points of this plot (which are the small red points in the image of which the plane is drawn).

The question then, how I can determine the minimum points of my 3d points, and after compute a plane passing through them?

Hope someone give an answer.

Thank you in advance.