1. A method of detecting an anatomical primitive in an image volume, the method comprising: detecting a plurality of tranformationally invariant points (TIPs) in the volume; aligning the volume using the TIPs; detecting a plurality of landmark points in the aligned volume that are indicative of a given anatomical object; and fitting a target geometric primitive as the anatomical primitive using the detected landmark points, wherein the method is performed by a processor, wherein the fitting comprises: for a predetermined plurality of tries, randomly sampling points of the landmark points to fit a geometric primitive using a least squares method; refining the geometric primitive and generating a corresponding error using an iteratively re-weighted least squares (IRLS) method; and selecting one of the refined geometric primitives as the anatomical primitive based on the corresponding errors.