1. A computer-implemented method comprising: capturing a plurality of surface registration points of a portion of an organ from (i) an ultrasound image of the portion of the organ acquired by a catheter from within an anatomical structure in a patient's body; and (ii) data regarding the position of the catheter when the ultrasound image was acquired; and registering a portion of a 4D model of the organ with the plurality of surface registration points by: applying a rigid global registration; and applying a local, free-form, non-rigid registration.