A method for defining a three-dimensional surface of at least a portion of a patient's heart, based on data obtained by ultrasound imaging of the heart. The imaging is carried out over at least one cardiac cycle and provides a plurality of images in different image planes made with an ultrasound transducer at known positions and orientations. At least three anatomical landmarks in these images are manually identified in each of the images. An ultrasound mesh model in which a three-dimensional abstract mesh defining an archetype shape for a population of other hearts is developed. This abstract mesh has associated with it a covariance that defines the extent of variation of control vertices in the mesh for the population of training data used to derive the mesh model. The mesh model is rigidly aligned with the images of the patient's heart. Predicted images in planes corresponding to those of the images for the patient's heart and derived from the mesh model are compared corresponding images of the patient's heart. Control vertices are included with the abstract mesh for reiteratively adjusting a shape of the mesh model to optimize the fit of the predicted images to the observed images of the patient's heart. This adjustment and comparison continues until an acceptable fit is obtained, yielding an output that defines the shape of the endocardium and epicardium of the left ventricle or other portion of the patient's heart, in three dimensions, for use in determining cardiac parameters.