1. A method comprising: by a medical-imaging digital-computing processor: the processor accessing a memory to obtain a plurality of data objects, wherein at least some of the data objects each comprises a medical image that pertains to portions of human anatomy; the processor executing an iterative medical-imaging process that comprises starting with an initial approximation and cycling through a series of successive approximations to test for a better solution to determine at least one of: a labeling of a portion of one of the data objects; and a geometric relationship between at least portions of at least two of the data objects; by, at least in part: the processor automatically employing both a segmentation module and a registration module as steps within the iterative process by, at least in part, automatically selecting between employing the segmentation module and the registration module during a given iteration of the iterative process, wherein the segmentation module and the registration module are separate modules from one another and during the given iteration either the segmentation module or the registration module is employed, but not both; and the processor determining when to automatically generate an intermediate data object having a form that is compatible with the selected module to provide as input to at least one of the segmentation module and the registration selected module.