A method for segmenting an object in a volume image, executed at least in part on a computer, renders the volume image data to a two-dimensional display screen showing first, second, and third mutually orthogonal planes in the two-dimensional rendering. One or more operator instructions that identify a plurality of seed points on the rendered volume image are accepted. Two-dimensional coordinates of the identified seed points on the display screen are converted to three-dimensional seed-point coordinates relating to the first, second, and third mutually orthogonal planes a segmentation operation is performed on the volume image according to the converted three-dimensional seed-point coordinates. Segmentation results are displayed on the display screen, relative to the first, second, and third mutually orthogonal planes.