DeltaViewer is an application program for Apple Macintosh. DeltaViewer reads in a sequence of cross sectional images of an object like those obtained by confocal laser microscopes, CT, MRI, optical microscopes, and electron microscopes. It then computationally reconstructs the surface of the object, and shows it on computer display. The image on the screen can then be freely rotated by mouse, so that one can easily recognize the 3-dimansional shapes of the objects and their spatial relationships.