1. A method of relating local topographical data maps of a test object with a digital image processing system for forming a composite global topographical data map corresponding to an assembly of the local topographical data maps of the test object, comprising steps of: forming a plurality of local topographical data maps containing respective sets of values corresponding to surface height measurements of a test object taken by a digital imaging device of the digital image processing system over different portions of the test object; evaluating overlapping regions of the local topographical data maps to define a plurality of difference maps containing values based on differences between the surface height measurements of the test object taken over common portions of the test object; fitting a set of parameters to the difference maps to quantify initial differences between the overlapping regions of the local topographical data maps; defining a corresponding set of parameters that can be varied in value for altering orientations of the local topographical data maps; determining new values for the parameters of the local topographical data maps that satisfy a merit function incorporating the parameter values of the difference maps; and stitching the local topographical data maps together within the digital image processing system in accordance with the new parameter values of the local topographical data maps that satisfy the merit function producing a composite global topographical data map containing values corresponding to surface height measurements over a plurality of the local areas of the test object.