1. A method for constructing a composite image of a subject, the method comprising: calibrating an imaging device to said subject, said calibrating including comparing characteristics of a reference image of said subject with corresponding characteristics of said subject as imaged by said imagining device, mapping the position of said imaging device to a known position on said subject and computing a slant angle, wherein said imaging device images a portion of said subject at a time; changing in discrete position steps the imaging position of said imaging device relative to said subject to span said subject in a step-by-step fashion, and implementing the following sub-steps at each discrete position step: (a) capturing a current snapshot of the portion of said subject currently imaged by said imaging device at the current discrete position step; (b) determining a first set of feature points within the current snapshot and a second set of feature points within its corresponding portion in said reference image; (c) identifying corresponding feature points within said first and second sets of feature points; (d) determining the affine angle of the identified corresponding feature points; and (e) IF the magnitude of said affine angle is greater than a predefined maximum affine angle, THEN making a position adjustment of said imaging device relative to said subject that is smaller than said discrete position steps, capturing a current snapshot of the portion of said subject corresponding to the position adjustment, and returning to sub-step (b); and (f) storing and registering the snapshot of said subject corresponding to the current discrete position step.