1. A 3-dimensional rotational method for aligning a set of at least partially overlapping plural images to construct a mosaic image, comprising the following steps: for at least first and second images of said set of images, finding an incremental rotation of said second image relative to a 3-dimensional coordinate system tending to reduce registration error between overlapping portions of said first and second images; rotating said second image in accordance with said incremental rotation; and repeating said finding and rotating steps.