How can I stitch mosaics, like partial scans from a flatbad scanner of a large image?
PTGui was designed for stitching panoramas, from photographs taken from a single camera viewpoint. When stitching a panorama, images are warped to correct for perspective distortion so that a seamless overlap is achieved. For mosaic-style stitching on the other hand the images should only be shifted and rotated; any perspective warping is undesirable. PTGui can be tricked to do no warping by setting the field of view of the source images to a very small value, which corresponds to a tele lens with a long focal length. To stitch mosaics, proceed as follows: • Start a new project and load your source images • Switch PTGui to Advanced mode using the Advanced… button on the Project Assistant • Go to the Lens Settings tab and set the Lens type to Rectilinear. Set the Horizontal Field of View to 1 degree. • In the Control Points menu choose ‘Generate Control Points’ • Go to the Optimizer tab. Deselect the ‘Optimize lens Field of View’ checkbox. At ‘Minimize lens distortion’, choose ‘Heavy’
