New Interactive Methods for Image Registration with Applications in Repeat Photography

ABSTRACTWe present two methods to interactively register images, which can not be registered automatically due to the large differences between them. Those difference may occur with images which are multitemporal, multisensory, or multipositional. Our methods are used to register repeat photography compilations consisting of a historic image and a contemporary image of the same scene. Method I iteratively computes a rigid transformation registering the two images based on user added point pairs. More complex transformations are generated with more added point pairs starting from a translation with one point pair to an optimized perspective transformation with more than four user added point pairs. Method II allows users to grab and drag one of the images to be registered and pin it to the second image. Depending on the number of positions at which the images are pinned together more complex transformations are computed. Further we present a third method aiding already at the creation of the second image. Method III allows the user to compare a life camera stream (e.g. from a smartphone camera or webcam) with a first image using different composition forms such allowing users to check if they reached the camera position of the first image. All methods give direct feedback to the user during the registration process and run on client side on a web browser without additional software. Further, they are planned to be integrated into our repeat photography web portal.