Stereo-image registration and change detection system and method

A method for detecting differences in a photographed scenery between two time points, the method comprising:

• a) obtaining at least two sets of stereoscopic images, each one of said at least two sets including images that are taken from different angles, each one of said at least two sets including images taken at different time with respect to the images of the other sets;
• b) determining at least two groups of images, each one of said groups including at least two images of at least two of said sets or are derived from images of said sets;
• and
• c) for each one of said groups, calculating a respective optimal entities list including:
• i) registering at least two images of said group giving rise to registered images;
• ii) detecting changes between the registered images thereby giving rise to a candidate entities list;
• and
• iii) selecting at least four optimal entities from said candidate entities list in accordance with at least one selection criterion, thereby giving rise to said optimal entities list;
• d) stereo-matching at least two images, each one being or derived from different one of said at least two groups and same or different sets, using at least four optimal entities from each one of said optimal entities list giving rise to at least one pair of registered stereoscopic images;
• e) producing depth maps for at least two of said pairs of registered stereoscopic images;
• and
• f) calculating height differences between corresponding regions of said depth maps;
• whereby volumetric differences are detected between said sets of stereoscopic images.

A system for producing tie points for use in stereo-matching of stereoscopic images, the system comprising:

• a processor and associated storage, said processor and associated storage are configured to perform at least the following:
• a) obtain at least two sets of stereoscopic images, each one of said at least two sets including images that are taken from different angles, each one of said at least two sets including images taken at different time with respect to the images of the other sets;
• b) determine at least two groups of images, each group including at least two images of at least two of said sets or are derived from images of said sets;
• and
• c) for each one of said groups, calculate a respective optimal entities list including:
• i) registering at least two images of said group giving rise to registered images;
• ii) detecting changes between the registered images thereby giving rise to a candidate entities list;
• and
• iii) selecting at least four optimal entities from said candidate entities list in accordance with at least one selection criterion, thereby giving rise to said optimal entities list;
• whereby entities of the optimal entity lists are used as tie points for stereo-matching at least two images, each one being or derived from different one of said at least two groups thereby giving rise to at least one pair of stereo-matched stereoscopic images.

A program storage device readable by machine, tangibly embodying a program of instructions executable by the machine to perform method operations for producing tie points for use in registering stereo-matching of stereoscopic images, said method comprising:

• a) obtaining at least two sets of stereoscopic images, each one of said at least two sets including images that are taken from different angles, each one of said at least two sets including images taken at different time with respect to the images of the other sets;
• b) determining at least two groups of images, each one of said groups including at least two images of at least two of said sets or are derived from images of said sets;
• and
• c) for each one of said groups, calculating a respective optimal entities list including:
• i) registering at least two images of said group giving rise to registered images;
• ii) detecting changes between the registered images thereby giving rise to a candidate entities list;
• and
• iii) selecting at least four optimal entities from said candidate entities list in accordance with at least one selection criterion, thereby giving rise to said optimal entities list;
• whereby entities of the optimal entity lists are used as tie points for stereo-matching at least two images, each one being or derived from different one of said at least two groups thereby giving rise to at least one pair of stereo-matched stereoscopic images.

A method for producing tie points for use in stereo-matching of stereoscopic images, the method comprising:

• 1) registering at least two pairs of images that include a common target, the images in each pair taken from substantially same angle unique for each pair, and each pair including images taken at different time points;
• 2) for each one of the registered pairs, calculating an optimal entities list by:
• i) detecting changes between images of the registered pair thereby giving rise to a candidate entities list;
• and
• ii) selecting at least four optimal entities from said candidate entities list in accordance with at least one selection criterion, thereby giving rise to said optimal entities list;
• whereby the optimal entities lists are used as tie points for stereo-matching at least two images, each one being or derived from different one of the registered pairs.