Visual Detection of Business Cards: Key-Point Correspondences Filtering

This study explores a coarse localization of a planar object using interest key-points and RANSAC algorithm. The method is employed as part of an application for the detection and recognition of a business card being waved in front of a camera. Localization follows the method of Vincent and Laganiere where RANSAC algorithm is used to find homography between two images that contain a dominant planar regions. RANSAC algorithm and a method for finding planar objects in two consecutive frames are presented in detail, with additional key-point stability over multiple frames being employed for the removal of background key-points. We evaluate the method on four business cards, two non-textured and two textured, and show to significantly reduce background key-points with the dominant planar object. We also show to completely remove background key-points when correspondences are matched on every fifth frame and when each key-point is required to be visible for at least 15 frames.