Motion estimation during photographing towards minimal solution for mobile panoramic images

초록

Panoramic images, which are often produced off-line a while after the photos are taken, might be all entertaining application if they were generated oil mobile devices immediately. Since producing a panorama requires feature extraction and matching that are expensive for mobile device, an embedded panoramic system needs for different approaches. Therefore, for on-line mobile panoramas, we propose methods that estimate camera motion during photographing and infer alignment based on motion so as to minimize computation time. A semi-automatic photographing method uses a guided user interface by showing a projected plane of the previously taken images and forces users to move the camera to the desired location. An automatic method keeps tracking the camera while the camera moves, estimates infinitesimal camera motions between neighbouring frames, accumulates motion fields, and therefore infers correspondences of far-away. The resulting motion information can be used for initializing, aligning, and stitching to produce a panorama on a pre-computed common plane. However, incorrect pivoting, lens fall-off or hand trembling may cause errors in stitching. So we apply a greedy local search to correct these errors. The complexity of the whole system is linear to the size of the images, and the running time is about 7 sec. for photographing and stitching four QVGA image on mobile devices.

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