A Mobile Camera Localization Method Using Aerial-View Images

This paper proposes a method to localize a mobile camera by searching corresponding points between the mobile camera image and aerial images yielded by GIS database. A same object differently appears in the two images, because the mobile camera images are taken from the user´s viewpoints (i.e., on the ground), and aerial images from much higher viewpoints. To reduce such differences in appearance, the mobile camera image is transformed into a virtual top-view image by using the gravity information given by an inertia sensor embedded in the mobile camera. The SIFT algorithm is applied to find corresponding points between the virtual top-view and the aerial images. As the result, a homography matrix that transforms the virtual top-view image into the aerial image is obtained. By using the matrix, the position and orientation of mobile camera are estimated. If the textural information about ground region captured by the mobile camera is poor, it is difficult to obtain a sufficient number of correct corresponding points to allow an accurate homography matrix to be calculated. To deal with such cases, we develop an optional process that stitches multiple virtual top-view images together to cover a larger region of the ground. Experimental evaluation is conducted by a developed pilot system.