Photo Tourism's Section 4, running here rather than on a server. Drop in photographs of one subject taken from different positions, and this will find keypoints, match every pair, check each pair against an epipolar geometry, join the matches into tracks, place the cameras one at a time and bundle adjust them. What comes out opens in the same explorer as the book's own scenes.
Nothing is uploaded. The photographs are decoded, measured and discarded in this tab, and closing it takes the reconstruction with it. Two things it does not do: the focal length is a guess at a 50 degree field of view unless a photograph carries one, and no lens distortion is estimated. Transitions stand on the plane two cameras share rather than on a homography measured between them, which on the book's own scenes costs about one per cent of the photograph's diagonal.