{ "id": "1202.1303", "version": "v2", "published": "2012-02-06T21:43:33.000Z", "updated": "2013-03-15T14:00:55.000Z", "title": "Object-image correspondence for curves under projections", "authors": [ "Joseph M. Burdis", "Irina A. Kogan" ], "comment": "A significantly improved version of this paper (corrected and completed) has been posted arXiv:1303.3358", "categories": [ "math.AG", "cs.CG" ], "abstract": "We present a novel algorithm for deciding whether a given planar curve is an image of a given spatial curve, obtained by a central or a parallel projection with unknown parameters. A straightforward approach to this problem consists of setting up a system of conditions on the projection parameters and then checking whether or not this system has a solution. The main advantage of the algorithm presented here, in comparison to algorithms based on the straightforward approach, lies in a significant reduction of a number of real parameters that need to be eliminated in order to establish existence or non-existence of a projection that maps a given spatial curve to a given planar curve. Our algorithm is based on projection criteria that reduce the projection problem to a certain modification of the equivalence problem of planar curves under affine and projective transformations. The latter problem is then solved by differential signature construction based on Cartan's moving frame method. A similar approach can be used to decide whether a given finite set of ordered points on a plane is an image of a given finite set of ordered points in R^3. The motivation comes from the problem of establishing a correspondence between an object and an image, taken by a camera with unknown position and parameters.", "revisions": [ { "version": "v2", "updated": "2013-03-15T14:00:55.000Z" } ], "analyses": { "subjects": [ "14H50", "14Q05", "68T45", "03C10" ], "keywords": [ "object-image correspondence", "planar curve", "spatial curve", "finite set", "straightforward approach" ], "note": { "typesetting": "TeX", "pages": 0, "language": "en", "license": "arXiv", "status": "editable", "adsabs": "2012arXiv1202.1303B" } } }