Abstract
It is known that a set of points in three-dimensions is determined up to projectivity from two views with uncalibrated cameras. It is shown in this paper that this result may be improved by distinguishing between points in front of and behind the camera. Any point that lies in an image must lie in front of the camera producing that image. Using this idea, it is shown that the scene is determined from two views up to a more restricted class of mappings known as quasi-affine transformations, which are precisely those projectivities that preserve the convex hull of an object of interest. An invariant of quasi-affine transformation known as the chiral sequence of a set of points is defined and it is shown how the chiral sequence may be computed using two uncalibrated views. As demonstrated theoretically and by experiment the chiral sequence may distinguish between sets of points that are projectively equivalent. These results lead to necessary and sufficient conditions for a set of corresponding pixels in two images to be realizable as the images of a set of points in three dimensions.Using similar methods, a necessary and sufficient condition is given for the orientation of a set of points to be determined by two views. If the perspective centres are not separated from the point set by a plane, then the orientation of the set of points is determined from two views.
Similar content being viewed by others
References
Faugeras, O.D. 1992. What can be seen in three dimensions with an uncalibrated stereo rig? Computer Vision-ECCV' 92, LNCS-Series Vol. 588,Springer-Verlag, pp. 563-578.
Hartley, R. 1992. Invariants of points seen in multiple images. Unpublished report.
Hartley, R.I. 1993a. Invariants of lines in space. In Proc. DARPA Image Understanding Workshop, pp. 737-744.
Hartley, R.I. 1993b. Euclidean reconstruction from uncalibrated views. In Proc. of the Second Europe-US Workshop on Invariance, Ponta Delgada, Azores, pp. 187-202.
Hartley, R.I. and Kawauchi, A. 1979. Polynomials of amphicheiral knots. Math. Ann., 243:63-70.
Hartley, R., Gupta, R. and Chang, T. 1992. Stereo from uncalibrated cameras. In Proc. IEEE Conf. on Computer Vision and Pattern Recognition, pp. 761-764.
Longuet-Higgins, H.C. 1981. A computer algorithm for reconstructing a scene from two projections. Nature, 293:133-135.
Mohr, R., Veillon, F., and Quan, L. 1993. Relative 3D reconstruction using multiple uncalibrated images. In Proc. IEEE Conf. on Computer Vision and Pattern Recognition, pp. 543-548.
Morin, L. 1993. Quelques Contributions des Invariants Projectifs À la Vision par Ordinateur. Ph.D. Thesis, Institut National Polytechnique de Grenoble.
Morin, L., Brand, P., and Mohr, R., 1995. Indexing with projective invariants. In Proceedings of the Syntactical and Structural Pattern Recognition Workshop, Nahariya, Israel. World Scientific Pub.
Press, W.H., Flannery, B.P., Teukolsky, S.A., and Vetterling, W.T. 1988. Numerical Recipes in C: The Art of Scientific Computing, CambridgeUniversity Press.
Robert, L. and Faugeras, O.D. 1993. Relative 3D positioning and 3D convex hull computation from a weakly calibrated stereo pair. In Proc. International Conference on Computer Vision, pp. 540-544.
Rothwell, C.A., Zisserman, A., Forsyth, D.A., and Mundy, J.L. 1992. Canonical frames for planar object recognition. In Computer Vision-ECCV' 92, LNCS-Series Vol. 588, Springer-Verlag, pp. 757-772.
Sparr, G., 1992. Depth computations from polyhedral images. In Computer Vision-ECCV' 92, LNCS-Series Vol. 588, Springer-Verlag, pp. 378-386.
Sutherland, I.E. 1980. Sketchpad: A man-machine graphical communications system. Technical Report 296, MIT Lincoln Laboratories, 1963. Also published by Garland Publishing Inc., New York.
Wolfram, S. 1988. Mathematica: A System for Doing Mathematics by Computer. Addison-Wesley: Redwood City, California.
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Hartley, R.I. Chirality. International Journal of Computer Vision 26, 41–61 (1998). https://doi.org/10.1023/A:1007984508483
Issue Date:
DOI: https://doi.org/10.1023/A:1007984508483