Feature Extraction and Calibration for Stereo Reconstruction Using Non-SVP Optics in a Panoramic Stereo-Vision Sensor

  • Authors:
  • Mark Fiala;Anup Basu

  • Affiliations:
  • -;-

  • Venue:
  • OMNIVIS '02 Proceedings of the Third Workshop on Omnidirectional Vision
  • Year:
  • 2002

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Abstract

Omni-directional sensors are useful in obtaining a 360°field of view with a single lens camera. Omni-directionalstereo imaging systems were designed in our past researchusing a single camera and a mirror consisting of two concentric,radially symmetric lobes. If the central camera-mirroraxis is vertical, a stereo image containing imageryfrom all azimuth directions from two viewpoints can be capturedwithin one image.A vertically posed catadioptric optical system that employsa mirror with a radial profile other than parabolicor hyperbolic cannot maintain the straightness of any nonverticallines. However other mirror profiles are desirablefor resolution distribution, sensor size and manufacturability.These other mirror shapes, including spherical mirrors,are said to be non-SVP (Single View-Point). Since they lacka virtual perspective point, they pose new feature extractionchallenges.A method for processing the imagery from a panoramicnon-SVP catadioptric stereo sensor to reconstruct a three-dimensionalmodel of horizontal and vertical line featuresis introduced. Horizontal line segments are extracted usingthe Panoramic Hough Transform and vertical line segmentsare recognized as straight radial lines. These segments, andclosed shapes they form are matched between the two lobeviews to locate them in three-dimensions.The practical accuracy obtainable with such a systemwas explored, and some of the issues addressed to makethis sensor work in real 3D reconstructions are described.Triangulating a 3D location requires better calibration informationthan is required for the robust feature extraction.Experimental results with synthetic and real images arepresented to validate this model.