Active Stereo: Integrating Disparity, Vergence, Focus, Aperture, and Calibration for Surface Estimation

Narendra Ahuja, A. Lynn Abbott

Research output: Contribution to journalArticlepeer-review


Much research has emphasized stereo disparity as a source of depth information. To a lesser extent, camera vergence and lens focus have also been investigated for their utility in depth recovery. Each of these visual cues exhibits shortcomings when used individually in the sense that none alone can be used to reconstruct surfaces for real scenes that often cover a wide field of view and a large range of depth. This paper presents an approach to integration of these cues that attempts to exploit their complementary strengths and weaknesses through active control of camera focus and orientations. In addition, the aperture and zoom settings of the cameras are controlled. The result is an active vision system that dynamically and cooperatively interleaves image acquisition with surface estimation. A dense composite map of a single contiguous surface is synthesized by automatically scanning the surface and combining estimates of adjacent, local surface patches. This problem is formulated as one of minimizing a pair of objective functions. The first such function is concerned with the selection of a target for fixation. The second objective function guides the surface estimation process in the vicinity of the fixation point. Calibration parameters of the cameras are treated as variables during optimization, thus making camera calibration an integral, flexible component of surface estimation. An implementation of this method is described, and a performance evaluation of the system is presented. An average absolute error of less than 0.15% in estimated depth was achieved for a large surface having a depth of approximately 2 m.

Original languageEnglish (US)
Pages (from-to)1007-1029
Number of pages23
JournalIEEE transactions on pattern analysis and machine intelligence
Issue number10
StatePublished - Oct 1993


  • Active vision
  • camera calibration
  • fixation
  • from focus
  • range
  • range from stereo
  • range from vergence
  • surface estimation
  • visual cue integration
  • visual target selection

ASJC Scopus subject areas

  • Software
  • Computer Vision and Pattern Recognition
  • Computational Theory and Mathematics
  • Artificial Intelligence
  • Applied Mathematics


Dive into the research topics of 'Active Stereo: Integrating Disparity, Vergence, Focus, Aperture, and Calibration for Surface Estimation'. Together they form a unique fingerprint.

Cite this