Continuous Zoom Calibration by Tracking Salient Points in Endoscopic Video

  • Miguel Lourenço
  • João P. Barreto
  • Fernando Fonseca
  • Hélder Ferreira
  • Rui M. Duarte
  • Jorge Correia-Pinto
Part of the Lecture Notes in Computer Science book series (LNCS, volume 8673)


Many image-based systems for aiding the surgeon during minimally invasive surgery require the endoscopic camera to be calibrated at all times. This article proposes a method for accomplishing this goal whenever the camera has optical zoom and the focal length changes during the procedure. Our solution for online calibration builds on recent developments in tracking salient points using differential image alignment, is well suited for continuous operation, and makes no assumptions about the camera motion or scene rigidity. Experimental validation using both a phantom model and in vivo data shows that the method enables accurate estimation of focal length when the zoom varies, avoiding the need to explicitly recalibrate during surgery. To the best of our knowledge this the first work proposing a practical solution for online zoom calibration in the operation room.


Focal Length Camera Motion Camera Calibration Boundary Contour Distortion Parameter 
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Copyright information

© Springer International Publishing Switzerland 2014

Authors and Affiliations

  • Miguel Lourenço
    • 1
  • João P. Barreto
    • 1
    • 2
  • Fernando Fonseca
    • 3
  • Hélder Ferreira
    • 4
  • Rui M. Duarte
    • 4
  • Jorge Correia-Pinto
    • 4
  1. 1.Institute of Systems and RoboticsUniversity of CoimbraCoimbraPortugal
  2. 2.Perceive 3DCoimbraPortugal
  3. 3.Faculty of MedicineCoimbra Hospital and Universitary CentreCoimbraPortugal
  4. 4.Life and Health Sciences Research InstituteUniversity of MinhoBragaPortugal

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