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Calibration of a surgical microscope with automated zoom lenses using an active optical tracker
Author(s) -
García Jaime,
Thoranaghatte Ramesh,
Marti Gaetan,
Zheng Guoyan,
Caversaccio Marco,
González Ballester Miguel A.
Publication year - 2008
Publication title -
the international journal of medical robotics and computer assisted surgery
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.556
H-Index - 53
eISSN - 1478-596X
pISSN - 1478-5951
DOI - 10.1002/rcs.180
Subject(s) - zoom , computer science , computer vision , artificial intelligence , calibration , microscope , transformation (genetics) , focus (optics) , augmented reality , optics , physics , biochemistry , chemistry , quantum mechanics , gene , lens (geology)
Background In this paper, we present a new method for the calibration of a microscope and its registration using an active optical tracker. Methods Practically, both operations are done simultaneously by moving an active optical marker within the field of view of the two devices. The IR LEDs composing the marker are first segmented from the microscope images. By knowing their corresponding three‐dimensional (3D) position in the optical tracker reference system, it is possible to find the transformation matrix between the referential of the two devices. Registration and calibration parameters can be extracted directly from that transformation. In addition, since the zoom and focus can be modified by the surgeon during the operation, we propose a spline based method to update the camera model to the new setup. Results The proposed technique is currently being used in an augmented reality system for image‐guided surgery in the fields of ear, nose and throat (ENT) and craniomaxillofacial surgeries. Conclusions The results have proved to be accurate and the technique is a fast, dynamic and reliable way to calibrate and register the two devices in an OR environment. Copyright © 2008 John Wiley & Sons, Ltd.