Continuous zoom calibration by tracking salient points in endoscopic video

Area of Science:

• Medical Imaging
• Surgical Technology
• Computer Vision

Background:

• Image-based surgical systems require constant camera calibration.
• Endoscopic cameras in minimally invasive surgery often feature optical zoom.
• Focal length changes during procedures necessitate recalibration, disrupting surgery.

Purpose of the Study:

• To propose a practical method for online calibration of endoscopic cameras with optical zoom.
• To enable continuous focal length estimation during surgical procedures.
• To eliminate the need for manual recalibration during surgery.

Main Methods:

• Utilizes differential image alignment for tracking salient points.
• Designed for continuous operation without assumptions on camera motion or scene rigidity.
• Employs an online calibration approach for dynamic focal length adjustments.

Main Results:

• Accurate estimation of focal length with varying zoom levels was achieved.
• Experimental validation performed using both phantom models and in vivo data.
• The method successfully avoided the need for explicit recalibration during simulated surgery.

Conclusions:

• Presents the first practical solution for online zoom calibration in the operating room.
• Enhances the reliability and efficiency of image-guided minimally invasive surgery.
• Facilitates uninterrupted surgical procedures by maintaining camera calibration.