An Optical Tracking System with Defaced Marker Detection

Abstract

Optical tracking systems (OTSs) have been widely used in clinical practice to fulfill the high precision needs of contemporary surgery. The markers that are defaced in the production or surgery reduce the accuracy and tracking range of OTS. This effect was not considered in current products from either industry or academia. In this paper, we propose an OTS which can detect the defaced markers automatically. A stereo camera module is set to track surgical instruments by locating the markers affixed to them. An adaptive threshold approach is suggested to locate the markers. The typical fiducial localization error of our OTS reaches 0.28 mm, which is totally comparable to commercial devices. A defaced marker detection method based on the luminous energy model of OTS is proposed and can be used to recognize the defaced markers regardless of their relative positions to the OTS.