Fig. 1. Schematic of markerless registration method

Fig. 2. Flow chart of head point cloud extraction algorithm

Fig. 3. Preoperative preparation work

Fig. 4. Hand-eye calibration schematic

Fig. 5. Coordinate transformation in registration

Fig. 6. Experimental setup. (a) Operation platform; (b) optical tracking system

Fig. 7. Position of landmark of phantom model

Fig. 8. Diagram of Dice calculation

Fig. 9. Experiment of target registration error. (a) Obtaining maker position of real model; (b) obtaining marker position of virtual model

Fig. 10. Target registration error and Dice in 10 times experiment

Fig. 11. Marker registration error