Fig. 1. Magnetometer ellipsoid calibration

Fig. 2. Vector diagram of any location on earth

Fig. 3. Framework of visual/inertial/geomagnetic information tightly coupled positioning system

Fig. 4. Structure of visual/inertial/geomagnetic optimization factor graph

Fig. 5. Vision/inertial/geomagnetic sensor fusion positioning experimental platform

Fig. 6. Measurement of magnetic field change curve in experimental environment

Fig. 7. Operation trajectory and absolute position error （Experiment 1）

Fig. 8. Operation trajectory and absolute position error （Experiment 2）

Fig. 9. Operation trajectory and absolute position error （Experiment 3）

Fig. 10. Comparison of non adaptive fusion schemes