Before revision:  We extensively evaluate the proposed system on simulation and real-world experiments, and the result demonstrates that our system substantially eliminates the drift of VIO and preserves the  accuracy in spite of noisy GNSS measurements  .
After revision:  We extensively evaluate the proposed system on simulation and real-world experiments, and the result demonstrates that our system substantially eliminates the drift of VIO and preserves the accuracy in spite of noisy GNSS measurements . In addition, experiments also show that our system can gain from even a single satellite while conventional GNSS algorithms need four at lease .