Human localization is an enabling technology for many mobile applications. As more and more people carry mobile phones with them, we can now localize a person by localizing his mobile phone. However, it is observed that presence of human bodies introduces heavy interference to mobile phone signals. This has been one of the major causes of inaccurate wireless localization for humans. In this paper, we propose using video cameras to help estimate human body's interference on mobile device's signals. We combine human orientation detection and human/phone/AP relative position inference estimation to better measure how a human blocks or reflects wireless signals. We have also developed a signal distortion compensation model. Based on these technologies, we have implemented a human localization system called EV-Human. Real world experiments show that our EV-system can accurately and robustly localize humans. © 2013 IEEE.