Real-time localization with vision only SLAM

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Hi, I am working on the implementation in an embedded system of a vision only SLAM algorithm. I have then to pick an algorithm ensuring efficiency and precison. I read about algorithms (EKF SLAM, FASTSLAM, GraphSLAM..) and i found that the literature contains so many approaches..For the EKF version, I found the approach of Davidson implementating a real-time EKF vision only SLAM..I wanna ask if there are approaches of graphslam or fastslam using only cameras (no odometry) and ensuring a real-time localization of a robot? Thank you for your help.