Vision based navigation has been widely accepted as a promising approach to obtain position and orientation information in GNSS-denied environments.However,due to the complexity of such environment,a number of factors such as keypoint mismatch may pose faults for the navigation solution,deteriorating navigation performance.Hence fault detection and isolation is a necessary step to improve the reliability of such system.Further,multiplefaults assumption is more realistic and general than single-fault assumption.However,the systems ability to detect and separate potential faults is one critical aspect.In this paper,reliability and separability in both single-fault and multiple-fault case of visual navigation using reality-based 3D maps is comprehensively analyzed through real data from indoor environment.The analysis demonstrates that geometry has an important impact on reliability and separability in both single-fault and multiple-fault scenarios.The better geometry will enhance reliability and separability of the visual navigation system.