Methods and systems provide improved navigation through tubular networks such as lung airways by providing improved estimation of location and orientation information of a medical instrument (e.g., an endoscope) within the tubular network. Various input data such as image data and CT data, are used to model the tubular networks, and the model information is used to generate a camera pose representing a specific site location within the tubular network and/or to determine navigation information including position and orientation for the medical instrument.