Without world-references, if your camera is not perfectly horizontal during the MAP INIT stage, there will be an angle between the absolute horizontal plane of the real-world and the computed horizontal plane shown inside the Dragonfly Web User Interface. This is normal because Dragonfly has no way to know exactly what is the real-world horizon. So Dragonfly assumes that the horizon is on the same horizontal axis as the horizontal axis of the camera during the MAP INIT phase.