Multi-modal image registration for localization in Titan´s atmosphere

We study the problem of localizing a balloon in the atmosphere of Saturn´s moon Titan by registering onboard imagery with orbital imagery. This is critical for both autonomous navigation purposes and acquisition and sampling of scientifically interesting sites. Because of Titan´s atmospheric opacity, we require the ability to match combinations of visible, infrared (IR) and synthetic aperture radar (SAR) images. For both localization and direct use as a multi-modal data product for science analysis, match results must be sub-pixel accurate. We demonstrate the feasibility of matching orbital SAR data to visible and IR imagery and outline a framework for using this data as a navigation product. We demonstrate a technique to compensate for local distortions to enable accurate data registration in spite of differences in sensor return and imaging geometry. Finally, we show match results using both terrestrial imagery and the limited amount of available Titan data acquired by the Cassini orbiter and Huygens probe.