  Rover localization is one of the perquisites for large scale rover
exploration. In NASA's Mars 2020 mission, the Ingenuity helicopter is carried
together with the rover, which is capable of obtaining high-resolution imagery
of Mars terrain, and it is possible to perform localization based on
aerial-to-ground (A2G) imagery correspondence. However, considering the
low-texture nature of the Mars terrain, and large perspective changes between
UAV and rover imagery, traditional image matching methods will struggle to
obtain valid image correspondence. In this paper we propose a novel pipeline
for Mars rover localization. An algorithm combing image-based rock detection
and rock distribution pattern matching is used to acquire A2G imagery
correspondence, thus establishing the rover position in a UAV-generated ground
map. Feasibility of this method is evaluated on sample data from a Mars
analogue environment. The proposed method can serve as a reliable assist in
future Mars missions.
