  The next generation of Mars rotorcrafts requires on-board autonomous hazard
avoidance landing. To this end, this work proposes a system that performs
continuous multi-resolution height map reconstruction and safe landing spot
detection. Structure-from-Motion measurements are aggregated in a pyramid
structure using a novel Optimal Mixture of Gaussians formulation that provides
a comprehensive uncertainty model. Our multiresolution pyramid is built more
efficiently and accurately than past work by decoupling pyramid filling from
the measurement updates of different resolutions. To detect the safest landing
location, after an optimized hazard segmentation, we use a mean shift algorithm
on multiple distance transform peaks to account for terrain roughness and
uncertainty. The benefits of our contributions are evaluated on real and
synthetic flight data.
