In one embodiment, a method comprising, receiving a three-dimensional map of one or more obstructions associated with a field, the one or more obstructions presenting an obstacle to line of sight reception from a satellite to a global navigation satellite systems (GNSS) receiver； receiving almanac data corresponding to an orbit of the satellite； determining anticipated accuracy of positioning in the field at plural locations and plural times based on the almanac data and the map； and determining waylines for autonomous traversal through the field based on the anticipated accuracy at the plural locations and the plural times.
