A mobile device adjusts the extents to which it depends on various satellites to estimate its global position based on the predicted probability for each such satellite that a ray extending from that satellite to the mobile device is obstructed by a building. The mobile device can predict the probabilities of building obstructions based on a digital model of the environment in which the mobile device is estimated to be. The mobile device weights the extent of uncertainty for each satellite's global positioning data based on the predicted probability of obstruction for that satellite. Using these weighted uncertainties, the mobile device selects the extents to which it relies on each satellite's global positioning data when estimating the mobile device's current global position.