Abstract: To calibrate a device, a system receives an indication of current weather conditions at a geographic area, obtains, from a database, elevation data for the geographic area, and generating expected measurements of atmospheric pressure at the geographic area using the indication of weather conditions and the elevation data for the geographic area. The system then causes at least one mobile device located in the geographic area and equipped with a barometer to calibrate the barometer using the expected measurements of atmospheric pressure.

Abstract: Positioning mobile devices in a three-dimensional space includes receiving multiple traces, each trace corresponding to a sequence of atmospheric pressure readings from a respective mobile device, receiving indications of signals received by the mobile devices from signal sources concurrently with the atmospheric pressure readings, generate similarity metrics for the multiple traces using the indications of other signals received by the mobile devices, the similarity metrics being indicative of associations between the signal sources and the atmospheric pressure readings, and determine estimated changes in elevation over time for the multiple traces using the generated similarity metrics.

Abstract: Positioning mobile devices in a three-dimensional space includes receiving multiple traces, each trace corresponding to a sequence of atmospheric pressure readings from a respective mobile device, receiving indications of signals received by the mobile devices from signal sources concurrently with the atmospheric pressure readings, generate similarity metrics for the multiple traces using the indications of other signals received by the mobile devices, the similarity metrics being indicative of associations between the signal sources and the atmospheric pressure readings, and determine estimated changes in elevation over time for the multiple traces using the generated similarity metrics.