Multiple mode learning of absolute altitude of floors of a building

The absolute altitude of multiple floors of a building are determined using a multi-mode learning process. Processor(s) execute application program code to cause an apparatus to operate in an initial floor learning mode that includes capturing outdoor altitude estimates for the apparatus and determining, based in part on the outdoor altitude estimates, instant altitude estimates for an initial floor of the building. An absolute altitude estimate for the initial floor is determined based one the instant altitude estimates. After the absolute altitude estimate for the initial floor satisfies a first threshold certainty, the apparatus operates in a subsequent floor learning mode configured for determining respective absolute altitudes for floors of the building based on the absolute altitude estimate for the initial floor and a priori floor height information for the building, a sensor-based altitude change estimate, and/or a determined floor height for the building.