Aspects of the present disclosure relate generally to indoor localization, for example, where GPS or other localization signals are unavailable. More specifically, aspects relate to using a particle filter in conjunction with one or more orientation devices to identify a location of a client device with respect to a map of an indoor space. This location may then be used to identify the path of the client device through the indoor space. The paths of a plurality of different client devices through the same indoor space may be used to update the map based on common patterns or inconsistencies between the map and the paths of the plurality of client devices.