With the proliferation of location-aware mobile devices, crowd tracking and services based thereon are starting to emerge. For example, an exemplary system for forming and tracking crowds of users is described in U.S. patent application Ser. No. 12/645,532 entitled FORMING CROWDS AND PROVIDING ACCESS TO CROWD DATA IN A MOBILE ENVIRONMENT, U.S. patent application Ser. No. 12/645,539 entitled ANONYMOUS CROWD TRACKING, U.S. patent application Ser. No. 12/645,535 entitled MAINTAINING A HISTORICAL RECORD OF ANONYMIZED USER PROFILE DATA BY LOCATION FOR USERS IN A MOBILE ENVIRONMENT, U.S. patent application Ser. No. 12/645,546 entitled CROWD FORMATION FOR MOBILE DEVICE USERS, U.S. patent application Ser. No. 12/645,556 entitled SERVING A REQUEST FOR DATA FROM A HISTORICAL RECORD OF ANONYMIZED USER PROFILE DATA IN A MOBILE ENVIRONMENT, U.S. patent application Ser. No. 12/645,560 entitled HANDLING CROWD REQUESTS FOR LARGE GEOGRAPHIC AREAS, and U.S. patent application Ser. No. 12/645,544 entitled MODIFYING A USER'S CONTRIBUTION TO AN AGGREGATE PROFILE BASED ON TIME BETWEEN LOCATION UPDATES AND EXTERNAL EVENTS, all of which were filed Dec. 23, 2009 and are hereby incorporated herein by reference in their entireties.
One issue with existing crowd formation techniques is that they do not account for tangible physical boundaries, such as walls, that may physically prevent spatially proximate users from being in the same crowd. Similarly, existing crowd formation techniques do not account for intangible physical boundaries, such as boundaries between departments in a department store, that may logically prevent spatially proximate users from being in the same crowd. As such, there is a need for a system and method for forming crowds of users in a manner that takes into account known physical boundaries.