Mobile networked virtual environments (mNVE's) are a new, emerging type of virtual environments. Mobile 3D maps that support dynamic entities and communication between clients are a subcategory of mNVE's, intended for navigation and location-based information browsing. Models and entities portrayed in 3D maps represent real environments and entities, such as buildings, vehicles and people. Our main contribution is in developing a lightweight and scalable scheme for real dynamic entity management and visibility culling by exploiting geometry of urban environments, the honesty of locally positioned clients and the lack of interference between clients. We bind moving entities to a topological network consisting of street segments, crossings and larger areas, all associated to precalculated visibility cells. Our system reduces visibility determination to a simple
cell occupation logic, performed at smart clients or proxies. In this scheme, servers act as fast message passing switches, managing client subscription and query tables, simply forwarding state update messages. Computational scalability is ensured by transferring computations to client side, and networking scalability by spatially localized servers, which allow roaming by subscribing to each others neighboring visibility cells.