1. A system configured for providing a single polygonal navigation mesh in a virtual space by which objects of varying size can traverse, the system comprising: one or more processors configured to execute computer program modules, the computer program modules comprising: a navigation mesh module configured to provide a navigation mesh associated with the virtual space, the navigation mesh formed from polygonal tiles, adjacent ones of the polygonal tiles being joined along adjacent polygonal tile edges, outer boundaries of the navigation mesh confining paths by which the objects can traverse a surface or volumetric region in the virtual space such that the objects cannot breach an outer boundary of the navigation mesh, individual ones of the objects having an object size associated therewith; a constraint initialization module configured to determine constraints associated with the navigation mesh based on a given object size, the constraints being within the outer boundaries of the navigation mesh and configured to confine a position of a center of a given object having the given object size to prevent the given object from breaching the outer boundary of the navigation mesh; and a mesh traversal module configured to determine whether the given object can traverse from a first polygonal tile of the navigation mesh to a second polygonal tile of the navigation mesh based on the constraints.