Conceptual framework of a generalized roaming scheme

Roaming is an important system task of softcopy workstations. The implementation of roaming in most of today's softcopy workstations is an emulation of the same operation in analytical plotters. The performance is quite inferior to that which photogrammetrists are accustomed when moving the measuring mark. Mimicking the analytical plotter imposes self-inflicting constraints on the solution which are technologically and procedurally unjustified. We take a fresh look at roaming and describe in this paper a conceptual framework that is based on extending the spatial extent from one model to the entire project. The information in which roaming is performed is extended from imagery to include vector data, DEMs, databases, and design data. We show that it is feasible to roam within a project of 300 color images without ever explicitly identifying models. Lineal features can be digitized in stereo, across the project. Rapid mouse movements in navigation mode cause the system to display imagery monoscopically at the proper resolution. The third roaming mode resembles the 'drive to' feature of analytical plotters with the distinct difference that any point within the project can be reached.