IEEE VR 2003 Ribbon Networks for Modeling Navigable Paths of Autonomous Agents in Virtual Urban Environments Peter Willemsen Joseph Kearney Hongling Wang School of Computing Dept. Of Computer Science University of Utah University of Iowa IEEE VR 2003 Research Overview Dynamic VE Vehicles, pedestrians, etc Lots of them! Behavior and scenario programming Environment Modeling Adapted to the needs of behavior and scenario programs Environment ScenarioBehavior IEEE VR 2003 Motivation Virtual environments as laboratories for psychological study Child bicycle-riding behavior Dynamic virtual environments need activity Realistic behaviors Replicable scenarios Spatial awareness What routes are accessible? Where are other objects? What constraints are important? IEEE VR 2003 Focus of Talk - Environment Geometric Information Shape and curve of pathways Topological Information Interconnections between pathways Logical information Rules governing behavior Occupancy Information Locations of objects IEEE VR 2003 Related Research Farenc et al - Informed Environments Eurographics 1999 Behavioral content connected to scene graph Donikian and Thomas - VUEMS Eurographics 2000, CGI 1997 Comprehensive system for modeling urban networks of streets, sidewalks, and tramways Road modeling for driving simulation Civil engineering design of roadways Desirable properties for high speed roadways IEEE VR 2003 Ribbon Networks Model urban streets, sidewalks, and navigable ways as ribbons in space Curvilinear coordinate system Arc-length parameterized spline Fast lookup based on distance Defines geometry and orientation of navigable surface Provides frame of reference for local spatial relationships Annotations (e.g. speed zones, passing regions, features) IEEE VR 2003 Ribbon Network Computations Map (X,Y,Z) (D,O,L) Closest Point Computation Typical bottleneck Usual optimization techniques fail Slow convergence and divergence Hybrid Method Combines Newtons method and quadratic minimization fast and robust (D, O, L) IEEE VR 2003 Ribbon Network Attributes Ribbons capable of representing (all?) types of roadways Curvy, straight, engineering specified Cracks due to modeling errors fixed by imperceptible numerical nudges Attributes annotate ribbon structure Lanes (parallel streams channel traffic flow) Speed limit signs, passing zones, and behavior associated objects, such as flag men Ribbon establishes convenient local access to attributes IEEE VR 2003 Intersections Splice together incoming and outgoing lanes Corridors (single lane ribbons) Dependencies Corridor relationships Crossing, merging, crosswalk, right of way, traffic control Zero-length intersections Change road cross-section Hierarchical intersections Pedestrians intersections Type and instance Corridor C 0 (crosses C 1 ) (merges_with C 2 ) (right_of_way C 1,C 2 ) IEEE VR 2003 Paths as Overlay Ribbons Single-lane ribbon overlayed on the road network Simplify behavior at road/intersection junctures Tracking Collision avoidance Dynamically composed by individual behaviors Provide egocentric, local coordinate system for environment queries Insert picture of Washington and Clinton intersection overlaid with a path ribbon. IEEE VR 2003 Occupancy Spatial relationships based on ribbon structure (INSERT PICTURE HERE) Occupancy queries: Two Forms Leader First object on ribbon segment List of leaders Ordered list of objects on ribbon segment IEEE VR 2003 Results Ribbon network forms substrate for the Hank Simulator General purpose virtual environment software Simulator used hundreds of hours in production mode Database queries (almost) never fail Behavior code is greatly simplified Environment Description Format (EDF) Modeling language for road networks IEEE VR 2003 The System in Action (movie) IEEE VR 2003 Conclusions Solid conceptual model of urban landscape Ribbon networks Geometry matches shape and curve of pathways Topology describes interconnections Logical attributes provide constraints and socio-cultural aspects Occupancy sets up inter-object relationships Behaviors obtain spatial awareness Environment model is efficient, robust, and simple Supports behavior and scenario control programs IEEE VR 2003 Future Work Automatic generation of models from GIS Data Terrain from roads Incorporating pedestrian models Integration into physical environment system VTerrain.org IEEE VR 2003 Collaborators University of Iowa, Computer Science Jim Cremer Zhihong Wang Scott Davis Jill Secher University of Iowa, Psychology Jodie Plumert University of Iowa, Math Ken Atkinson IEEE VR 2003 Acknowledgments Visual Database Expertise Joan Severson Shayne Gelo Kate Kearney NSF Support: CDA , INT , EIA , and IIS IEEE VR 2003 Importance of Environment This slide was earlier, but didnt like it there Not sure if I like it in any case Behaviors are difficult to create! Time consuming Part of Environment! Behaviors and enviroment mesh together Provide sets of queries for behavior Where am I? (Spatial awareness) Whos near me? (Occupancy) Where can I go from here? (Geometry, topology) What rules should I obey here? (Logic) IEEE VR 2003 Modeling Language System is built upon a language Describes the ribbon networks Example IEEE VR 2003 Query Environment Database System provides run-time queries Where am I? Where can I go? Other examples Overview the general query structure of the run- time system Abstract behavioral queries