Enabling collaboration in virtual reality navigators

In this paper we characterize a feature superset for Collaborative Virtual Reality Environments (CVRE), and derive a component framework to transform stand-alone VR navigators into full-fledged multithreaded collaborative environments. The contributions of our approach rely on a cost-effective and extensible technique for loading software components into separate POSIX threads for rendering, user interaction and network communications, and adding a top layer for managing session collaboration. The framework recasts a VR navigator under a distributed peer-to-peer topology for scene and object sharing, using callback hooks for broadcasting remote events and multicamera perspective sharing with avatar interaction. We validate the framework by applying it to our own ALICE VR Navigator. Experimental results show that our approach has good performance in the collaborative inspection of complex models.Postprint (published version

On extending collaboration in virtual reality environments

We characterize the feature superset of Collaborative Virtual Reality Environments (CVREs) out of existing implementations, and derive a novel component framework for transforming standalone VR tools into full-fledged multithreaded collaborative environments. The contributions of our approach rely on cost-effective techniques for loading graphics rendering, user interaction and network communications software components into separate threads, with a top thread for session collaboration. The framework recasts VR tools under a scalable peer-to-peer topology for scene sharing, callback hooks for event broadcasting and multicamera perspectives of avatar interaction. We validate the framework by applying it to our own Alice VR navigator. Experimental results show good performance of our approach in the collaborative inspection of complex models.Postprint (published version

and XML Metadata for Web Based Instruction

Most current solutions for Web Based Instruction (WBI) use a centralized management model and a proprietary internal representation. The AVANTE Architecture is a WBI environment assembled using CORBA distributed components, implementing core services such as course management, user authentication, collaborative work, database access, presentation, and others. The AVANTE components conform to a 4-tiered model, with Client, Presentation, Management, and Low-Level Services component sublayers. Emergent XML standards for WBI describe all metadata definitions. Components at the Management layer manipulate JDBC-SQL data from the Low-Level Services Layer, and combine it with corresponding XML Schemas, instantiating course objects as new XML descriptions and component services. A filter-mapping service in the Presentation layer produces the dynamic HTML web pages needed for user interaction, processing these XML descriptions by applying one or more previously defined XSL stylesheets. A similar mechanism implements interface customization and remote service administration. The developed WBI system was deployed with open source software. Adding CORBA components easily achieves on-demand scalability. Future services include auditing, adaptive interfaces, grading, content development, and integration with existing systems

AVANTE: An architecture of CORBA components and XML Metadata for Web Based Instruction

Most current solutions for Web Based Instruction (WBI) use a centralized management model and a proprietary internal representation. The AVANTE Architecture is a WBI environment assembled using CORBA distributed components, implementing core services such as course management, user authentication, collaborative work, database access, presentation, and others. The AVANTE components conform to a 4-tiered model, with Client, Presentation, Management, and Low-Level Services component sublayers. Emergent XML standards for WBI describe all metadata definitions. Components at the Management layer manipulate JDBC-SQL data from the Low- Level Services Layer, and combine it with corresponding XML Schemas, instantiating course objects as new XML descriptions and component services. A filter-mapping service in the Presentation layer produces the dynamic HTML web pages needed for user interaction, processing these XML descriptions by applying one or more previously defined XSL stylesheets. A similar mechanism implements interface customization and remote service administration. The developed WBI system was deployed with open source software. Adding CORBA components easily achieves on-demand scalability. Future services include auditing, adaptive interfaces, grading, content development, and integration with existing systems

A hybrid rugosity mesostructure (HRM) for rendering fine haptic detail

The haptic rendering of surface mesostructure (fine relief features) in dense triangle meshes requires special structures, equipment, and high sampling rates for detailed perception of rugged models. Some approaches simulate haptic texture at a lower processing cost, but at the expense of fidelity of perception. We propose a better method for rendering fine surface detail by using image-based Hybrid Rugosity Mesostructures (HRMs), composed of paired maps of piece-wise heightfield displacements and corresponding normals, which are layered on top of a less complex mesh, adding greater surface detail than the one actually present in the geometry. The core of the algorithm renders surface features by modulating the haptic probe's force response using a blended HRM coat. The proposed method solves typical problems arising at edge crossings, concave foldings and smoothing texture stitching transitions across edges. By establishing a common set of specially devised meshes, HRM mesostructures, and a battery of performance tests, we build a usability testing framework that allows a fair and balanced experimental procedure for comparing haptic rendering approaches. The trial results and user testing evaluations show the goodness of the proposed HRM technique in the accurate rendering of high 3D surface detail at low processing costs, deriving useful modeling and perception thresholds for this technique