Article

A Simplification Architecture for Exploring Navigation Tradeoffs in Mobile VR

01/2004; DOI: 10.1109/VR.2004.6
Source: CiteSeer

ABSTRACT Interactive applications on mobile devices often reduce data fidelity to adapt to resource constraints and variable user preferences. In virtual reality applications, the problem of reducing scene graph fidelity can be stated as a combinatorial optimization problem, where a part of the scene graph with maximum fidelity is chosen such that the resources it requires are below a given threshold and the hierarchical relationships are maintained. The problem can be formulated as a variation of the Tree Knapsack Problem, which is known to be NP-hard. For this reason, solutions to this problem result in a tradeoff that affects user navigation. On one hand, exact solutions provide the highest fidelity but may take long time to compute. On the other hand, greedy solutions are fast but lack high fidelity. We present a simplification architecture that allows the exploration of such navigation tradeoffs. This is achieved by a formulating the problem in a generic way and developing software components that allow the dynamic selection of algorithms and constraints. The experimental results show that the architecture is flexible and supports dynamic reconfiguration.

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    ABSTRACT: Heterogeneity in mobile computing devices and application scenarios complicates the development of collaborative software systems. Heterogeneity includes disparate computing and communication capabilities, differences in users needs and interests, and semantic conflicts across different domains and representations. In this paper, we describe a software framework that supports mobile collaboration by managing several aspects of heterogeneity. Adopting graph as a common data structure for the application state representation enables us to develop a generic solution for handling the heterogeneities. The effect external forces, such as resource constraints and diverging user interests, can be quantified and controlled as relational and attribute heterogeneity of state graphs. When mapping the distributed replicas of the application state, the external forces inflict a loss of graph information, resulting in many-to-one correspondences of graph elements. A key requirement for meaningful collaboration is maintaining a consistent shared state across the collaborating sites. Our framework makes the best of maximizing the state consistency, while accommodating the external force constraints, primarily the efficient use of scarce system resources. Furthermore, we describe the mobility aspects of our framework, mainly its extension to peer-to-peer scenarios and situations of intermittent connectivity. We describe an implementation of our framework applied to the interoperation of shared graphics editors across multiple platforms, where users are able to share 2D and 3D virtual environments represented as XML documents. We also present performance results, namely resource efficiency and latency, which demonstrate its feasibility for mobile scenarios.
    Computer Supported Cooperative Work 12/2004; 13(5):603-638. · 0.61 Impact Factor

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May 22, 2014