Distributed Rendering and Collaborative User Navigation- and Scene Manipulation
Christian Kehl
University of Amsterdam
and UniResearch AS CIPR Bergen
Introduction: Virtual Environments for Decision Making
• Goal: help decision-making process with (3D) Visualizations and advanced interaction capabilities
• Challenges emerge from user feedback
• Generally: – Interactive discussion environment
– Medium size of participants (3 – 50) (+moderator)
– Heterogeneous output devices and interaction demands
3Di discussion with 7 participants (1 moderator), using multi-touch screen
Introduction: Virtual Environments for Decision Making
• Collaborating discipline: Flood Protection Planning
• Starting point: Immersive, single-user VR framework [DeHaan 2009]
VRmeer framework, in short
Introduction: Virtual Environments for Decision Making
• Challenges from Feedback: – Support rendering on flexible, large-scale rendering projection systems
– Integrative navigation for several, possibly remote users (video conference-like situations)
– On-spot, interactive manipulation (annotation) of massive datasets
Large-Scale Projection System (4.5m x 2.5m)
Multi-Modal, Multi-User Navigation
Interactive Annotation
General Approach
• Extension of [DeHaan 2009] to a network-based VE-framework [in this paper] – Remote, Distributed Rendering
– Remote, adaptive, collaborative Navigation
– Remote, collaborative Editing (Manipulation
• Further research: – Remote, Interactive Simulation and Processing
– Adaptive Rendering for arbitrary-sized output devices (e.g. mobile phones)
Idea of Distributed Graphics
Projection-aware Distributed Rendering
• Target output devices: – individual projectors (theatric setup)
– screen walls
– PowerWall
– mainly stereo-projection
• Server-Client configuration
• Synchronized Rendering via timestamp or frame number
• Adaptive projection for planar- and
spherical output environments
Designed, projection-aware network architecture
Collaborative User Navigation
• Particular challenge: unify device capabilities (similar to [Taylor2001])
• Framework of Function- and Device Abstraction
• Navigation synchronization on (dis-) appearance of clients
• Difference-coded view matrices, interpreted on rendering master
Collaborative Scene Manipulation
• Challenge: Modify Out-of-Core loaded datasets in real-time
• Server with high-resolution, Out-of-Core dataset
• Client draws simplified geometry
• Simplification method according to data structure (surface-/volume mesh, point set)
Render Server Render Client
Collaborative Scene Manipulation
• Modification idea based on [Kehl2013]
• Extension to 3D modification primitives
• Per – Vertex inclusion test via implicit function
Collaborative Scene Manipulation
Sample Rendering
Inclusion test via implicit function Box: −𝑎 < 𝑃′
𝑥 < 𝑎
−𝑏 < 𝑃′𝑦 < 𝑏
−𝑑 < 𝑃′𝑧 < 𝑑
Inclusion test idea via implicit function for prism
Technical Results
• Distributed Rendering: – Synchronization by timestamp: larger distortions, high framerates
– Synchronization by frame number: reduced distortions, low framerates
• Collaborative Navigation: – Framework implemented for various joysticks, spacemouse and keyboard
• Collaborative Modification: – Sphere- and OOBB-marker modification interactive
– Prism-based modification to complex for real-time execution (currently)
Distributed Rendering result for independent steering of a 3-screen setup; here: non-stereo
Technical Results
Impact on Decision-Making
• Distributed Rendering allows various rendering setups, actively in use in 4 projects
• Collaborative Navigation gains positive feedback; prime advantage: OS-interoperability
• Coll. Navigation and Modification allows interactive communication in meetings and workshops for Flood Protection Planning
• Techniques also applicable outside flood domain (e.g. seismic exploration, pre-operative planning)
Future Work
• Touch-based interaction poses challenges for distributed Rendering
• Issue with Modification: Simplification needed – > Out-of-Core loading for clients advisable
• Improve OOBB- and Prism-based an notations
• Markers in spatial hierarchies, as [Kehl2013]
• Remote, Interactive Simulation and Processing
• Adaptive Rendering for arbitrary-sized output devices (e.g. mobile phones)
Acknowledgements
References:
[DeHaan2009] G. de Haan, Techniques and Architectures for 3D Interaction, 2009: Delft University of Technology, Delft.
[Kehl2013] C. Kehl, T. Tutenel and E. Eisemann, “Smooth, Interactive Rendering Techniques on Large- Scale, Geospatial Data in Flood Visualisation,” in Information and Communication Technologie (ICT) Open, Eindhoven, The Netherlands, 2013.
[Taylor2001] R. M. Taylor II, T. C. Hudson, A. Seeger, H. Weber, J. Juliano and A. T. Helser, “VRPN: A Device-independent, Network-transparent VR Peripheral System,” in Proceedings of the ACM Symposium on Virtual Reality Software and Technology, New York, NY, USA, 2001.
• CGV group (TU Delft): equipment support, particularly for Dist. Rendering
• Donald Smits Institute (Groningen): collaboration on Dist. Rendering
• dr. ir. Gerwin de Haan: explanation on initial implementation
• Prof. Dr. rer. nat. Herbert Litschke and Dr. Simon J. Buckley: short-term review
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