Modelling and Handling Seams in Wide-Area Sensor Networks Joseph Newman 12 Gerhard Schall 2 Dieter Schmalstieg 2 1 Computer Laboratory University of Cambridge 2 Insitute for Computer Graphics and Vision Technical University of Graz Thursday Oct 12th, 2006 Newman, Schall, Schmalstieg Universities of Cambridge and Graz Modelling and Handling Seams in Wide-Area Sensor Networks
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Modelling and Handling Seams in Wide-AreaSensor Networks
Joseph Newman12 Gerhard Schall2 Dieter Schmalstieg2
1Computer LaboratoryUniversity of Cambridge
2Insitute for Computer Graphics and VisionTechnical University of Graz
Thursday Oct 12th, 2006
Newman, Schall, Schmalstieg Universities of Cambridge and Graz
Modelling and Handling Seams in Wide-Area Sensor Networks
Introduction
Disciplines of Wearable Computing, Augmented Reality andUbiquitous Computing highly inter-related
Barriers to cross-fertilisation and collaboration
cultural, financial and technical
Technological choices introduce assumptions later reflected indesign patterns
Propose design patterns that match technical constraints, notconstrained by semi-arbitrary technological choices.
We are going to buy tracker X and display Y in order to do ZCould we do A, B, . . . ?Could we cooperate/interoperate with F, G, . . . ?
Newman, Schall, Schmalstieg Universities of Cambridge and Graz
Modelling and Handling Seams in Wide-Area Sensor Networks
Comparison of Sensor Characteristics
VR AR UbicompUpdate rate 15 — 500 Hz ∼1 Hz
Latency < 30 ms ∼1 s
Cost Expensive Cheap
Working volume Small (< 5m3) Large
Granularity Fine Coarse
Quantity Scarce Abundant
Newman, Schall, Schmalstieg Universities of Cambridge and Graz
Modelling and Handling Seams in Wide-Area Sensor Networks
Tracking versus Location
VR AR UbicompTracking X X 7
Location 7 X X
Newman, Schall, Schmalstieg Universities of Cambridge and Graz
Modelling and Handling Seams in Wide-Area Sensor Networks
Event Bandwidth
Event Description BandwidthTracker Pose At timestamp T, locatable A has
pose P measured by tracker B.High15 – 50 Hz
Tracker Scope Locatable A is either being tracked by tracker B, or is no longer tracked by tracker B
Medium1 – 0.1 Hz
Data Flow Reconfiguration
The flow of data from trackers to clients is reconfigured.
Low0.2 – 0.01 Hz
Measurement Measurement of an environmen-tal property, e.g. points C and D,are separated by distance d.
Very low < 0.01 Hz
Newman, Schall, Schmalstieg Universities of Cambridge and Graz
Modelling and Handling Seams in Wide-Area Sensor Networks
Design Patterns
AR/VR applications run as sessions
few participants and tracked implements usually defined a priorilow latency & high throughput
Ubicomp applications run as services 24/7 focussing onscalability and stability
Network protocols: various TCP/IP or multicast, e.g. VRPN
Federated data model: Nexus, QoSDream, SPIRIT, otherproprietary middlwares
Dwarf expresses needs and abilities of clients and services aspredicates, which are then matched in a distributed fashion
Pipes-and-filter: OpenTracker — sources, sinks and filters
Newman, Schall, Schmalstieg Universities of Cambridge and Graz
Modelling and Handling Seams in Wide-Area Sensor Networks
Ubitquitous Tracking Architecture
sensor S1
UbitrackServerSpatialRelationshipGraph Server
ClientTier Client #1
Query/Response(OT configuration)
sensor S0
Client #n
sensor SN
Query/Response(spatial search)
Query/Response(OT configuration)
Newman, Schall, Schmalstieg Universities of Cambridge and Graz
Modelling and Handling Seams in Wide-Area Sensor Networks