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© 2002 Lehrgebiet Rechnernetze und Verteilte Systeme
Architecture of a shared-image electronic whiteboard in telemedicine
Projekt INTER-FACE
Michael Fromme
Lehrgebiet Rechnernetze und Verteilte Systeme
Universität Hannover
Michael Fromme© 2002 Lehrgebiet Rechnernetze und Verteilte Systeme Slide 2
Outline
• Conferencing scenarios in INTER-FACE• Network infrastructure in INTER-FACE• Whiteboard software and images• Architecture for whiteboard communication• System architecture and implementation• Conclusion
Michael Fromme© 2002 Lehrgebiet Rechnernetze und Verteilte Systeme Slide 3
Project INTER-FACE
• Topic– maxillofacial surgeries with bone rearrangements
– computer-aided planning of the surgery
– pre-operative treatment by orthodontists
– multiple consultations of surgeon and orthodontist necessary
• Aim– allow some consultations with the aid of a video conference
– build a working environment for that case
– evaluate working environment with respect to• efficiency• practical requirements• patient experience
Michael Fromme© 2002 Lehrgebiet Rechnernetze und Verteilte Systeme Slide 4
Computer aided surgery planning
pre-surgerycomputer-aided
surgery planningpost-surgery
Michael Fromme© 2002 Lehrgebiet Rechnernetze und Verteilte Systeme Slide 5
Technical Equipment
Orthodontist equipment• Video communication terminal (H.323)• PC with whiteboard• intra-oral camera
Michael Fromme© 2002 Lehrgebiet Rechnernetze und Verteilte Systeme Slide 6
Communication structure
H.323 MCU
(Hanover)
IWB Server
(Hanover)
Orthodontist
(Munich)
One or more specialists
at university hospitals
(Munich, Düsseldorf, or Stuttgart)
point-to-point or
multipoint conference
Michael Fromme© 2002 Lehrgebiet Rechnernetze und Verteilte Systeme Slide 7
Network infrastructure
Düsseldorf
Stuttgart
Munich
Orthodontists
(Munich)
Hanover
St. Augustin
H o
s p
i t
a l
s
SDSL
1Mbps
GWiN
620 Mbps
decix / DFN
Michael Fromme© 2002 Lehrgebiet Rechnernetze und Verteilte Systeme Slide 8
Image Whiteboard functionality
• Load and display common image formats
(TIFF, JPEG, BMP, FlashPix, PNG, PNM, GIF)
• Image annotations• Image manipulations
(zoom, pane, color effects)
• Distribute and synchronize image and annotations
• Use color management functionality
• Session management• Print and save images
Michael Fromme© 2002 Lehrgebiet Rechnernetze und Verteilte Systeme Slide 9
Every device processes color in a different way
ICC Color Management
We need additional processing for a true reproduction of color.
This processing is done by a color management system.
printer
computer
scanner
digital Kamera
screen
Michael Fromme© 2002 Lehrgebiet Rechnernetze und Verteilte Systeme Slide 10
Color Management
printer
computer
scanner
digital Kamera
screen
device dependend
color space
device dependend
color space
device independend
color space
input profile
output profile
screen profile
Michael Fromme© 2002 Lehrgebiet Rechnernetze und Verteilte Systeme Slide 11
Color Management in IWB
• Features– uses color management facility of Java Advanced Imaging API– images can be loaded together with explicit input profile– images are distributed and processed in the device independent color space
SRGB
• Notes– need of accurate profiles for input / output devices, they can be generated
with a spectral photometer and calibration software– many manufacturer provide profiles for their devices
Michael Fromme© 2002 Lehrgebiet Rechnernetze und Verteilte Systeme Slide 12
IWB Network Communication
• Multi-point conferences with IWB– IP multicast capable, but
works in IP multicast networks
only
– TCP and central server needed for SDSL connected partners or partners behind firewalls
• Multi-point protocol features– session handling
– reliable transmission
– startup syncronization (image bootstrap) with unicast
Michael Fromme© 2002 Lehrgebiet Rechnernetze und Verteilte Systeme Slide 13
System architecture
JAI 1.1
LRMP
TCP UDP
User-InterfaceImage-Handling Group Control
Data Distribution Layer
Operating System
Remote Object InvocationJava 2D
Java JVM 1.3.1
Michael Fromme© 2002 Lehrgebiet Rechnernetze und Verteilte Systeme Slide 14
Remote Object Invocation
Object method call
Object serialization
transport connection
Request/Reply
Object method call
Object de-serialization
Michael Fromme© 2002 Lehrgebiet Rechnernetze und Verteilte Systeme Slide 15
ROI Transport Protocols
• Unicast– TCP connection for reliable transport– UDP connections (variants: reliable, rate-limited)
• Multicast– UDP (unreliable)– Lightweight Reliable Multicast Protocol LRMP (Inria)– Reliable Multicast Framework RMP (TASC)
• Multicast simulation– transport connection is TCP from peer to server– central router component simulates unicast / multicast transmission
• ROI Object Method Invocation Semantics– normal call (Unicast only)– one-way call– reliable group call with one return value (first value selected)– group call with return value array
Michael Fromme© 2002 Lehrgebiet Rechnernetze und Verteilte Systeme Slide 16
Session Initiation Example
Iw bC onta inerIw bServer
Iw bC onnection
w elcom e(call)
getG roupM em berList().addM em ber(ID 0,ID 1)
create()
getU pdate(unicastC lientStub)
* [a ll shared im ages] setIm ageD ata(SharedIm age)
* [a ll shared annotations] setAnnotation(SharedAnnotation)
* [a ll docum ents] updateR eady(D ocum ent)
jo inG roup(getLocalM em ber())
Michael Fromme© 2002 Lehrgebiet Rechnernetze und Verteilte Systeme Slide 17
Conclusion
• Multi-user whiteboard– uses group-oriented middleware
– based on Java Image API
• Related information– http://www.rvs.uni-hannover.de/projects/interface { german }
– http://www.rvs.uni-hannover.de/products/iwb
• Further work– better adoption to the medical environment
– integration for medical software (surgery planning)
– user interface, input formats and functionality
– security, e.g. encryption of network communication
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