1. Computer Animation 99Geneva, 26.5.-28.5.99 Universities of Vienna, Bath, Glasgow EPFL (Lausane), iMAGIS (Grenoble), MIRAlab F. Faure, C. Faisstnauer, G. Hesina A. Aubel, M. Escher, F. Labrosse, J.-C. Nebel, J.-D. Gascuel Collaborative animation over the network

2. Computer Animation 99Geneva, 26.5.-28.5.99 Designing animation concurrently Designing animation incrementally –Skeleton / facial / cloth simulation Variety of tools, highly specialized software Combine knowledge of experts Distributed VE / concurrent applications communicate over network –DIVE, NPSNET, SIMNET, VLNET, AVIARY, DVS Collaborative Animation

3. Computer Animation 99Geneva, 26.5.-28.5.99 GOAL Link existing applications into common animation platform  collaborative animation Different, inhomogeneous hardware/software Incompatible data structures No dedicated applications, plug-ins, libraries No porting to different platforms, recompilation Concurrent access to scene database

4. Computer Animation 99Geneva, 26.5.-28.5.99 System structure 1/2 Using network - remote applications communicate employing given protocol Based on client-server architecture Common interchange format: “PaVRML” –VRML97-based language (subset) –Commands to create and modify objects Platform independent Code privacy

5. Computer Animation 99Geneva, 26.5.-28.5.99 System structure 2/2 Server –Minimize network traffic –Relieve clients from communication issues –Manages global database Clients (applications) –Replicate database using own data structures –Scene stored and rendered locally –Internal data representation  PaVRML

6. Computer Animation 99Geneva, 26.5.-28.5.99 Communication Protocol Interface module: send / receive messages –Network connection –Parser: PaVRML  internal data Client login: download scene Update messages –Add, delete, modify objects –Flow control: transmission on demand Notion of time: Online / Offline - animation

7. Computer Animation 99Geneva, 26.5.-28.5.99 System architecture

8. Computer Animation 99Geneva, 26.5.-28.5.99 Online server 1/2 Animation specified while running - no history Change of scene database and scene viewing happen at same time (“real-time”) Server manages global time Updates from clients processed immediately Updates distributed on demand –Increases inconsistency database scene/client –Flow control, discard redundant messages

9. Computer Animation 99Geneva, 26.5.-28.5.99 Online server 2/2

10. Computer Animation 99Geneva, 26.5.-28.5.99 Offline server 1/2 Collaborative construction of animation Change of scene database / scene viewing specified independently (different times) No “actual time”- time specified by clients Client updates processed at specified time Clients query scene state at specific time Complete history stored by server Inherent inconsistency

11. Computer Animation 99Geneva, 26.5.-28.5.99 Offline server 2/2

12. Computer Animation 99Geneva, 26.5.-28.5.99 Examples 1/2 (Video) “Offline” interface Adding objects (“Offline”) –Adding mace to moving character Modifying objects (“Offline”) –Physical simulation of feather joint The snake in the potential (“Online”) –Find region borders (based on image gradient)

13. Computer Animation 99Geneva, 26.5.-28.5.99 Examples 2/2 (Video) The common studio (“Online”) –Image segmentation (Bath) –Objects created by photogrammetry (Glasgow) –Facial animation (Geneva) –Keyframe animated bodies (Glasgow) –Body reconstruction (EPFL)

14. Computer Animation 99Geneva, 26.5.-28.5.99 Conclusions VRML-based distributed environment Contribute to common animation Integrating existing (previously incompatible) tools and applications into common scene Build on preexisting animations Requires only addition communication layer Incrementally design complex animations Code privacy

15. Computer Animation 99Geneva, 26.5.-28.5.99 Future work Permission restrictions Enhance smart streaming –Exploit server knowledge about scene/clients (e.g. camera position) –Levels of Detail –Priority management Introduce physical data (mass, force) Increase compatibility with existing standards