Technical Overview

1. Technical Overview Erik Brisson ebrisson@bu.edu

2. What's in a virtual world? BPC: Art and Computation – Summer 2008

3. What's in a virtual world? • An environment • Representations of physical objects • Visual models • Auditory elements • Interactions with objects • Representations of people - avatars • Communication • Gesturing • Telephony • Video BPC: Art and Computation – Summer 2008

4. Student work in VR context • Produce images (texture maps) • Produce objects (3D models) • Produce sounds (audio files) • Produce movement (sequences) • Produce behavior (logo programs) • Arrange in space (config scripts) BPC: Art and Computation – Summer 2008

5. Software used • Corel Painter: Image processing and painting, 2D animation • Audio: Audacity • Modeling: Maya • Programming: Logo • VR: BU’s DAFFIE BPC: Art and Computation – Summer 2008

6. Images into VE +  BPC: Art and Computation – Summer 2008

7. 2D Animation into VE  BPC: Art and Computation – Summer 2008

8. Defining geometry hquad, 2, 2, 4, 2, 4, 4, 2, 4, 0 vrect, 2, 5, 4, 5, 2 vrect, 4, 5, 4, 7, 2 vrect, 4, 7, 2, 7, 2 vrect, 2, 7, 2, 5, 2 vcyl, 0, 2, 0.5, 3 vcone, 2, -5, 1, 2 vrect, -1.5, -3, 0, -3, 2 vrect, 0, -3, 2, -1, 2 vrect, 2, -1, 0.5, -1, 2 vrect, 0.5, -1, -1.5, -3, 2 hquad, 2, -5, 4, -3, 2, -1, 0, -3, 2 BPC: Art and Computation – Summer 2008

9. Animation of 3D models • Model sequence • What is changing? • Shape • Elements • movement • Rotation • Scale • Whole object • Movement • Rotations • Scale BPC: Art and Computation – Summer 2008

10. Sound mapping + BPC: Art and Computation – Summer 2008

11. Programming in VE: Logo BPC: Art and Computation – Summer 2008

12. 3D Models and motion: Maya BPC: Art and Computation – Summer 2008

13. Scene description file BPC: Art and Computation – Summer 2008

14. DAFFIE Distributed Interactive Visually and aurally rich Input (models, images and sounds) from variety of available tools Simple import method Script driven Accessible to non-expert users Extensible by programmers BPC: Art and Computation – Summer 2008

15. The DAFFIE scene graph The world-room-group-sequence hierarchy BPC: Art and Computation – Summer 2008

16. arp script example: basic sequence arp 2.0 name clusterseq geom_path ./ playspeed 10 frame geom_show clustergeom0000.obj frame geom_show clustergeom0001.obj frame geom_show clustergeom0002.obj frame geom_show clustergeom0003.obj end BPC: Art and Computation – Summer 2008

17. Example - adding sound frame geom_show clustergeom0000.obj sound_xyz_stereo 180.932040 -157.771123 -103.679324 180.932040 -43.291371 -103.679324 sound_move h2o4.aif sound_trigger h2o4.aif frame geom_show clustergeom0001.obj sound_xyz_stereo 187.016266 -157.446847 -103.679324 174.847813 -43.615647 -103.679324 sound_move h2o4.aif frame geom_show clustergeom0002.obj sound_xyz_stereo 193.031556 -156.477695 -103.679324 168.832524 -44.584799 -103.679324 sound_move h2o4.aif BPC: Art and Computation – Summer 2008

18. arp script example: move object frame geom_show pot21.iv geom_xyz 5.0 2.1 9.3 geom_hpr 0.0 90.0 0.0 geom_show drop21.obj frame geom_show pot22.iv geom_xyz 5.5 1.9 3.2 geom_hpr 0.0 91.0 0.0 geom_show drop22.obj BPC: Art and Computation – Summer 2008

19. arp script: arpgroup file arpg 2.0 name gbdog geom_size 1.0 geom_path ./ geom_hpr 0 90 0 geom_xyz 0.0 0.1 0.0 geom_rep dog0.obj trigger_method cycle seq_path ./ seq_hpr 0 90 0 seq_xyz 0.0 0.1 0.0 seq_file gbdog.seq end BPC: Art and Computation – Summer 2007

20. arp scripts: arproom file arproom 2.0 name cart-models enter_xyz 3.0 4.0 4.0 enter_hpr 30.0 -98.0 0.0 group_xyz 0 0 0 group_hpr 0 0 0 group_path ../models/purple_cube/ group purple_cube.arpg group_xyz 2 -4 0 group_hpr 60 0 0 group_path ../models/blue_cube/ group blue_cube.arpg group_xyz -3 -5 2 group_hpr 0 0 0 group_path ../models/orange_sphere/ group orange_sphere.arpg end BPC: Art and Computation – Summer 2008

21. The DAFFIE event system • Communication between agents BPC: Art and Computation – Summer 2008

22. 3D Coordinate system BPC: Art and Computation – Summer 2007

23. Navigation - user experience • 6 degrees of freedom • Map onto various input devices • Communication with viewer (old model) - direct sending of xyz,hpr wand motion to viewer • New model – agent sending of transform matrices to viewer BPC: Art and Computation – Summer 2008

24. Triggering objects • Light stick (by viewer) • Proximity (by viewer) • Proximity (by agent) • Other (by agent) • The trigger event BPC: Art and Computation – Summer 2008

25. World state and events • Object descriptions • Trigger • Transforms • Switches • Navigation • Sound • Video • Etc. BPC: Art and Computation – Summer 2008

26. Agents and events • Using events to control elements of the world • Triggering sequences • Moving objects • Changing rooms • Navigation BPC: Art and Computation – Summer 2008

27. Telephony • Telephony collector agent • Gets audio stream from microphone • Chops into sound samples • Sends sequence of sound samples • Sound server • Receives sequence of sound samples • Reassembles audio stream from sound samples • Sends reconstructed audio stream to speakers BPC: Art and Computation – Summer 2008

28. Video texture maps • Video as sequence of images • Video generator • Sends sequence of images • Viewer • Receives sequence of images • Uses texture mapping on an object in scene BPC: Art and Computation – Summer 2008

29. Stereo displays • Physical issues and camera issues • Using polarizing filters • Setting up the view • What looks closer vs further • Relative position to the screen and viewer BPC: Art and Computation – Summer 2008

30. Tiled walls • Issues and differences • Head node vs render nodes • Event management / avatars / triggering • Virtual cameras • Alignment BPC: Art and Computation – Summer 2008

31. The End BPC: Art and Computation – Summer 2008