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Mobile Augmented Reality Tssio Knop de Castro Visgraf Lab, IMPA, - PowerPoint PPT Presentation

Mobile Augmented Reality Tssio Knop de Castro Visgraf Lab, IMPA, Rio de Janeiro 2011 Intro Mobile Augmented Reality AR Toolkit Nearest Tube App Enhance the perception of the real world Motivation Trip Advisor How to provide


  1. Mobile Augmented Reality Tássio Knop de Castro Visgraf Lab, IMPA, Rio de Janeiro 2011

  2. Intro – Mobile Augmented Reality AR Toolkit Nearest Tube App ● Enhance the perception of the real world

  3. Motivation Trip Advisor ● How to provide useful information without confusing the user? ● Is it possible to really insert a virtual object onto a real scene in a realistic way?

  4. Goal To explore the possibilities and limitations of Mobile Augmented Reality concerning information insertion and objects rendering

  5. Mobile Development

  6. The device: Nokia N900 ● 600 MHz ARM processor ● 256 MB RAM ● 5MP programmable camera

  7. Maemo Development ● MADDE (Maemo Application Development and Debugging Environment) ● Cross-compiling ● Multi-platform support (Linux (32-bit/64-bit), Windows, Mac OS X) ● Comes with Nokia Qt SDK =) ● It's a technology preview =( ● Scratchbox

  8. Maemo Development ● Main challenges: ● Small community, poor documentation ● How to compile and configure external libraries for the N900 using this Qt-based environment? (however, Qt is a good tool to create interfaces)

  9. AR Toolkit Plus ● Marker-based augmented reality: ● Given a physical marker, this toolkit is able to compute the camera position and orientation in real time ● Hundreds of markers templates ● There are marker-less methods as well (more expensive) ● We just need a good transformation matrix.

  10. AR Toolkit Plus ● Main challenges: ● It's an external library: really tricky on MADDE ● No longer updated since June 2006

  11. Coding in OpengGL ES 2.0 ● OpenGL ES 2.0 ● Programmable Shaders (GLSL) ● No fixed function pipeline

  12. OpenGL ES 2.0

  13. Overview Objects Setup VBO Setup Texture Detect Markers, Capture estimate Render! (GStreamer) transf. matrix (ARToolkitPlus) Compile and link shaders

  14. GStreamer Powerful pipeline-based multimedia framework ●

  15. Experiments ● 2D Text ● Texture Overlay ● 3D Text ● Shadow Mapping 2D Text

  16. Texture Overlay

  17. 3D text ● More immersive than the 2D approach ● Array of vertices ● Simple shader Video: 3D text

  18. Shadow Mapping Lance Williams, Casting curved shadows on curved surfaces. ● SIGGRAPH Comput. Graph. 12, 3 (August 1978) – objects light camera

  19. Shadow Mapping Render objects from Light POV into a buffer ● This buffer shows which regions are illuminated ● objects light camera

  20. Shadow Mapping Render from the Camera POV using the computed depth buffer ● The (x,y,z) coordinates which aren't visible from light POV are in shadow. ● objects light camera

  21. Shadow Mapping Video: Shadow Mapping

  22. Main Challenges ● Tracking stability ● Limited memory and speed ● Interface-related: one hand is always holding the device ● Small community ● OpenGL ES 2.0 and GLSL sintax

  23. Future Work ● Improve shadow mapping and 2D text ● Experiment with arbitrary complex meshes ● Acquire light position in real time ● Render soft shadows ● Marker-less AR

  24. Special Thanks ● Luiz Velho ● Djalma Lucio ● Aldo Zang ● Leonardo Carvalho

  25. References ● Tangible Interfaces using Handheld Augmented Reality. P. Rojtberg and A. Olwal ● OpenGL ES specs: http://www.khronos.org/opengles/spec/ ● Understanding Virtual Reality. William R. Sherman and Alan Craig

  26. Thank you -------- tknop@impa.br www.impa.br/~tknop

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