1. Enabling Beyond-Surface Interactions for Interactive Surface with An Invisible Projection Li-Wei Chan, Hsiang-Tao Wu, Hui-Shan Kao, Ju-Chun Ko, Home-Ru Lin, Mike Y. Chen, Jane Hsu, Yi-Ping Hung Department of Computer Science and Information Engineering Graduate Institute of Networking and Multimedia National Taiwan University {mikechen, yjhsu, hung}@csie.ntu.edu.tw

2. Outline Abstract Introduction Related work Design of our tabletop system Interaction design Early user response Conclusion

3. Abstract infrared(IR) marker diffused-illumination(DI) IR and standard projector

4. Introduction Enabling above-surface interaction with an invisible projection. On the tabletop, the i-m-Lamp device allows the integral projection of fine-detail content with the tabletop system.

5. Related Work Beyond-Surface Interaction Embedding Invisible Information

6. Design of Our Tabletop System Invisible Light Projector Diffuser and Glass Surfaces Marker Split and Merge Cooperating with Multi-Touch Background Simulation Marker Turnoff Enhancing Intensity of black regions in markers Software Synchronization Calibration

7. Design of Our Tabletop System(cont.) The hardware architecture of the system prototype.

8. Diffuser and Glass Surfaces Two common relative placement cases of the diffuser and touch-glass layers for a DI tabletop system. In our work, we placed the diffuser layer on top of the touch-glass layer in order to obtain the best quality for projections both from above and beneath the tabletop.

9. Diffuser and Glass Surfaces(cont.) The IR spots in the camera view due to the touch-glass layer. Two camera views are blended to obtain a spot-free image for later processing.

10. Marker Split and Merge Adapting maker size according to the observing positions of the camera. The markers selectively split and merge when the camera observes the surface (a) at a distance and (b) close-up respectively.

11. Cooperating with Multi-Touch The image processing flow of the proposed method.

12. Background Simulation The process of background simulation. Steps 1 and 2 are executed in the offline phase to collect the intensity response of projected markers. Step3 is run during the online phase to generate the simulated background of a given marker layout.

13. Enhancing Intensity of black regions in markers Three different intensity levels, from 64 and 192, of the black pixels in the markers. On the top row are the stitched view captured from beneath the surface used for on- surface detection. On the bottom row are the images from the IR camera above the surface for computing the positions.

14. Calibration The process of our semi-automatic system calibration, where the user need only to specify the four points of the tabletop display corners in the visible light projection image.

15. Interaction Design i-m-Lamp i-m-Flashlight i-m-View Implementation

16. i-m-Lamp

17. i-m-Flashlight The i-m-Flashlight device, composed of a pico-projector with an IR camera, is a mobile version of i-m-Lamp. The projection is applied with a circular mask.

18. i-m-Flashlight(cont.) The user points out an region of interest with the i-m-Flashlight where fine-detail information is presented.

19. i-m-View The i-m-View prototype device attached with an IR camera on the back side of the tablet computer.

20. i-m-View(cont.) The table boundary is attached in the i-m-View to reduce the sense of isolation between the users and the table and the content outside the boundary is purportedly darkened to enhance the presence of the table while using the i-m-View.

21. Early user response Dead reckoning More about operation

22. Conclusion This paper present a new interactive tabletop system Using invisible markers