| Summary: | 碩士 === 國立臺灣大學 === 資訊工程學研究所 === 102 === Curved multi-touch screen is very useful in the purpose of exhibition and demonstration. Compared with planar screen, a curved interactive screen al- lows more users to interact simultaneously in a limited space, and makes the interior design of the exhibition room more flexible. Using a single projec- tor for the whole screen area provides a coarse scene with very low resolu- tion. In order to express more content details, we can add a high-resolution projector along with the large-area projector to project in a smaller area of user''s attention. A mirror controlled by pan-tilt-unit is installed in front of the high-resolution projector. By rotating pan and tilt angles, the high-resolution projection area can be moved to any location on the screen.
It is very challenging to calculate the projecting image that display the content correctly on a curved screen after PTU-controlled mirror reflection. Existing calibration method use the steerable projector on planar screen only. They sample some pan-tilt angles and calculate the homography between screen and projector at that angle, just like in calibration of fixed projector. When the projector rotate to un-sampled angle, they interpolate the homogra- phy from nearby sample angles. To deal with a curved screen by this method, we have to make the sample angles very close enough that the small piece of curve between them approaches planar. This significantly increases the required number of sample angles, and let the calibration procedure too time- consuming.
In this paper, we propose a new method for calibration by reconstructing the physics model of the devices, and simulate the light path of projector in 3D rendering software to get a projecting image which can project the content on the curved screen correctly. For estimating the parameters in the model, we propose a method that can do the whole procedure fast and automatically. With this method we can build a projecting system with very fast and effortless calibration.
To utilize the calibration result, we implement a program that can capture the content of other window, and warp the image by the calibrated parameters to project it correctly on the curved screen. This program also warp the IR- camera image and detect finger touches in curved screen''s 2D coordinate to send back to the interactive content application. For an interactive content designer, our program can handle all the details about the interactive display system, thus enables he or she to focus on the content development.
Key words: Multi-Resolution, Multi-Touch, Steerable Projector, Curved Display System, Geometric Calibration, Physics Model
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