Design, Camera And Projector-based Human-computer Interaction Systems

Human-Computer Interaction, HCI, is the research on human, computer and the interaction between them. The functions of HCI is acomplished by the In/Out equipment and related software. And the progress of HCI has made the communication between human and computer much natural, and several ways of interaction have shown up: data interaction, image interaction, voice interaction and behavior interaction. The camera-projection interaction system, based on hand movement, mentioned in this paper, is involved into the behavior interaction.Compared with other kinds of interaction systems, the camera-projection interaction system, which just contains projector, camera and computer, has simple structure and low cost, and the information is esay to be shared, so such interaction system has a broad applicational vista. However, there are still some problems, which need to be solved to bring the system into a higher advance, such as the mobility, auto-focusing of projector, auto-tracking of hand. In this paper, methods to solve three of the problems are introduced mainly.First of all, a new algorithm of the calibration between projector and camera is introduced to solve the inmobility problem and producing a normal image on the fixed screen. Less base points is used in the algorithm to calculate the three-dimensional geometry. Therefore, such method could be more efficient than the current methods. During the experiment, the change of the position of the camera, projector and screen could not affect the stability of the image, thereby not affecting the effective human-machine nteraction.Secondly, autofocus of the region of interest has been achieved in this paper, in order to meet the practical need of the screen. In practical applications, the screen could be any desktop, wall, or even the ground, so we should aviod the impact of the rough screen to the efficency of interaction. The autofocus method in this paper has three characters: using a simple calculation of focal blur to reduce the complexity of the algorithm; then inorder to get the ROI, thresholding method is proposed in the blur image to reduce the complesity; the autofocus is eventually achieved by the resonal auto-control of lens.Finally, a suitable hand tracking method is designed to meet the practical need of the system. In this system, the background is rapidly changing on the projection screen, and the image area which has the same color to hand could appear. Therefore, the traditional background subtraction method is not applicapable for the camera projection system. In the algorithm this paper presents, a new hand motion feature, which is quite different from other moving objects', is first used to determine the candidate hand area from the single-frame images: a larger value of motion residue. Then, the tracking algorithm uses the continuity of the movement of hand motion, based on the comtemperal filtering to indentify real hand trajectory, and ultimately achieve the auto location of human hand.The interactive technology proposed in this paper has these three advantages: auto-calibration is realized without resetting the system when the atmospheres change; the ROI could be auto-focusd, ignoring the screen condition; the tracking method combaining information of motion residue and color could realize the fast and prisice hand tracking, and such method has not been seen in the papers home. Therefore the camera-projection human-computer interactive system in this paper could be used broadly.