An Effective Method for Movable Projector Keystone Correction

Keystone correction is an essential operation for projector-based applications, especially in mobile scenarios. In this paper, we propose a handheld movable projection method that can freely project keystone-free content on a general flat surface without adding any markings or boundary on it. Such a projection system can give the user greater freedom of display control (such as viewing angle, distance, etc.), without suffering from keystone distortion. To achieve this, we attach a camera to the projector to form a camera-projector pair. A green frame with the same resolution as the projector screen is projected onto the screen. Particle filter is employed to track the green frame and the correction of the display content is then achieved by rectifying the projection region of interest into a rectangular area. We built a prototype system to validate the effectiveness of the method. Experimental results show that our method can continuously project distortion free content in real time with good performance.