Projection Mapping with a Brightly Lit Surrounding Using a Mixed Light Field Approach.

Projection mapping (PM) exhibits suboptimal performance in well-lit environments because of the interference caused by ambient light. This interference degrades the contrast of the projected images. Consequently, conventional methodologies restrict the application of PM to dimly lit settings, leading to an unnatural visual experience, as only the PM target is prominently illuminated. To overcome these limitations, we introduce an innovative approach that leverages a mixed light field, blending traditional PM with ray-controllable ambient lighting. This methodological combination, despite its simplicity, is effective because it ensures that the projector exclusively illuminates the PM target, preserving the optimal contrast. Precise control of ambient light rays is essential to prevent them from illuminating the PM target while adequately illuminating the surrounding environment. Furthermore, we propose the integration of a kaleidoscopic array with integral photography to generate dense light fields for ray-controllable ambient lighting. Additionally, we present an efficient binary-search-based calibration method tailored to this intricate optical system. Our optical simulations and the developed system collectively validate the effectiveness of our approach. Our results show that PM targets and ordinary objects coexist naturally in environments that are brightly lit as a result of our method, enhancing the overall visual experience.

Wide viewing angle with a downsized system in projection-type integral photography by using curved mirrors.

To obtain a large viewing angle in conventional projection-type integral photography frameworks, multiple projectors need to be arranged at a particular angle to a lens array. Hence, the systems require a large space. This paper proposes a system that achieves a large viewing angle in a space-saving manner by using curved mirrors that face each other. To this end, a projector is placed directly behind a lens array, and curved mirrors are installed to surround the rays from the projector. The incident angle toward the lens array increases after there are multiple reflections between the mirrors, which increases the viewing angle. In addition, it is not necessary to install the projector at an angle to the lens array, which results in a space-saving system. With the proposed method, a viewing angle of ±60 deg can be achieved.

Occlusion-robust sensing method by using the light-field of a 3D display system toward interaction with a 3D image.

The recent developments in 3D display technology are remarkable. Owing to such developments, the importance of methods for interacting with 3D images has been increasing. In particular, the ability to perform input operations by directly touching displayed images is important. Therefore, a sensing method is required for recognizing the 3D positions of fingers and determining whether the fingers are touching the 3D image displayed. Conventionally, such a sensing method generally involves position sensing of fingers through image-based active sensing. However, this does not solve the following two problems: (1) the problem of positional registration, that is, the accurate matching between the displayed image and input location, and (2) the problem of occlusion robustness, that is, the achievement of successful sensing even with the presence of an occluding object between the sensor and hands to allow free movement of the hands. Our proposed method solves these problems through the following two ideas. First, we used a method called aerial imaging by retroreflection, which focuses light rays from a wider range than other 3D display systems. Second, for capturing the reflected light as well as projecting to the sensing target in active sensing, we used the light-field formed by the 3D display system. We also propose a method for obtaining rotation information, considering that the light-field formed by the reflected light changes based on the angle of the sensing target. Simulations and experiments were performed to evaluate the proposed system, and the system setup was optimized through simulations. In the first two experiments conducted on position and rotation sensing, we evaluated the sensing errors due to occlusion and found them to be less than 1.74 mm and less than 15.4 deg, respectively. In the third experiment, we constructed an interaction system with 3D images by using the proposed method and evaluated this system.