Concave micro-mirror arrays fabricated as holographic optical elements are used in projector-based light field displays due to their see-through characteristics. The optical axes of each micro-mirror in the array are usually made parallel to each other, which simplifies the fabrication, integral image rendering, and calibration process. However, this demands that the beam from the projector be collimated and made parallel to the optical axis of each elemental micro-mirror. This requires additional collimation optics, which puts serious limitations on the size of the display. In this Letter, we propose a solution to the above issue by introducing a new method to fabricate holographic concave micro-mirror array sheets and explain how they work in detail. 3D light field reconstructions of the size 20 cm×10 cm and 6 cm in depth are achieved using a conventional projector without any collimation optics.
This paper presents the augmentation of immersive omnidirectional video with realistically lit objects. Recent years have known a proliferation of real-time capturing and rendering methods of omnidirectional video. Together with these technologies, rendering devices such as Oculus Rift have increased the immersive experience of users. We demonstrate the use of structure from motion on omnidirectional video to reconstruct the trajectory of the camera. The position of the car is then linked to an appropriate 360 • environment map. State-of-the-art augmented reality applications have often lacked realistic appearance and lighting. Our system is capable of evaluating the rendering equation in real-time, by using the captured omnidirectional video as a lighting environment. We demonstrate an application in which a computer generated vehicle can be controlled through an urban environment.
Recent advances in the creation of microlens arrays as holographic optical elements (HOEs) allow the creation of projector based see-through light field displays suitable for augmented reality. These systems require an accurate calibration of the projector with relation to the microlens array, as any small misalignment causes the 3D reconstruction to fail. The methods reported so far, require precise placement of the calibration camera w.r.t the lens array screen, which affects the display configuration. We propose a calibration approach which is more robust, and which allows free camera placement. Hence, it does not limit the capabilities of the system. Both a homography based technique and structured light play a central role in realizing such a method. The method was tested on a projection based integral imaging display system consisting of a consumer-grade projector and a digitally designed holographic optical element (DDHOE) based micromirror array screen. The calibration method compensates for the lens distortion, intrinsics and positioning of the projector with relation to the screen. The method uses a single camera and doesn't require the use of obtrusive markers as reference. We give an in-depth explanation of the different steps of the algorithm, and verify the calibration using both a simulated and a real-world setup.
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