Efficient rendering by parallelogram-approximation for full analytical polygon-based computer-generated holography using planar texture mapping

Viewpoint-dependent lighting on polygonal holograms using bump mapping

Holograms can be observed from different viewpoints, because light waves can be encoded to propagate in multiple directions. Thus, accurate holograms for 3D display should model viewpoint-dependent light reflections. We proposed a new, to the best of our knowledge, hologram generation method for objects represented by polygonal meshes, whose lighting changes as the viewer moves, all while rendering smooth shading using low-poly objects. The proposed method leverages bump mapping and converts it into a bump-phase map encoding the propagation frequency and then spreads the reflected light wave so that only a specific viewpoint can receive them. Simulation experiments with small pixel pitches confirm the method's high computational performance.

Rendering of 3D scenes in analytical polygon-based computer holography with texture mapping

A computer-generated hologram (CGH) is a technique that generates an object light field by superimposing elementary holograms. Unlike traditional holography, this technique does not require the generation of an additional reference light to interfere with the calculated object light field. Texture mapping is a method that enhances the realism of 3D scenes. A fast method is presented that allows users to render holograms of 3D scenes consisting of triangular meshes with texture mapping. All calculations are performed with analytical expressions to ensure that the holograms generated by this method are fast and can reconstruct three-dimensional scenes with high quality. Using this method, a hologram of a three-dimensional scene consisting of thousands of triangles is generated. Our algorithm generates the same reconstruction results as those of Kim et al. [Appl. Opt.47, D117 (2008)APOPAI0003-693510.1364/AO.47.00D117], but significantly reduces the computation time (the computation time of our algorithm is only one-third of that of Kim et al.'s algorithm). The results show that the proposed method is computationally efficient as compared to a previous work. The proposed method is verified by simulations and optical experiments.

Realistic rendering method for specular reflections with continuous motion parallax in a computer-generated hologram

A computer-generated hologram (CGH) enables the display of virtual images and videos as well as the communication and storage of holographic data. The point-based method, which is a CGH-calculation method for representing the surface of an object as a set of point-light sources, has not been sufficiently studied in terms of realistic representation. This paper proposes a CGH-calculation method for realistic rendering using ray tracing to be used with a point-based method. Experiments were conducted with an optical system to confirm the effectiveness of the proposed method in terms of hidden-surface removal in mirror images and its implementation on multiple mirror surfaces. The results indicate that the proposed method enabled hidden-surface removal with continuous parallax and reflection on mirror surfaces.