Ivo Hanák

Hologram synthesis for photorealistic reconstruction.

Computation of diffraction patterns, and thus holograms, of scenes with photorealistic properties is a highly complicated and demanding process. An algorithm, based primarily on computer graphics methods, for computing full-parallax diffraction patterns of complicated surfaces with realistic texture and reflectivity properties is proposed and tested. The algorithm is implemented on single-CPU, multiple-CPU and GPU platforms. An alternative algorithm, which implements reduced occlusion diffraction patterns for much faster but somewhat lower quality results, is also developed and tested. The algorithms allow GPU-aided calculations and easy parallelization. Both numerical and optical reconstructions are conducted. The results indicate that the presented algorithms compute diffraction patterns that provide successful photorealistic reconstructions; the computation times are acceptable especially on the GPU implementations.

Detail-driven digital hologram generation

Digital holography is a technology with a potential to provide realistic 3D images. However, generation of digital holograms is a computationally demanding task. Thus, the performance is a major concern. We propose a new method that reduces spatial resolution in order to accelerate hologram generation. It employs the propagation between parallel planes for efficient optical field values evaluation and a computer graphics approach for approximating visibility. Our results show that the proposed reduction has only a minimal impact on the visual quality, while the formal computational complexity confirms performance improvement.

Full-Parallax Hologram Synthesis of Triangular Meshes using a Graphical Processing Unit

Application of the GPU to the computer generated holography is a topic of research for some time. While the majority of authors aim on performance, we aim on visual aspects. We present a new approach that is capable to synthesise a hologram of a scene described by triangles using the GPU and it is capable to respect a local intensity variation on a surface caused by textures and solve occlusion at the same time.

Acceleration of detail driven method for hologram generation

A hologram provides a scene similar to the real world, and it can be used to display a virtual scene because it can be simulated numerically. However, the simulation is a computationally extensive task. Therefore, we accelerate it by enhancing the detail driven method. The design of the original method allows us to reduce the number of samples and limit the variability of elements without restricting scene contents. The proposed enhancements neither limit the diffusiveness of a surface nor require a minimum distance between a scene and a hologram. The computation time is reduced approximately 5× in the case of a typical scene. Hence, the method is able to calculate a hologram of 4096×4096 samples from a scene of 800 triangles in about 3.1 h on a regular 2.4-GHz CPU without any special hardware. This shows flexibility of the method and indicates that the method is acceptable for practical use.

Hologram synthesis accelerated in field programmable gate array by partial quadratic interpolation

Numerical models of holograms are available but their evaluation is a very computationally intensive task. We present an acceleration algorithm for optical field synthesis suitable for the reduced occlusion method of hologram synthesis. The acceleration uses an approximation that is designed for a field programmable gate array (FPGA) and therefore it mostly uses fixed point numbers. The work describes the approximation, its fixed-point modification, and the resulting FPGA structure. The results presented show that the solution produces high-quality holograms in a significantly reduced time due to efficient FPGA implementation.

Digital HPO Hologram Rendering Pipeline

This paper describes a rendering pipeline for digital hologram synthesis. The pipeline is capable of handling triangle meshes, directional light sources, texture coordinates and advanced illumination models. Due to the huge computational requirements of hologram synthesis only the HPO holograms are considered.

HPO Hologram Synthesis for Full-Parallax Reconstruction Setup

Digital hologram synthesis is a task that simulates a physical process. Currently, there is no working solution capable of handling continuous surfaces, solving visibility, and applying a local intensity variation efficiently. Due to the computational complexity an approximation is required. Our solution tries to address this issue by extending the most efficient HPO hologram synthesis in such way that the computed hologram does not require a special optical setup for reconstruction.

Scanline rendering of digital HPO holograms and hologram numerical reconstruction

This paper presents a fast and complete rendering method that can be used for creating digital horizontal parallax only (HPO) holograms of a scene consisting of triangle mesh objects. This method solves visibility and occlusion problems and is capable of working with triangles as the basic primitive instead of the usually used points. It is fast because it avoids the direct distance computation using the square root operation. Advanced numerical reconstruction techniques are used for presenting the results of the rendering method.