Fast calculation of full-parallax computer-generated holograms for holographic three-dimensional display based on OpenGL shaders

Holographic three-dimensional (3D) display is one of the current research hotspots in the field of true 3D display. It records and reconstructs the wavefront information of a 3D scene, and is able to provide all the depth cues required by the human eye. The point-source method is the most accurate way to calculate computer-generated holograms (CGHs) for holographic 3D display. However, it usually needs a lot of computation, especially when calculating full-parallax CGHs, which requires rendering the 3D scene from each perspective and superposition of complex amplitudes from the point sources for each pixel on the hologram plane. Serial calculation using central processing units (CPUs) is timeconsuming and difficult to meet actual demands. In this paper, OpenGL shaders are utilized to realize fast calculation of CGHs. Taking advantage of the highly parallel architecture of the graphics processing unit (GPU), OpenGL shaders are used to process the data of 3D objects, compute amplitudes of the sampling points, and implement superposition and phase extraction in parallel. Finally, Phase-only holograms are obtained by this method. Images of the scene are reconstructed from the generated holograms to verify the correctness of the proposed method. Comparing the time taken by MATLAB and OpenGL to generate holograms of three different 3D models under the same conditions, the calculation method based on OpenGL shaders proposed in this paper can significantly shorten the computation time. The computation speed is increased by up to 600 times. It is expected to achieve real-time calculation of full-parallax CGHs and promote practical applications of holographic 3D display.