Rapid Generation Method Of Computer-generated Holograms Based On The Ray-tracing Technics

Three-dimensional(3D)display technology has made great progress in the past few years.Among the various 3D display methods,holographic displays can reconstruct the complete optical wave field of a 3D scene.In addition to the optical amplitude of traditional images,holographic displays can also reproduce the phase information of light to express depth perception.However,generating traditional computer-generated holograms(CGHs)requires significant computing time.In this paper,ray tracing is used to realize the rapid generation of CGH.The backward ray-tracing technique is able to render photorealistic high-quality images,which noticeably reduce the computation time achieved from the high-degree parallelism of Graphics Processing Units(GPUs).Firstly,a high-efficiency photorealistic CGHs method is presented based on the ray-tracing technique.Rays are parallelly launched and traced under different illuminations and circumstances to calculate the complex amplitude at the hologram plane.Experimental results demonstrate the effectiveness of the proposed method.Compared with the traditional point cloud CGH,the computation time is decreased to 24 seconds to reconstruct a 3D object of 100×100 rays with continuous depth change.Secondly,a real-time CGH method is presented based on backward ray tracing and wavefront recording planes(WRPs).Rays are parallelly launched and traced to obtain ray-object intersections,and then the complex wave field of the effective pixels in the WRP is determined.The complex amplitude at the hologram plane is generated by the Fresnel diffraction integral calculation from the WRP to the hologram plane using fast Fourier transform(FFT)and inverse fast Fourier transform(IFFT)algorithms,then,a CGH is generated by coding.Through a phase spatial light modulator(SLM),optical dynamic 3D objects are reconstructed.Compared with traditional CGHs,the rate of CGH generation and optical reconstruction improves to 35.6 frames per second(FPS),achieving the real-time rendering and interactivity.