Occlusion Culling for Wide-Angle Computer-Generated Holograms Using Phase Added Stereogram Technique

Abstract

A computer-generated hologram (CGH) allows synthetizing view of 3D scene of real or virtual objects. Additionally, CGH with wide-angle view offers the possibility of having a 3D experience for large objects. An important feature to consider in the calculation of CGHs is occlusion between surfaces because it provides correct perception of encoded 3D scenes. Although there is a vast family of occlusion culling algorithms, none of these, at the best of our knowledge, consider occlusion when calculating CGHs with wide-angle view. For that reason, in this work we propose an occlusion culling algorithm for wide-angle CGHs that uses the Fourier-type phase added stereogram (PAS). It is shown that segmentation properties of the PAS can be used for setting efficient conditions for occlusion culling of hidden areas. The method is efficient because it enables processing of dense cloud of points. The investigated case has 24 million of point sources. Moreover, quality of the occluded wide-angle CGHs is tested by two propagation methods. The first propagation technique quantifies quality of point reproduction of calculated CGH, while the second method enables the quality assessment of the occlusion culling operation over an object of complex shape. Finally, the applicability of proposed occlusion PAS algorithm is tested by synthetizing wide-angle CGHs that are numerically and optically reconstructed.

Fast 3D Content Update for Wide-Angle Holographic Near-Eye Display

“…Propagation-based techniques [20,34] are not optimal for CGHs with wide-angle, as they do not usually consider geometry where the object is much larger than the hologram. Recently, it has been shown that PAS-based algorithms enable efficient calculation of wide viewing angle CGHs [23]. The PAS algorithm is based on the principle of dividing the hologram plane into smaller segments of size N s × N s [35][36][37].…”

“…The employment of the PAS algorithm for efficient calculation of wide-angle CGHs with occlusion culling has been shown in [23], where it was shown that PAS enables efficient CGH calculations and occlusion culling of unseen areas. It was demonstrated that the occlusion-based PAS method can process CGHs with small pixel pitch (∆ = 0.62 µm), segment size N s = 512 and extension parameter q = 3.…”

“…In our case, the 3D point cloud of Neptune had a dens millimeter square. With this density and the selected geometry of the h the angular spacing of the Neptune cloud was obtained as around 0 defines the maximum size of the extended segment as 1573 pixels [23] calculations of this work, Ns = 512 and q = 3 were used. The selected for fast calculations, high accuracy, and robust occlusion culling of un…”

“…On the other hand, Ref. [23] has shown that the based-PAS algorithm is well suited for fast calculation of wide-angle view CGHs with densely populated clouds and occlusion culling of unseen areas. Despite these advantages, the PAS algorithm is still a relatively slow tool for obtaining a single high-resolution CGH for online viewpoint change.…”

“…This improves the processing time of reused information several times over. Subsequently, the missing region of the hologram is generated with the PAS algorithm [23]. The combination of these two tools enables calculation of the next viewpoint.…”