Smooth motion parallax method for 3D light-field displays with a narrow pitch based on optimizing the light beam divergence angle.

The three-dimensional (3D) light field display (LFD) with dense views can provide smooth motion parallax for the human eye. Increasing the number of views will widen the lens pitch, however, resulting in a decrease in view resolution. In this paper, an approach to smooth motion parallax based on optimizing the divergence angle of the light beam (DALB) for 3D LFD with narrow pitch is proposed. DALB is controlled by lens design. A views-fitting optimization algorithm is established based on a mathematical model between DALB and view distribution. Subsequently, the lens is reversely designed based on the optimization results. A co-designed convolutional neural network (CNN) is used to implement the algorithm. The optical experiment shows that a smooth motion parallax 3D image is achievable through the proposed method.

Vertically spliced tabletop light field cave display with extended depth content and separately optimized compound lens array.

Tabletop three-dimensional light field display is a kind of compelling display technology that can simultaneously provide stereoscopic vision for multiple viewers surrounding the lateral side of the device. However, if the flat panel light field display device is simply placed horizontally and displayed directly above, the visual frustum will be tilted and the 3D content outside the display panel will be invisible, the large oblique viewing angle will also lead to serious aberrations. In this paper, we demonstrate what we believe to be a new vertical spliced light field cave display system with an extended depth content. A separate optimization of different compound lens array attenuates the aberration from different oblique viewing angles, and a local heating fitting method is implemented to ensure the accuracy of fabrication process. The image coding method and the correction of the multiple viewpoints realize the correct construction of spliced voxels. In the experiment, a high-definition and precisely spliced 3D city terrain scene is demonstrated on the prototype with a correct oblique perspective in 100-degree horizontal viewing range. We envision that our research will provide more inspiration for future immersive large-scale glass-free virtual reality display technologies.

[Research progress on biological characteristics and propagation technology of Atractylodes lancea].

Atractylodes lancea is a perennial herb of the Asteraceae family and is one of the well-known traditional Chinese medicine(TCM). Several studies have documented polyene alkyne and sesquiterpenoid compounds as the main bioactive compounds of A. lancea, especially atractylodin, atractylon, ß-eudesmol, and hinesol in its rhizomes, which possess anti-virus, anti-inflammation, hypoglycemic, anti-hypoxia, liver protection, and diuresis activities. In parallel with the recent advancements in biotechnology, important achievements have been made in the study of biological characteristics and propagation technology of A. lancea. This study reviews the research progress on morphological features, cytogenetics, ecological planting, effective ingredients, and tissue culture techniques of A. lancea from the biology perspective, so as to provide a theoretical basis for reasonable development of A. lancea resources.

[Comparative analysis of plastomes of Rubus chingii and R. chingii var. suavissimus].

Rubus chingii and R. chingii var. suavissimus are unique dual-purpose plant resources, with significant nutraceutical, pharmaceutical, and economic value, as well as promising prospects for further development. To investigate the genetic structure and evolutionary characteristics of these two varieties, this study conducted plastome sequencing using the Illumina HiSeq XTen sequencing platform. Subsequently, the study performed assembly, annotation, and characterization of the genomes, followed by a comparative plastome and phylogenetic analysis using bioinformatics techniques. The results revealed that the plastomes of R. chingii and R. chingii var. suavissimus exhibited a tetrad structure, comprising a large single-copy region(LSC), a small single-copy region(SSC), and two inverted repeat regions(IRs). The study identified a total of 56 simple sequence repeats(SSRs) after comparative analysis, predominantly consisting of A and T. Furthermore, the structure of the IR boundary genes in both varieties was found to be highly conserved, with only minor nucleotide variations. Additionally, the study identified three highly variable regions: rps16-trnQ-psbK, trnR-atpA, and trnT-trnL, which held promise as potential identification marks for further development and utilization. Phylogenetic analysis results obtained by the maximum likelihood and Bayesian inference methods demonstrated a close clustering of R. chingii and R. chingii var. suavissimus(100% support), with their closest relatives being R. trianthus. This study, focusing on plastome-level genetic distinctions between these two varieties, lays a foundation for future species protection, development, and utilization.

[Correlations between tanshinones and soil factors of Salviae Miltiorrhizae Radix et Rhizoma from different producing areas].

Soil nutrients and inorganic elements affect not only the growth and development of medicinal plants but also the formation and accumulation of active ingredients in traditional Chinese medicines. The content of tanshinones and 28 inorganic elements in Salviae Miltiorrhizae Radix et Rhizoma samples from 18 producing areas in 6 provinces was determined, and 35 physical and chemical properties of the corresponding soil samples were determined. The enrichment characteristics of inorganic elements in Salviae Miltiorrhizae Radix et Rhizoma were analyzed. The correlation analysis and stepwise regression analysis were performed to screen out the main soil factors affecting the content of tanshinones in Salviae Miltiorrhizae Radix et Rhizoma. The results showed that the content of tanshinones in the samples from different areas varied significantly, being the highest in the samples from Shandong, the second in the samples from Henan, and low in the samples from Shanxi and Sichuan. K, Mg, Ca, and Na were rich in Salviae Miltiorrhizae Radix et Rhizoma samples, among which Na and K had the highest enrichment coefficients. The results of correlation and regression analyses showed that soil K, Na, Ti, and total nitrogen were the main soil factors affecting the tanshinones in Salviae Miltiorrhizae Radix et Rhizoma. Specifically, the content of tanshinones was positively correlated with Ti and negatively correlated with Na, K, and total nitrogen in the soil. Therefore, during the planting of Salvia miltiorrhiza, the land should be selected with full consideration to the salinity and saline land should be avoided. Secondly, the application of nitrogen and potassium fertilizers can be appropriately reduced, and water-soluble elemental fertilizers for S. miltiorrhiza should be developed.

[Effect of combined application of organic and chemical fertilizers on yield and quality of Epimedium pubescens].

To investigate the effects of different ratios of organic and chemical fertilizers on the yield and quality of Epimedium pubescens,so as to provide a scientific basis for the fertilization of high-yield and high-quality E. pubescens cultivation. In this experiment,a field plot test was conducted,and CK(without fertilizer) was set as the control group,with five treatment groups with different ratios of organic fertilizers and chemical fertilizers set up,namely OF0(100% chemical fertilizers),OF25(25% organic fertilizers),OF50(50% organic fertilizers),OF75(75% organic fertilizers),and OF100(100% organic fertilizers). The effects of different fertilization patterns on the agronomic traits,yield,effective component content,nutrient accumulation,and soil physicochemical properties of E. pubescens were determined,and the yield and quality of the medicinal herb were comprehensively evaluated by using the CRITIC weights method. It was found that the herb yield of each treatment group was significantly increased compared with the CK group,although the yield of the groups with both organic fertilizer and chemical fertilizer was slightly lower than that of OF0. However,there was no significant difference,which indicated that the organic fertilizer combined with chemical fertilizer could ensure the herb yield. With the increase in organic fertilizer ratios,the medicinal components epimedin A,epimedin B,and epimedin C showed a tendency of first increasing and then decreasing,with the highest content in the OF25,while icariin showed a rising trend,with the best in the OF100. However,overall,the total flavonol glycosides ABCI accumulated the most in the OF25. The results of the CRITIC method showed that the top three fertilization treatments in terms of the comprehensive scores of the medicinal herb were OF25,OF50,and OF75. Organic fertilizer combined with chemical fertilizer is conducive to improving the soil's fertilizer holding and supply capacity,and the soil indexes are optimal in OF100. The soil enzyme activity is the highest in OF75. Meanwhile,organic fertilizer combined with chemical fertilizer can help the plant's uptake and accumulation of nutrients,and OF25 shows the most obvious effect.By comprehensively considering the influence of different ratios of organic and chemical fertilizers on the yield,effective component content,nutrient accumulation,and other indexes of E. pubescens,it is recommended that a 25% ratio(7 500 kg·hm~(-2)) of organic fertilizers and chemical fertilizers should be used in E. pubescens production in the first year,so as to promote the E. pubescens industry to increase yield and improve quality.

[Mechanism and application prospects of microbial fertilizers in regulating quality formation of medicinal plants].

With the promotion of chemical fertilizer and pesticide reduction and green production of traditional Chinese medicines, microbial fertilizers have become a hot way to achieve the zero-growth of chemical fertilizers and pesticides, improve the yield and qua-lity of medicinal plants, maintain soil health, and promote the sustainable development of the planting industry of Chinese herbal medicines. Soil conditions and microenvironments are crucial to the growth, development, and quality formation of medicinal plants. Microbial fertilizers, as environmentally friendly fertilizers acting on the soil, can improve soil quality by replenishing organic matter and promoting the metabolism of beneficial microorganisms to improve the yield and quality of medicinal plants. In this regard, understanding the mechanism of microbial fertilizer in regulating the quality formation of medicinal plants is crucial for the development of herbal eco-agriculture. This study introduces the processes of microbial fertilizers in improving soil properties, participating in soil nutrient cycling, enhancing the resistance of medicinal plants, and promoting the accumulation of medicinal components to summarize the mechanisms and roles of bacterial fertilizers in regulating the quality formation of medicinal plants. Furthermore, this paper introduces the application of bacterial fertilizers in medicinal plants and makes an outlook on their development, with a view to providing a scientific basis for using microbial fertilizers to improve the quality of Chinese herbal medicines, improve the soil environment, promote the sustainable development of eco-agriculture of traditional Chinese medicine, and popularize the application of microbial fertilizers.

Image edge smoothing method for light-field displays based on joint design of optical structure and elemental images.

Image visual quality is of fundamental importance for three-dimensional (3D) light-field displays. The pixels of a light-field display are enlarged after the imaging of the light-field system, increasing the graininess of the image, which leads to a severe decline in the image edge smoothness as well as image quality. In this paper, a joint optimization method is proposed to minimize the "sawtooth edge" phenomenon of reconstructed images in light-field display systems. In the joint optimization scheme, neural networks are used to simultaneously optimize the point spread functions of the optical components and elemental images, and the optical components are designed based on the results. The simulations and experimental data show that a less grainy 3D image is achievable through the proposed joint edge smoothing method.

Real-time light-field generation based on the visual hull for the 3D light-field display with free-viewpoint texture mapping.

Real-time dense view synthesis based on three-dimensional (3D) reconstruction of real scenes is still a challenge for 3D light-field display. It's time-consuming to reconstruct an entire model, and then the target views are synthesized afterward based on volume rendering. To address this issue, Light-field Visual Hull (LVH) is presented with free-viewpoint texture mapping for 3D light-field display, which can directly produce synthetic images with the 3D reconstruction of real scenes in real-time based on forty free-viewpoint RGB cameras. An end-to-end subpixel calculation procedure of the synthetic image is demonstrated, which defines a rendering ray for each subpixel based on light-field image coding. In the ray propagation process, only the essential spatial point of the target model is located for the corresponding subpixel by projecting the frontmost point of the ray to all the free-viewpoints, and the color of each subpixel is identified in one pass. A dynamic free-viewpoint texture mapping method is proposed to solve the correct graphic texture considering the free-viewpoint cameras. To improve the efficiency, only the visible 3D position and texture that contributes to the synthetic image are calculated based on backward ray tracing rather than computing the entire 3D model and generating all elemental images. In addition, an incremental calibration method by dividing camera groups is proposed to satisfy the accuracy. Experimental results show the validity of our method. All the rendered views are analyzed for justifying the texture mapping method, and the PSNR is improved by an average of 11.88dB. Finally, LVH can achieve a natural and smooth viewing effect at 4K resolution and the frame rate of 25 ∼ 30fps with a large viewing angle.

Portrait stylized rendering for 3D light-field display based on radiation field and example guide.

With the development of three-dimensional (3D) light-field display technology, 3D scenes with correct location information and depth information can be perceived without wearing any external device. Only 2D stylized portrait images can be generated with traditional portrait stylization methods and it is difficult to produce high-quality stylized portrait content for 3D light-field displays. 3D light-field displays require the generation of content with accurate depth and spatial information, which is not achievable with 2D images alone. New and innovative portrait stylization techniques methods should be presented to meet the requirements of 3D light-field displays. A portrait stylization method for 3D light-field displays is proposed, which maintain the consistency of dense views in light-field display when the 3D stylized portrait is generated. Example-based portrait stylization method is used to migrate the designated style image to the portrait image, which can prevent the loss of contour information in 3D light-field portraits. To minimize the diversity in color information and further constrain the contour details of portraits, the Laplacian loss function is introduced in the pre-trained deep learning model. The three-dimensional representation of the stylized portrait scene is reconstructed, and the stylized 3D light field image of the portrait is generated the mask guide based light-field coding method. Experimental results demonstrate the effectiveness of the proposed method, which can use the real portrait photos to generate high quality 3D light-field portrait content.

360-degree directional micro prism array for tabletop flat-panel light field displays.

Tabletop light field displays are compelling display technologies that offer stereoscopic vision and can present annular viewpoint distributions to multiple viewers around the display device. When employing the lens array to realize the of integral imaging tabletop light field display, there is a critical trade-off between the increase of the angular resolution and the spatial resolution. Moreover, as the viewers are around the device, the central viewing range of the reconstructed 3D images are wasteful. In this paper, we explore what we believe to be a new method for realizing tabletop flat-panel light field displays to improve the efficiency of the pixel utilization and the angular resolution of the tabletop 3D display. A 360-degree directional micro prism array is newly designed to refract the collimated light rays to different viewing positions and form viewpoints, then a uniform 360-degree annular viewpoint distribution can be accurately formed. In the experiment, a micro prism array sample is fabricated to verify the performance of the proposed tabletop flat-panel light field display system. One hundred viewpoints are uniformly distributed in the 360-degree viewing area, providing a full-color, smooth parallax 3D scene.

True-color light-field display system with large depth-of-field based on joint modulation for size and arrangement of halftone dots.

A true-color light-field display system with a large depth-of-field (DOF) is demonstrated. Reducing crosstalk between viewpoints and increasing viewpoint density are the key points to realize light-field display system with large DOF. The aliasing and crosstalk of light beams in the light control unit (LCU) are reduced by adopting collimated backlight and reversely placing the aspheric cylindrical lens array (ACLA). The one-dimensional (1D) light-field encoding of halftone images increases the number of controllable beams within the LCU and improves viewpoint density. The use of 1D light-field encoding leads to a decrease in the color-depth of the light-field display system. The joint modulation for size and arrangement of halftone dots (JMSAHD) is used to increase color-depth. In the experiment, a three-dimensional (3D) model was constructed using halftone images generated by JMSAHD, and a light-field display system with a viewpoint density of 1.45 (i.e. 1.45 viewpoints per degree of view) and a DOF of 50 cm was achieved at a 100 ° viewing angle.

Induction and metabolomic analysis of hairy roots of Atractylodes lancea.

Atractylodes lancea is an important source of traditional Chinese medicines. Sesquiterpenoids are the key active compounds in A. lancea, and their presence determines the quality of the material. Hairy hoot (HR) culture is a potential method to produce medicinally active compounds industrially; however, the induction and metabolic profiling of A. lancea HR have not been reported. We found that optimal induction of A. lancea HR was achieved by Agrobacterium rhizogenes strain C58C1 using the young leaves of tissue culture seedlings in the rooting stage as explants. Ultra-performance liquid chromatography-tandem mass spectrometric analyses of the chemical compositions of HR and normal root (NR) led to the annotation of 1046 metabolites. Over 200 differentially accumulated metabolites were identified, with 41 found to be up-regulated in HR relative to NR and 179 down-regulated in HR. Specifically, atractylodin levels were higher in HR, while the levels of ß-eudesmol and hinesol were higher in NR. Metabolic pathway analyses showed a significant difference in metabolites of the shikimate acid pathway between HR and NR. Five A. lancea compounds are potential biomarkers for evaluation of HR and NR quality. This study provides an important reference for the application of HR for the production of medicinally active compounds. KEY POINTS: • We established an efficient protocol for the induction of HR in A. lancea • HR was found to have a significantly higher amount of atractylodin than did NRs • Metabolic pathway analyses showed a significant difference in metabolites of the shikimate acid pathway between HR and NR.

D-shaped photonic crystal fiber sensor based on the surface plasmon resonance effect for refractive index detection.

In this paper, a photonic crystal fiber (PCF) sensor based on the surface plasmon resonance (SPR) effect for refractive index (RI) detection is proposed. We design a D-shaped polished PCF structure consisting of air holes arranged in a hexagonal lattice. The silver film is coated on the middle channel of the polished surface of the PCF. The finite element method is used to analyze the propagation characteristics of the proposed D-shaped SPR-PCF sensor. Simulation results show that the proposed D-shaped SPR-PCF sensor has a maximum wavelength sensitivity of 30,000 nm/RIU, an average wavelength sensitivity of 6785.71 nm/RIU, and a maximum resolution of 3.33×10-6 R I U in the RI range of 1.22-1.36. Owing to the high wavelength sensitivity in the considered RI range, the proposed D-shaped SPR-PCF sensor is suitable for applications in water contamination detection, liquid concentration measurement, food safety monitoring, etc.

First Report of Pectobacterium aroidearum Causing Soft Rot of Pinellia ternata in China.

Pinelliae rhizoma is the dried tuber of Pinellia ternata (Thunb.) Breit., and has been used for thousand of years in traditional Chinese medicine as an antivomit, anticough, and analgesic (Ying et al. 2007). In September 2022, P. ternata planted in Bijie, Guizhou Province, showed severe soft rot symptoms with incidence of about 50%. The diseased plants showed water-soaked symptoms and produced a foul soft rot smell, and finally the whole plant collapsed. Lesions were first observed at the tip of a leaf or wound, and symptoms of the disease spread rapidly, with the entire plant collapsing and dying within a week. The tissue sections of six plants with typical symptoms from the diseased field were disinfected with 75% ethanol for 30 seconds and 0.3% NaClO for 3 minutes. The tissue sections were then washed with sterile water for three times. A small piece of tissue (5x5mm) was removed from the edge of the lesion and mashed in a 1.5 ml centrifuge tube containing 20 µl of sterile water. The tissue liquid was then diluted 100 times with prepared sterile water. The bacteria were streaked on LB (tryptone/yeast extract/NaCl) AGAR medium and cultured at 37°C for 48 h (Kravitz, 1962). Isolated colonies were streaked on Luria-Bertani (LB) AGAR medium to obtain single colonies for further identification. A total of 13 representative isolates were selected for PCR amplification using primers targeting the conserved region of the 16S rDNA gene, which were in turn analyzed via the BLASTn search engine on the NCBI website. The results of the analysis revealed that seven of the isolates were similar to P. aroidearum strain SCRI 109 (GenBank accession no. NR_159926), with strain BX13 exhibiting the highest similarity to P. aroidearum (99.93% similarity), and therefore, this strain was selected for further investigation. The strain BX13 was incubated on LB solid medium for 24 h at 37 °C, and the single colonies were creamy white, translucent and round, slightly elevated in the center, with smooth surfaces and neat edges (Figure S1 B1). Then,the Scanning Electron Microscope revealed that the thalli of strain BX13 were short rod-shaped and somewhat blunt round at both ends (Figure S1 B2). The steward genes (icdA, gapA, proA) of BX13 were amplified and sequenced for further identification. The sequences of the amplified fragments were all deposited in GenBank 16S rDNA (OQ874505,) icdA (OQ954122)，gapA (OQ954123), proA (OQ954124). Sequence analysis using the BLASTn program at the NCBI revealed gene icdA, gapA, and proA had 100% identity to P. aroidearum strain QJ002 (GenBank accession no. CP090597).. Meanwhile, a maximum likelihood phylogenetic tree was constructed based on multigene sequence analysis of BX13 16S rDNA and steward genes (gapA, icdA, proA) by MEGA X (Liang et al. 2022). Phylogenetic results also showed that BX13 and P. aroidearum strain QJ002 gathered in the same clade(Figure S2). Accordingly, the morphological and molecular characteristics of strain BX13 indicate that it is P. aroidearum. (Nabhan S., et al.2013,Xu et al. 2020). In order to confirm the pathogenicity of strain BX13, a bacterial suspension containing 107 CFU/ml (10 ml/ inoculation point) was injected into the base of a one-week-old P. ternata stems, control seedlings were inoculated with sterile water, inoculated and control seedlings (each of six plants) were kept in a growth chamber maintained at 26°C with a relative humidity range of 70% to 80%. Plants were watered as needed. After 3 days, the stem base of the plants inoculated with bacteria solution showed water-soaked necrosis and stems began to rot, while the plants inoculated with water did not show this symptom. The strains were then successfully re-isolated from the symptomatic P. ternata. Then the strain re-isolated was identified using the BLASTn program at the NCBI and found that it has the same 16S rDNA, icdA, gapA, and proA sequences as strain BX13, thus completing the Koch's postulates. To our knowledge, this is the first report of P. aroidearum causing P. ternata soft rot in China, which expands its known host range. Accordingly, this study provides essential information for the breeding of P. ternata resistant to bacterial soft rot and the development of control measures in China.

[DUS testing guidelines for new varieties of Chinese medicinal plants].

A rich diversity of wild medicinal plant resources is distributed in China, but the breeding of new plant varieties of Chinese medicinal plants started late and the breeding level is relatively weak. Chinese medicinal plant resources are the foundation for new varieties breeding, and the plant variety rights(PVP) are of great significance for the protection and development of germplasm resources. However, most Chinese medicinal plants do not have a distinctness, uniformity, and stability(DUS) testing guideline. The Ministry of Agriculture and Rural Affairs has put 191 plant species(genera) on protection lists, of which only 30 are medicinal species(genera). At the same time, only 29 of 293 species(genera) plants in the Protection List of New Plant Varieties of the People's Republic of China(Forest and Grass) belong to Chinese medicinal plants. The number of PVP applications and authorization of Chinese medicinal plants is rare, and the composition of variety is unreasonable. Up to now, 29 species(genera) of DUS test guidelines for Chinese medicinal plants have been developed. Some basic problems in the breeding of new varieties of Chinese medicinal plants have appeared, such as the small number of new varieties and insufficient utilization of Chinese medicinal plant resources. This paper reviewed the current situation of breeding of new varieties of Chinese medicinal plants and the research progress of DUS test guidelines in China and discussed the application of biotechnology in the field of Chinese medicinal plant breeding and the existing problems in DUS testing. This paper guides the further application of DUS to protect and utilize the germplasm resources of Chinese medicinal plants.

[Application of tissue culture technology of medicinal plants in sustainable development of Chinese medicinal resources].

Chinese medicinal resources are the cornerstone of the sustainable development of traditional Chinese medicine industry. However, due to the fecundity of species, over-exploitation, and limitations of artificial cultivation, some medicinal plants are depleted and even endangered. Tissue culture, a breakthrough technology in the breeding of traditional Chinese medicinal materials, is not limited by time and space, and can allow the production on an annual basis, which plays an important role in the protection of Chinese medicinal resources. The present study reviewed the applications of tissue culture of medicinal plants in the field of Chinese medicinal resources, including rapid propagation of medicinal plant seedlings, breeding of novel high-yield and high-quality cultivars, construction of a genetic transformation system, and production of secondary metabolites. Meanwhile, the current challenges and suggestions for the future development of this field were also proposed.

[Research progress in microevolutionary process of excellent traits and quality of Dao-di herbs].

Dao-di herbs are the treasure of Chinese materia medica and one of the characteristic research objects of traditional Chinese medicine(TCM). Probing into the microevolution of Dao-di herbs can help to reveal their biological essence and quality formation mechanisms. The progress in molecular biology and omics provides the possibility to elucidate the phylogenetic and quality forming characteristics of Dao-di herbs at the molecular level. In particular, genomics serves as a powerful tool to decipher the genetic origins of Dao-di herbs, and molecular markers have been widely used in the research on the genetic diversity and population structure of Dao-di herbs. Focusing on the excellent traits and quality of Dao-di herbs, this paper reviews the studies about the microevolution process of quality formation mechanisms of Dao-di herbs with the application of molecular markers and omics, aiming to underpin the protection and utilization of TCM resources.

Real-time realistic computer-generated hologram with accurate depth precision and a large depth range.

Holographic display is an ideal technology for near-eye display to realize virtual and augmented reality applications, because it can provide all depth perception cues. However, depth performance is sacrificed by exiting computer-generated hologram (CGH) methods for real-time calculation. In this paper, volume representation and improved ray tracing algorithm are proposed for real-time CGH generation with enhanced depth performance. Using the single fast Fourier transform (S-FFT) method, the volume representation enables a low calculation burden and is efficient for Graphics Processing Unit (GPU) to implement diffraction calculation. The improved ray tracing algorithm accounts for accurate depth cues in complex 3D scenes with reflection and refraction, which is represented by adding extra shapes in the volume. Numerical evaluation is used to verify the depth precision. And experiments show that the proposed method can provide a real-time interactive holographic display with accurate depth precision and a large depth range. CGH of a 3D scene with 256 depth values is calculated at 30fps, and the depth range can be hundreds of millimeters. Depth cues of reflection and refraction images can also be reconstructed correctly. The proposed method significantly outperforms existing fast methods by achieving a more realistic 3D holographic display with ideal depth performance and real-time calculation at the same time.

Fast virtual view synthesis for an 8K 3D light-field display based on cutoff-NeRF and 3D voxel rendering.

Three-dimensional (3D) light-field displays can provide an immersive visual experience, which has attracted significant attention. However, the generating of high-quality 3D light-field content in the real world is still a challenge because it is difficult to capture dense high-resolution viewpoints of the real world with the camera array. Novel view synthesis based on CNN can generate dense high-resolution viewpoints from sparse inputs but suffer from high-computational resource consumption, low rendering speed, and limited camera baseline. Here, a two-stage virtual view synthesis method based on cutoff-NeRF and 3D voxel rendering is presented, which can fast synthesize dense novel views with smooth parallax and 3D images with a resolution of 7680 × 4320 for the 3D light-field display. In the first stage, an image-based cutoff-NeRF is proposed to implicitly represent the distribution of scene content and improve the quality of the virtual view. In the second stage, a 3D voxel-based image rendering and coding algorithm is presented, which quantify the scene content distribution learned by cutoff-NeRF to render high-resolution virtual views fast and output high-resolution 3D images. Among them, a coarse-to-fine 3D voxel rendering method is proposed to improve the accuracy of voxel representation effectively. Furthermore, a 3D voxel-based off-axis pixel encoding method is proposed to speed up 3D image generation. Finally, a sparse views dataset is built by ourselves to analyze the effectiveness of the proposed method. Experimental results demonstrate the method's effectiveness, which can fast synthesize novel views and 3D images with high resolution in real 3D scenes and physical simulation environments. PSNR of the virtual view is about 29.75 dB, SSIM is about 0.88, and the synthetic 8K 3D image time is about 14.41s. We believe that our fast high-resolution virtual viewpoint synthesis method can effectively improve the application of 3D light field display.