Light field 3D display technology is considered a revolutionary technology to address the critical visual fatigue issues in the existing 3D displays.Tabletop light field 3D display provides a brand-new display form th...Light field 3D display technology is considered a revolutionary technology to address the critical visual fatigue issues in the existing 3D displays.Tabletop light field 3D display provides a brand-new display form that satisfies multi-user shared viewing and collaborative works,and it is poised to become a potential alternative to the traditional wall and portable display forms.However,a large radial viewing angle and correct radial perspective and parallax are still out of reach for most current tabletop light field 3D displays due to the limited amount of spatial information.To address the viewing angle and perspective issues,a novel integral imaging-based tabletop light field 3D display with a simple flat-panel structure is proposed and developed by applying a compound lens array,two spliced 8K liquid crystal display panels,and a light shaping diffuser screen.The compound lens array is designed to be composed of multiple three-piece compound lens units by employing a reverse design scheme,which greatly extends the radial viewing angle in the case of a limited amount of spatial information and balances other important 3D display parameters.The proposed display has a radial viewing angle of 68.7°in a large display size of 43.5 inches,which is larger than the conventional tabletop light field 3D displays.The radial perspective and parallax are correct,and high-resolution 3D images can be reproduced in large radial viewing positions.We envision that this proposed display opens up possibility for redefining the display forms of consumer electronics.展开更多
We experimentally study the dynamic characteristics of a miniaturized spin-exchange relaxation-free(SERF) magnetometer based on uniform light field. The ceramic ferrule is used to expand the Gaussian beam to improve l...We experimentally study the dynamic characteristics of a miniaturized spin-exchange relaxation-free(SERF) magnetometer based on uniform light field. The ceramic ferrule is used to expand the Gaussian beam to improve light intensity uniformity, while the volume of the sensor is also reduced. This scheme makes the magnetometer have better sensitivity when the detected light intensity is less than 3.16 m W/cm^(2) at 120℃. When the temperature rises to 150℃ the sensitivity under the action of uniform light field is 18.5 f T/Hz^(1/2). The bandwidth of the sensor remains at the original level and meets application needs. The proposed structure improves transverse polarization uniformity within the miniaturized sensor, which is ideal for the magnetoencephalography and magnetocardiography imaging systems.展开更多
Single-cell volumetric imaging is essential for researching individual characteristics of cells.As a nonscanning imaging technique,lighteld microscopy(LFM)is a critical tool to achieve realtime three-dimensional imagi...Single-cell volumetric imaging is essential for researching individual characteristics of cells.As a nonscanning imaging technique,lighteld microscopy(LFM)is a critical tool to achieve realtime three-dimensional imaging with the advantage of single-shot.To address the inherent limits including nonuniform resolution and block-wise artifacts,various modied LFM strategies have been developed to provide new insights into the structural and functional information of cells.This review will introduce the principle and development of LFM,discuss the improved approaches based on hardware designs and 3D reconstruction algorithms,and present the applications in single-cell imaging.展开更多
Light field microscopy(LFM),featured for high threedimensional imaging speed and low pho-totoxicity,has emeged as a technique of choice for instantaneous volumetric inaging.In contrast with other scanning-based three ...Light field microscopy(LFM),featured for high threedimensional imaging speed and low pho-totoxicity,has emeged as a technique of choice for instantaneous volumetric inaging.In contrast with other scanning-based three dimensional(3D)imaging approaches,LFM enables to encode 3D spatial information in a snapshot manner,permitting high-speed 3D imaging that is only limited by the frame rate of the camera.In this review,we first introduce the fundamental theory of LFM and current corresponding advanced approaches.Then,we summarize various applica-tions of LFM in biological imaging.展开更多
In this paper, artificial intelligence image recognition technology is used to improve the recognition rate of individual domestic fish and reduce the recognition time, aiming at the problem that it is difficult to ea...In this paper, artificial intelligence image recognition technology is used to improve the recognition rate of individual domestic fish and reduce the recognition time, aiming at the problem that it is difficult to easily observe the species and growth of domestic fish in the underwater non-uniform light field environment. First, starting from the image data collected by polarizing imaging technology, this paper uses subpixel convolution reconstruction to enhance the image, uses image translation and fill technology to build the family fish database, builds the Adam-Dropout-CNN (A-D-CNN) network model, and its convolution kernel size is 3 × 3. The maximum pooling was used for downsampling, and the discarding operation was added after the full connection layer to avoid the phenomenon of network overfitting. The adaptive motion estimation algorithm was used to solve the gradient sparse problem. The experiment shows that the recognition rate of A-D-CNN is 96.97% when the model is trained under the domestic fish image database, which solves the problem of low recognition rate and slow recognition speed of domestic fish in non-uniform light field.展开更多
In the study of Terrestrial Gamma-ray Flashes (TGFs) and Sonoluminescence, we observe parallels with larger cosmic events. Specifically, sonoluminescence involves the rapid collapse of bubbles, which closely resembles...In the study of Terrestrial Gamma-ray Flashes (TGFs) and Sonoluminescence, we observe parallels with larger cosmic events. Specifically, sonoluminescence involves the rapid collapse of bubbles, which closely resembles gravitational collapse in space. This observation suggests the potential formation of low-density quantum black holes. These entities, which might be related to dark matter, are thought to experience a kind of transient evaporation similar to Hawking radiation seen in cosmic black holes. Consequently, sonoluminescence could be a valuable tool for investigating phenomena typically linked to cosmic scale events. Furthermore, the role of the Higgs boson is considered in this context, possibly connecting it to both TGFs and sonoluminescence. This research could enhance our understanding of the quantum mechanics of black holes and their relation to dark matter on Earth.展开更多
Light field imaging technology can obtain three-dimensional(3D)information of a test surface in a single exposure.Traditional light field reconstruction algorithms not only take a long time to trace back to the origin...Light field imaging technology can obtain three-dimensional(3D)information of a test surface in a single exposure.Traditional light field reconstruction algorithms not only take a long time to trace back to the original image,but also require the exact parameters of the light field system,such as the position and posture of a microlens array(MLA),which will cause errors in the reconstructed image if these parameters cannot be precisely obtained.This paper proposes a reconstruction algorithm for light field imaging based on the point spread function(PSF),which does not require prior knowledge of the system.The accurate PSF derivation process of a light field system is presented,and modeling and simulation were conducted to obtain the relationship between the spatial distribution characteristics and the PSF of the light field system.A morphology-based method is proposed to analyze the overlapping area of the subimages of light field images to identify the accurate spatial location of the MLA used in the system,which is thereafter used to accurately refocus light field imaging.A light field system is built to verify the algorithm’s effectiveness.Experimental results show that the measurement accuracy is increased over 41.0%compared with the traditional method by measuring a step standard.The accuracy of parameters is also improved through a microstructure measurement with a peak-to-valley value of 25.4%and root mean square value of 23.5%improvement.This further validates that the algorithm can effectively improve the refocusing efficiency and the accuracy of the light field imaging results with the superiority of refocusing light field imaging without prior knowledge of the system.The proposed method provides a new solution for fast and accurate 3D measurement based on a light field.展开更多
It is essential to investigate the light field camera parameters for the accurate flame temperature measurement because the sampling characteristics of the flame radiation can be varied with them. In this study, novel...It is essential to investigate the light field camera parameters for the accurate flame temperature measurement because the sampling characteristics of the flame radiation can be varied with them. In this study, novel indices of the light field camera were proposed to investigate the directional and spatial sampling characteristics of the flame radiation. Effects of light field camera parameters such as focal length and magnification of the main lens, focal length and magnification of the microlens were investigated. It was observed that the sampling characteristics of the flame are varied with the different parameters of the light field camera. The optimized parameters of the light field camera were then proposed for the flame radiation sampling. The larger sampling angle(23 times larger) is achieved by the optimized parameters compared to the commercial light field camera parameters. A non-negative least square(NNLS) algorithm was used to reconstruct the flame temperature. The reconstruction accuracy was also evaluated by the optimized parameters. The results suggested that the optimized parameters can provide higher reconstruction accuracy for axisymmetric and non-symmetric flame conditions in comparison to the commercial light field camera.展开更多
森林的实时渲染及光照是视景系统中的一个难题.基于图像的渲染方法(IBR)由于渲染速度与模型复杂度无关,被广泛应用于场景重建.基于光流场(Light Field Rendering)的IBR技术,提出一种迭代投射算法来进行外形重建,实现了具有实时光影特征...森林的实时渲染及光照是视景系统中的一个难题.基于图像的渲染方法(IBR)由于渲染速度与模型复杂度无关,被广泛应用于场景重建.基于光流场(Light Field Rendering)的IBR技术,提出一种迭代投射算法来进行外形重建,实现了具有实时光影特征的森林效果.实验表明该算法结合了传统迭代、投射算法各自的优点,在质量和效率方面取得了平衡.展开更多
The backscattering signal, which arises from the pulsed laser traveling through water, has limited the lidar system sensitivity and underwater target contrast. The transmitted optical carrier is modulated to be ultras...The backscattering signal, which arises from the pulsed laser traveling through water, has limited the lidar system sensitivity and underwater target contrast. The transmitted optical carrier is modulated to be ultrashort pulsed laser and it is effective to suppress the backscattering to adopt the coherent detection technology by identifying the modulation envelope. A nonstationary light field is formed in seawater by the ultrashort pulsed laser. The inherent relationship between the nonstationary light field formed by modulated lidar and the stationary light field formed by conventional lidar was discussed and the backscattering light model of the stationary light field for the ultrashort pulsed laser was proposed. The backscattering signal in modulated lidar system was processed and analyzed in the frequency domain on the basis of the model.展开更多
Light fields are vector functions that map the geometry of light rays to the corresponding plenoptic attributes.They describe the holographic information of scenes by representing the amount of light flowing in every ...Light fields are vector functions that map the geometry of light rays to the corresponding plenoptic attributes.They describe the holographic information of scenes by representing the amount of light flowing in every direction through every point in space.The physical concept of light fields was first proposed in 1936,and light fields are becoming increasingly important in the field of computer graphics,especially with the fast growth of computing capacity as well as network bandwidth.In this article,light field imaging is reviewed from the following aspects with an emphasis on the achievements of the past five years:(1)depth estimation,(2)content editing,(3)image quality,(4)scene reconstruction and view synthesis,and(5)industrial products because the technologies of lights fields also intersect with industrial applications.State-of-the-art research has focused on light field acquisition,manipulation,and display.In addition,the research has extended from the laboratory to industry.According to these achievements and challenges,in the near future,the applications of light fields could offer more portability,accessibility,compatibility,and ability to visualize the world.展开更多
The formation of the retroreflected light field is introduced in the paper and the components of the retroreflected light field are analyzed.Furthermore,a deep analysis of the factors affecting energy distribution of ...The formation of the retroreflected light field is introduced in the paper and the components of the retroreflected light field are analyzed.Furthermore,a deep analysis of the factors affecting energy distribution of the retroreflected light,such as design deviation,angle of incidence,was made.The simulation of the retroreflected light field was done.Recommendation is made in detail on both the energy distribution of the retroreflected light field at different working distances and the energy distribution of the retroreflected light field at a short distance when the diverging light comes.At last,two kinds of measuring instrument for the retroreflector are introduced,one is the long tunnel measuring instrument,the other is the minitype measuring instrument based on the character of the retroreflector when the diverging light comes.展开更多
A lateral current regulator diode (CRD) with field plates is proposed and experimentally demonstrated. The proposed CFtD is based on the junction field-effect transistor (JFET) structure. A cathode field plate is ...A lateral current regulator diode (CRD) with field plates is proposed and experimentally demonstrated. The proposed CFtD is based on the junction field-effect transistor (JFET) structure. A cathode field plate is adopted to alleviate the channel-length modulation effect and to improve the saturated I-V characteristics. An anode field plate is induced to achieve a high breakdown voltage VB of the CRD. The influence of the key device parameters on the I-V characteristics of the lateral CRD are discussed. Experimental results show that the proposed CRD presents good I-V characteristics with a high VB about 180 V and a low knee voltage (Vk) below 3 V. Furthermore, the proposed CRD has a negative temperature coefficient. The well characteristic of the proposed CRD makes it a cost-effective solution for light-emitting-diode lighting.展开更多
A light field modulated imaging spectrometer (LFMIS) can acquire the spatial-spectral datacube of targets of interest or a scene in a single shot. The spectral information of a point target is imaged on the pixels c...A light field modulated imaging spectrometer (LFMIS) can acquire the spatial-spectral datacube of targets of interest or a scene in a single shot. The spectral information of a point target is imaged on the pixels covered by a microlens. The pixels receive spectral information from different spectral filters to the diffraction and misalignments of the optical components. In this paper, we present a linear spectral multiplexing model of the acquired target spectrum. A calibration method is proposed for calibrating the center wavelengths and bandwidths of channels of an LFMIS system based on the liner-variable filter (LVF) and for determining the spectral multiplexing matrix. In order to improve the accuracy of the restored spectral data, we introduce a reconstruction algorithm based on the total least square (TLS) approach. Simulation and experimental results confirm the performance of the spectrum reconstruction algorithm and validate the feasibility of the proposed calibrating scheme.展开更多
A new approach for studying the time-evolution law of a chaotic light field in a damping-gaining coexisting process is presented. The new differential equation for determining the parameter of the density operator p(...A new approach for studying the time-evolution law of a chaotic light field in a damping-gaining coexisting process is presented. The new differential equation for determining the parameter of the density operator p(t) is derived and the solution of f for the damping and gaining processes are studied separately. Our approach is direct and the result is concise since it is not necessary for us to know the Kraus operators in advance.展开更多
We explore the time evolution law of a two-mode squeezed light field(pure state)passing through twin diffusion channels,and we find that the final state is a squeezed chaotic light field(mixed state)with entanglement,...We explore the time evolution law of a two-mode squeezed light field(pure state)passing through twin diffusion channels,and we find that the final state is a squeezed chaotic light field(mixed state)with entanglement,which shows that even though the two channels are independent of each other,since the two modes of the initial state are entangled with each other,the final state remains entangled.Nevertheless,although the squeezing(entanglement)between the two modes is weakened after the diffusion,it is not completely removed.We also highlight the law of photon number evolution.In the calculation process used in this paper,we make full use of the summation method within the ordered product of operators and the generating function formula for two-variable Hermite polynomials.展开更多
Image-Based Rendering (IBR) is one powerful approach for generating virtual views. It can provide convincing animations without an explicit geometric representation. In this paper, several implementations of light f...Image-Based Rendering (IBR) is one powerful approach for generating virtual views. It can provide convincing animations without an explicit geometric representation. In this paper, several implementations of light field rendering are summa- rized from prior arts. Several characteristics, such as the regu- lar pattern in Epipolar Plane Images (EPIs), of light field are explored with detail under 1D parallel camera arrangement. It is proved that it is quite efficient to synthesize virtual views for Super Multi-View (SMV) application, which is in the third phase of Free- Viewpoint Television (FTV). In comparison with convolutional stereo matching method, in which the inter- mediate view is synthesized by the two adjacent views, light field rendering makes use of more views supplied to get the high-quality views.展开更多
Based on the new finding of Wenchang L low-resistivity light oil field, the finding process, reservoir charac- teristics and pool-forming pattern were studied. The oil-rock correlation, neritic reservoir type, hydroca...Based on the new finding of Wenchang L low-resistivity light oil field, the finding process, reservoir charac- teristics and pool-forming pattern were studied. The oil-rock correlation, neritic reservoir type, hydrocarbon conduct system and dominant migration and accumulation direction, and new techniques were discussed. The results showed that large amount of hydrocarbon generated by shallow lacustrine mudstone and shale of Eocene Wenchang formation could migrate from sag to Qionghai uplift distantly; neritic shoal-bar reservoir have developed in the 1 st member of Zhujiang formation, dip-sag faults and regional good marine sandstone layers of the 1 st and the 2nd member of Zhujiang formation have constituted hydrocarbon conduct system in Qionghai uplift ; the late fault system which were controlled by Dongsha tectonic movement constructed the connection between lower hydrocarbon and upper neritic shoal-bar reservoir. There- fore, the pool-forming pattern with "vertical migration and accumulation, secondary strncture-lithology-dominated" was proposed. Finally the enlightenment of exploratin~ new findings was discussed.展开更多
Light field cameras have a wide area of applications, such as digital refocusing, scene depth information extraction and 3-D image reconstruction. By recording the energy and direction information of light field, they...Light field cameras have a wide area of applications, such as digital refocusing, scene depth information extraction and 3-D image reconstruction. By recording the energy and direction information of light field, they can well solve many technical problems that cannot be done by conventional cameras. An important feature of light field cameras is that a microlens array is inserted between the sensor and main lens, through which a series of sub-aperture images of different perspectives are formed. Based on this feature and the full-focus image acquisition technique, we propose a light-field optical flow calculation algorithm, which involves both the depth estimation and the occlusion detection and guarantees the edge-preserving property. This algorithm consists of three steps: 1) Computing the dense optical flow field among a group of sub-aperture images;2) Obtaining a robust depth-estimation by initializing the light-filed optical flow using the linear regression approach and detecting occluded areas using the consistency;3) Computing an improved light-field depth map by using the edge-preserving algorithm to realize interpolation optimization. The reliability and high accuracy of the proposed approach is validated by experimental results.展开更多
The number of good quality paleomagnetic data of the Mesoproterozoic supercontinent Nuna(e.g.Columbia,Hudsonland)has increased in recent years enabling more reliable global continental reconstructions(e.g Hoffman
基金We are grateful for financial supports from National Key R&D Program of China(Grant No.2021YFB2802300)the National Natural Science Foundation of China(Grant Nos.62105014,62105016,and 62020106010)。
文摘Light field 3D display technology is considered a revolutionary technology to address the critical visual fatigue issues in the existing 3D displays.Tabletop light field 3D display provides a brand-new display form that satisfies multi-user shared viewing and collaborative works,and it is poised to become a potential alternative to the traditional wall and portable display forms.However,a large radial viewing angle and correct radial perspective and parallax are still out of reach for most current tabletop light field 3D displays due to the limited amount of spatial information.To address the viewing angle and perspective issues,a novel integral imaging-based tabletop light field 3D display with a simple flat-panel structure is proposed and developed by applying a compound lens array,two spliced 8K liquid crystal display panels,and a light shaping diffuser screen.The compound lens array is designed to be composed of multiple three-piece compound lens units by employing a reverse design scheme,which greatly extends the radial viewing angle in the case of a limited amount of spatial information and balances other important 3D display parameters.The proposed display has a radial viewing angle of 68.7°in a large display size of 43.5 inches,which is larger than the conventional tabletop light field 3D displays.The radial perspective and parallax are correct,and high-resolution 3D images can be reproduced in large radial viewing positions.We envision that this proposed display opens up possibility for redefining the display forms of consumer electronics.
基金the National Natural Science Foundation of China (Grant No. 62003020)。
文摘We experimentally study the dynamic characteristics of a miniaturized spin-exchange relaxation-free(SERF) magnetometer based on uniform light field. The ceramic ferrule is used to expand the Gaussian beam to improve light intensity uniformity, while the volume of the sensor is also reduced. This scheme makes the magnetometer have better sensitivity when the detected light intensity is less than 3.16 m W/cm^(2) at 120℃. When the temperature rises to 150℃ the sensitivity under the action of uniform light field is 18.5 f T/Hz^(1/2). The bandwidth of the sensor remains at the original level and meets application needs. The proposed structure improves transverse polarization uniformity within the miniaturized sensor, which is ideal for the magnetoencephalography and magnetocardiography imaging systems.
基金This paper was supported by Shenzhen Science and Technology Innovation grants(JCYJ20200109115633343,JCYJ20210324123610030).
文摘Single-cell volumetric imaging is essential for researching individual characteristics of cells.As a nonscanning imaging technique,lighteld microscopy(LFM)is a critical tool to achieve realtime three-dimensional imaging with the advantage of single-shot.To address the inherent limits including nonuniform resolution and block-wise artifacts,various modied LFM strategies have been developed to provide new insights into the structural and functional information of cells.This review will introduce the principle and development of LFM,discuss the improved approaches based on hardware designs and 3D reconstruction algorithms,and present the applications in single-cell imaging.
基金supports offered by the National Natural Science Foundation of China (T2225014,21874052,61860206009)the National Key Research and Development Program of China (2017YFA0700501).
文摘Light field microscopy(LFM),featured for high threedimensional imaging speed and low pho-totoxicity,has emeged as a technique of choice for instantaneous volumetric inaging.In contrast with other scanning-based three dimensional(3D)imaging approaches,LFM enables to encode 3D spatial information in a snapshot manner,permitting high-speed 3D imaging that is only limited by the frame rate of the camera.In this review,we first introduce the fundamental theory of LFM and current corresponding advanced approaches.Then,we summarize various applica-tions of LFM in biological imaging.
文摘In this paper, artificial intelligence image recognition technology is used to improve the recognition rate of individual domestic fish and reduce the recognition time, aiming at the problem that it is difficult to easily observe the species and growth of domestic fish in the underwater non-uniform light field environment. First, starting from the image data collected by polarizing imaging technology, this paper uses subpixel convolution reconstruction to enhance the image, uses image translation and fill technology to build the family fish database, builds the Adam-Dropout-CNN (A-D-CNN) network model, and its convolution kernel size is 3 × 3. The maximum pooling was used for downsampling, and the discarding operation was added after the full connection layer to avoid the phenomenon of network overfitting. The adaptive motion estimation algorithm was used to solve the gradient sparse problem. The experiment shows that the recognition rate of A-D-CNN is 96.97% when the model is trained under the domestic fish image database, which solves the problem of low recognition rate and slow recognition speed of domestic fish in non-uniform light field.
文摘In the study of Terrestrial Gamma-ray Flashes (TGFs) and Sonoluminescence, we observe parallels with larger cosmic events. Specifically, sonoluminescence involves the rapid collapse of bubbles, which closely resembles gravitational collapse in space. This observation suggests the potential formation of low-density quantum black holes. These entities, which might be related to dark matter, are thought to experience a kind of transient evaporation similar to Hawking radiation seen in cosmic black holes. Consequently, sonoluminescence could be a valuable tool for investigating phenomena typically linked to cosmic scale events. Furthermore, the role of the Higgs boson is considered in this context, possibly connecting it to both TGFs and sonoluminescence. This research could enhance our understanding of the quantum mechanics of black holes and their relation to dark matter on Earth.
基金This work was partially supported by the National Key R&D Program of China(No.2017YFA0701200)the National Nat-ural Science Foundation of China(Grant No.52075100)Shanghai Science and Technology Committee Innovation Grant(19ZR1404600).
文摘Light field imaging technology can obtain three-dimensional(3D)information of a test surface in a single exposure.Traditional light field reconstruction algorithms not only take a long time to trace back to the original image,but also require the exact parameters of the light field system,such as the position and posture of a microlens array(MLA),which will cause errors in the reconstructed image if these parameters cannot be precisely obtained.This paper proposes a reconstruction algorithm for light field imaging based on the point spread function(PSF),which does not require prior knowledge of the system.The accurate PSF derivation process of a light field system is presented,and modeling and simulation were conducted to obtain the relationship between the spatial distribution characteristics and the PSF of the light field system.A morphology-based method is proposed to analyze the overlapping area of the subimages of light field images to identify the accurate spatial location of the MLA used in the system,which is thereafter used to accurately refocus light field imaging.A light field system is built to verify the algorithm’s effectiveness.Experimental results show that the measurement accuracy is increased over 41.0%compared with the traditional method by measuring a step standard.The accuracy of parameters is also improved through a microstructure measurement with a peak-to-valley value of 25.4%and root mean square value of 23.5%improvement.This further validates that the algorithm can effectively improve the refocusing efficiency and the accuracy of the light field imaging results with the superiority of refocusing light field imaging without prior knowledge of the system.The proposed method provides a new solution for fast and accurate 3D measurement based on a light field.
基金supported by the National Natural Science Foundation of China(Grant Nos.51676044 and 51327803)the Social Development Project of Jiangsu Province,China(Grant No.BE20187053)+1 种基金the Postgraduate Research and Practice Innovation Program of Jiangsu Province,China(Grant No.KYCX170081)China Scholarship Council
文摘It is essential to investigate the light field camera parameters for the accurate flame temperature measurement because the sampling characteristics of the flame radiation can be varied with them. In this study, novel indices of the light field camera were proposed to investigate the directional and spatial sampling characteristics of the flame radiation. Effects of light field camera parameters such as focal length and magnification of the main lens, focal length and magnification of the microlens were investigated. It was observed that the sampling characteristics of the flame are varied with the different parameters of the light field camera. The optimized parameters of the light field camera were then proposed for the flame radiation sampling. The larger sampling angle(23 times larger) is achieved by the optimized parameters compared to the commercial light field camera parameters. A non-negative least square(NNLS) algorithm was used to reconstruct the flame temperature. The reconstruction accuracy was also evaluated by the optimized parameters. The results suggested that the optimized parameters can provide higher reconstruction accuracy for axisymmetric and non-symmetric flame conditions in comparison to the commercial light field camera.
文摘森林的实时渲染及光照是视景系统中的一个难题.基于图像的渲染方法(IBR)由于渲染速度与模型复杂度无关,被广泛应用于场景重建.基于光流场(Light Field Rendering)的IBR技术,提出一种迭代投射算法来进行外形重建,实现了具有实时光影特征的森林效果.实验表明该算法结合了传统迭代、投射算法各自的优点,在质量和效率方面取得了平衡.
文摘The backscattering signal, which arises from the pulsed laser traveling through water, has limited the lidar system sensitivity and underwater target contrast. The transmitted optical carrier is modulated to be ultrashort pulsed laser and it is effective to suppress the backscattering to adopt the coherent detection technology by identifying the modulation envelope. A nonstationary light field is formed in seawater by the ultrashort pulsed laser. The inherent relationship between the nonstationary light field formed by modulated lidar and the stationary light field formed by conventional lidar was discussed and the backscattering light model of the stationary light field for the ultrashort pulsed laser was proposed. The backscattering signal in modulated lidar system was processed and analyzed in the frequency domain on the basis of the model.
基金The last author was supported by the National Key R&D Program of China,No.2019YFB1405703.
文摘Light fields are vector functions that map the geometry of light rays to the corresponding plenoptic attributes.They describe the holographic information of scenes by representing the amount of light flowing in every direction through every point in space.The physical concept of light fields was first proposed in 1936,and light fields are becoming increasingly important in the field of computer graphics,especially with the fast growth of computing capacity as well as network bandwidth.In this article,light field imaging is reviewed from the following aspects with an emphasis on the achievements of the past five years:(1)depth estimation,(2)content editing,(3)image quality,(4)scene reconstruction and view synthesis,and(5)industrial products because the technologies of lights fields also intersect with industrial applications.State-of-the-art research has focused on light field acquisition,manipulation,and display.In addition,the research has extended from the laboratory to industry.According to these achievements and challenges,in the near future,the applications of light fields could offer more portability,accessibility,compatibility,and ability to visualize the world.
文摘The formation of the retroreflected light field is introduced in the paper and the components of the retroreflected light field are analyzed.Furthermore,a deep analysis of the factors affecting energy distribution of the retroreflected light,such as design deviation,angle of incidence,was made.The simulation of the retroreflected light field was done.Recommendation is made in detail on both the energy distribution of the retroreflected light field at different working distances and the energy distribution of the retroreflected light field at a short distance when the diverging light comes.At last,two kinds of measuring instrument for the retroreflector are introduced,one is the long tunnel measuring instrument,the other is the minitype measuring instrument based on the character of the retroreflector when the diverging light comes.
基金Supported by the National Natural Science Foundation of China under Grant No 61376080
文摘A lateral current regulator diode (CRD) with field plates is proposed and experimentally demonstrated. The proposed CFtD is based on the junction field-effect transistor (JFET) structure. A cathode field plate is adopted to alleviate the channel-length modulation effect and to improve the saturated I-V characteristics. An anode field plate is induced to achieve a high breakdown voltage VB of the CRD. The influence of the key device parameters on the I-V characteristics of the lateral CRD are discussed. Experimental results show that the proposed CRD presents good I-V characteristics with a high VB about 180 V and a low knee voltage (Vk) below 3 V. Furthermore, the proposed CRD has a negative temperature coefficient. The well characteristic of the proposed CRD makes it a cost-effective solution for light-emitting-diode lighting.
基金Project supported by the National Natural Science Foundation of China(Grant No.61307020)Beijing Natural Science Foundation(Grant No.4172038)the Qingdao Opto-electronic United Foundation,China
文摘A light field modulated imaging spectrometer (LFMIS) can acquire the spatial-spectral datacube of targets of interest or a scene in a single shot. The spectral information of a point target is imaged on the pixels covered by a microlens. The pixels receive spectral information from different spectral filters to the diffraction and misalignments of the optical components. In this paper, we present a linear spectral multiplexing model of the acquired target spectrum. A calibration method is proposed for calibrating the center wavelengths and bandwidths of channels of an LFMIS system based on the liner-variable filter (LVF) and for determining the spectral multiplexing matrix. In order to improve the accuracy of the restored spectral data, we introduce a reconstruction algorithm based on the total least square (TLS) approach. Simulation and experimental results confirm the performance of the spectrum reconstruction algorithm and validate the feasibility of the proposed calibrating scheme.
基金Project supported by the National Natural Science Foundation of China (Grant Nos. 61141007,11047133,and 11175113)the Natural Science Foundation of Jiangxi Province of China (Grant Nos. 2010GQS0080 and 2010GQW0027)+1 种基金the Research Foundation of the Education Department of Jiangxi Province of China (Grant No. GJJ11339)the Sponsored Program for Cultivating Youths of Outstanding Ability in Jiangxi Normal University
文摘A new approach for studying the time-evolution law of a chaotic light field in a damping-gaining coexisting process is presented. The new differential equation for determining the parameter of the density operator p(t) is derived and the solution of f for the damping and gaining processes are studied separately. Our approach is direct and the result is concise since it is not necessary for us to know the Kraus operators in advance.
基金supported by the National Natural Science Foundation of China(Grant No.11775208)the Foundation for Young Talents in College of Anhui Province,China(Grant No.gxyq2019077)the Natural Science Foundation of the Anhui Higher Education Institutions of China(Grant Nos.KJ2019A0688 and KJ2020A0638)。
文摘We explore the time evolution law of a two-mode squeezed light field(pure state)passing through twin diffusion channels,and we find that the final state is a squeezed chaotic light field(mixed state)with entanglement,which shows that even though the two channels are independent of each other,since the two modes of the initial state are entangled with each other,the final state remains entangled.Nevertheless,although the squeezing(entanglement)between the two modes is weakened after the diffusion,it is not completely removed.We also highlight the law of photon number evolution.In the calculation process used in this paper,we make full use of the summation method within the ordered product of operators and the generating function formula for two-variable Hermite polynomials.
文摘Image-Based Rendering (IBR) is one powerful approach for generating virtual views. It can provide convincing animations without an explicit geometric representation. In this paper, several implementations of light field rendering are summa- rized from prior arts. Several characteristics, such as the regu- lar pattern in Epipolar Plane Images (EPIs), of light field are explored with detail under 1D parallel camera arrangement. It is proved that it is quite efficient to synthesize virtual views for Super Multi-View (SMV) application, which is in the third phase of Free- Viewpoint Television (FTV). In comparison with convolutional stereo matching method, in which the inter- mediate view is synthesized by the two adjacent views, light field rendering makes use of more views supplied to get the high-quality views.
文摘Based on the new finding of Wenchang L low-resistivity light oil field, the finding process, reservoir charac- teristics and pool-forming pattern were studied. The oil-rock correlation, neritic reservoir type, hydrocarbon conduct system and dominant migration and accumulation direction, and new techniques were discussed. The results showed that large amount of hydrocarbon generated by shallow lacustrine mudstone and shale of Eocene Wenchang formation could migrate from sag to Qionghai uplift distantly; neritic shoal-bar reservoir have developed in the 1 st member of Zhujiang formation, dip-sag faults and regional good marine sandstone layers of the 1 st and the 2nd member of Zhujiang formation have constituted hydrocarbon conduct system in Qionghai uplift ; the late fault system which were controlled by Dongsha tectonic movement constructed the connection between lower hydrocarbon and upper neritic shoal-bar reservoir. There- fore, the pool-forming pattern with "vertical migration and accumulation, secondary strncture-lithology-dominated" was proposed. Finally the enlightenment of exploratin~ new findings was discussed.
文摘Light field cameras have a wide area of applications, such as digital refocusing, scene depth information extraction and 3-D image reconstruction. By recording the energy and direction information of light field, they can well solve many technical problems that cannot be done by conventional cameras. An important feature of light field cameras is that a microlens array is inserted between the sensor and main lens, through which a series of sub-aperture images of different perspectives are formed. Based on this feature and the full-focus image acquisition technique, we propose a light-field optical flow calculation algorithm, which involves both the depth estimation and the occlusion detection and guarantees the edge-preserving property. This algorithm consists of three steps: 1) Computing the dense optical flow field among a group of sub-aperture images;2) Obtaining a robust depth-estimation by initializing the light-filed optical flow using the linear regression approach and detecting occluded areas using the consistency;3) Computing an improved light-field depth map by using the edge-preserving algorithm to realize interpolation optimization. The reliability and high accuracy of the proposed approach is validated by experimental results.
文摘The number of good quality paleomagnetic data of the Mesoproterozoic supercontinent Nuna(e.g.Columbia,Hudsonland)has increased in recent years enabling more reliable global continental reconstructions(e.g Hoffman