2022

• Record 133 of
  
  Title:High Dynamic Range Image Fusion Algorithm Based on Local Weighted Superposition
  
  Author(s):Guo, Lulu(1,2); Yi, Hongwei(1)
  Source: Guangzi Xuebao/Acta Photonica Sinica  Volume: 51  Issue: 11  DOI: 10.3788/gzxb20225111.1110001  Published: November 2022  
  Abstract:Aiming at the limitation of the dynamic range of the imaging sensor， the size of the local window and the fusion image method is further studied， and the multi-exposure image fusion method based on the camera response curve is improved. By changing the exposure time， a set of images with different exposure degrees is obtained， and image fusion is performed on the high-brightness image and the low-brightness image. Firstly， the conversion factor is directly calculated based on the image pixel value， which simplifies the calculation of the pixel ratio factor curve of the High Exposure （HE） image and Low Exposure （LE） image， and avoids the solution of the camera response curve. The pixel values in the low-brightness image are mapped to the pixel value range of the high-brightness image through the ratio factor， and then the image is subjected to local windowing processing. There are three cases of overexposure and good overexposure. For different exposure situations， according to the saturation of the neighborhood pixels in the highlighted image window， different weight coefficients are determined for multi-exposure weighted fusion， which is roughly divided into three steps： 1） Select the unsaturated pixel value of the HE image and the corresponding pixel value in the LE image to linearly fit to obtain the pixel ratio factor curve. 2） After adding local windows to the HE image， determine the saturation of the pixel values in each window. Whether the center pixel value of the highlighted image is saturated and whether the neighborhood pixel values of the center value are all saturated， the exposure of the center pixel value is determined. The situations are divided into three categories， 1） Good exposure： the central pixel value is not saturated， and all the neighborhood pixel value sets are not saturated； 2） Incomplete overexposure： the central pixel value is not saturated， the neighborhood pixel value set is not completely saturated or the central pixel When the value is saturated， at least one of the neighboring pixel value sets is saturated； 3） Complete overexposure： the center pixel value is saturated， and the neighborhood pixel value set is also saturated. 3） According to the saturation situation， determine the weight coefficient of each pixel value fusion of the HE and the LE images. The weight coefficient is determined by the proportion of unsaturated pixel values in the neighborhood pixel value set in the HE image， and the final HDR image is obtained by weighted fusion. In terms of experimental verification， two typical multi-exposure fusion test sets of Bottle and Airport are selected to select the size of the local window and the imaging effect in a low signal-to-noise ratio environment. The wavelet transform fusion method and the window fusion method in this paper are compared horizontally. The experimental results show that：（1） With the increase of the selected window， the more pixels involved in the calculation， the influence of the over-bright central pixel value in the scene in the fusion process gradually decreases， the overall brightness decreases， and the quality of the fused image is more vulnerable. However， if the selection window is too small， the estimation accuracy of the saturated pixel value of the neighboring pixels will decrease. Therefore， in the selection of the window size， the influence of local noise on the quality of the fused image and the constraining ability of the neighboring pixels to the highlighted center pixel value should be considered at the same time. In order to achieve a better fusion effect， the algorithm in this paper selects the 5 × 5 window to fuse multiple images， improves the contrast of the image while maintaining the details of the image， and effectively restores the changes in the light and dark levels in the scene. （2） When the image signal-to-noise ratio is higher than 18 dB， the dark scene information in the LE image can still be effectively recovered after fusion， and the overall imaging effect of the fusion result can be guaranteed. There are two main reasons for the improvement of the anti-noise ability of the fused image： 1） The algorithm tries to use the pixel value in the highlighted image as much as possible， but the signal value of the highlighted image is generally too large， and the SNR of the pixel value after adding noise is still very large. 2） The pixel value of the low-brightness image used to replace the overexposed pixel value of the high-brightness image will also be larger， so the influence of noise on the pixel value will also be reduced. （3） Compared with other algorithms， the algorithm in this paper can not only keep the overall contrast accurate and the image undistorted but also restore the edge clarity， retain the dark information in the bright environment， and reduce the halo caused by the strong light source. At the same time， the fusion algorithm uses local windows to process pixel values. The calculations between each window are independent of each other， and it is not necessary to process pixel values with good exposure. Therefore， the unique values of independent operations between each window are expected to be realized on hardware platforms such as GPU. Thread parallel processing， with the potential to achieve HDR real-time fast imaging. © 2022 Chinese Optical Society. All rights reserved.
  Accession Number: 20224513074607
• Record 134 of
  
  Title:Hyperspectral Unmixing Using Nonlocal Similarity-Regularized Low-Rank Tensor Factorization
  
  Author(s):Yuan, Yuan(1); Dong, Le(2,3); Li, Xuelong(1)
  Source: IEEE Transactions on Geoscience and Remote Sensing  Volume: 60  Issue:   DOI: 10.1109/TGRS.2021.3095488  Published: 2022  
  Abstract:Recently, methods based on nonnegative tensor factorization (NTF), which benefits from the tensor representation of hyperspectral imagery (HSI) without any information loss, have attracted increasing attention. However, most existing methods fail to explore the internal spatial structure of data, resulting in low unmixing performance. Moreover, when the algorithm is optimized, the solution is unstable. In this article, a regularizer based on nonlocal tensor similarity is proposed, which can not only fully preserve the global information of HSI but also mine the internal information of data in the spatial domain. HSI is regarded as a 3-D tensor and is directly subjected to endmember extraction and abundance estimation. To fully explore the structural characteristics of data, we simultaneously use the local smoothing and low tensor rank prior of the data to constrain the unmixing model. First, several 4-D tensor groups can be obtained after the nonlocal similarity structure of HSI is learned. Subsequently, a low tensor rank prior is applied to each 4-D tensor, which can fully simulate the nonlocal similarity in the image. In addition, total variation (TV) is also used to explore the local spatial relationship of data, which can generate a smooth abundance map through edge preservation. The optimization is solved by the ADMM algorithm. Experiments on synthetic and real data illustrate the superiority of the proposed method. © 1980-2012 IEEE.
  Accession Number: 20220511562886
• Record 135 of
  
  Title:Research on Valuation Level Analysis and Prediction Method of Listed Enterprises Based on Market Sales Ratio
  
  Author(s):Wen, Xingjian(1); Chen, Yaxuan(2); Yang, Kai(3); Wang, Fan(3,4,5); Li, Xijie(6)
  Source: ACM International Conference Proceeding Series  Volume:   Issue:   DOI: 10.1145/3531028.3531031  Published: March 25, 2022  
  Abstract:Enterprise valuation is the evaluation of an enterprise's value, which is the focus of research in the financial field. In recent years, with the establishment of China's science and innovation board stock market, enterprise valuation has once again become a hot research topic. Accurate enterprise valuation model has important economic significance for enterprise listing and securities investment. However, the existing valuation methods mainly evaluate the enterprise value through the accounting of some economic indicators. The index information designed in this kind of method is difficult to obtain and is not suitable for investors. How to use the fundamental data and liquidity index data of enterprises to accurately predict the market sales rate plays an important role. Firstly, through the multiple linear regression model, this paper analyzes the prediction of market sales rate, analyzes and summarizes the problems existing in the multiple linear regression model. Secondly, through nonlinear transformation and time series index, an effective market sales rate prediction model is established. Finally, through the prediction and analysis of listed enterprises in China's A-share market, the goodness of the model is successfully improved, which fully verifies the effectiveness of our proposed method. © 2022 ACM.
  Accession Number: 20223012397908
• Record 136 of
  
  Title:A Data Mining Algorithm for Hyperspectral Target Detection Based on UAV
  
  Author(s):Zhou, Jian(1); Qiu, Shi(2); Wang, Zhuping(3); Nie, Cong(1)
  Source: Lecture Notes in Electrical Engineering  Volume: 861 LNEE  Issue:   DOI: 10.1007/978-981-16-9492-9_7  Published: 2022  
  Abstract:The hyperspectral image has spatial resolution and inter-spectral resolution, which can visually display the information of the ground object. It is of great significance to the typical targets of hyperspectral data mining. With the development of drone technology, it is possible to detect targets with airborne hyper spectrometers, thereby greatly improving the perception ability of unmanned aerial vehicles. For this reason, we have carried out research on target data mining based on the advantages of hyperspectral detection of ground object attributes and the strong flexibility of UAVs. First, on the basis of acquiring hyper spectral images, normalize the images, construct an edge extraction model, and introduce the idea of clustering to find spatially similar regions. Then a Dynamic Time Warping model is constructed to extract the features between the spectra, and finally, the DEC algorithm is improved, and a deep network is used to achieve typical target clustering. © 2022, The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd.
  Accession Number: 20222212177677
• Record 137 of
  
  Title:An Integrated Solution of UAV Push-Broom Hyperspectral System Based on Geometric Correction with MSI and Radiation Correction Considering Outdoor Illumination Variation
  
  Author(s):Song, Liyao(1); Li, Haiwei(2); Chen, Tieqiao(2); Chen, Junyu(2); Liu, Song(2); Fan, Jiancun(1); Wang, Quan(2)
  Source: Remote Sensing  Volume: 14  Issue: 24  DOI: 10.3390/rs14246267  Published: December 2022  
  Abstract:The unmanned aerial vehicle (UAV)-borne hyperspectral imaging system has the advantages of high spatial resolution, flexible operation, under-cloud flying, and easy cooperation with ground synchronous tests. Because this platform often flies under clouds, variations in solar illumination lead to irradiance inconsistency between different rows of hyperspectral images (HSIs). This inconsistency causes errors in radiation correction. In addition, due to the accuracy limitations of the GPS/inertial measurement unit (IMU) and irregular changes in flight platform speed and attitude, HSIs have deformation and drift, which is harmful to the geometric correction and stitching accuracy between flight strips. Consequently, radiation and geometric error limit further applications of large-scale hyperspectral data. To address the above problems, we proposed an integrated solution to acquire and correct UAV-borne hyperspectral images that consist of illumination data acquisition, radiance and geometric correction, HSI, multispectral image (MSI) registration, and multi-strip stitching. We presented an improved three-parameter empirical model based on the illumination correction factor, and it showed that the accuracy of radiation correction considering illumination variation improved, especially in some low signal-to-noise ratio (SNR) bands. In addition, the error of large-scale HSI stitching was controlled within one pixel. © 2022 by the authors.
  Accession Number: 20225313323499
• Record 138 of
  
  Title:A New Method for Direct Measurement of Polarization Characteristics of Water-Leaving Radiation
  
  Author(s):Liu, Jia(1); Jia, Xinyin(1); He, Xianqiang(2); Wang, Yihao(1); Zhu, Qiankun(1); Li, Haiwei(1); Zou, Chunbo(1); Chen, Tieqiao(1); Feng, Xiangpeng(1); Zhang, Geng(1); Li, Siyuan(1); Hu, Bingliang(1); Pan, Delu(3)
  Source: IEEE Transactions on Geoscience and Remote Sensing  Volume: 60  Issue:   DOI: 10.1109/TGRS.2021.3126926  Published: 2022  
  Abstract:The polarization characteristics of water-leaving radiation, which contain rich information on oceanic constituents, have often been neglected. Due to the lack of suitable instruments and practical difficulties in removing strong contamination by polarized skylight, direct measurement of the polarization of water-leaving radiation remains a challenge. In this study, we designed an above-water instrument (named POLWR) to directly measure the polarization of water-leaving radiation and examined its field application in Qiandao Lake, China. Results showed that the Stokes components of water-leaving radiance ( L-{w} ) measured by POLWR were consistent with the radiative transfer (RT) simulations, with a determination coefficient ( R^{2} ) and mean relative error of 0.67 and 18.86%, respectively. The Qiandao Lake results revealed that the degree of polarization (DOP) of L-{w} varied from 0.05 to 0.5 within the 412-865-nm range. Moreover, a good relationship between the polarized remote sensing reflectance ( R-{\mathrm {rsp}} ), and DOP and chlorophyll-A (Chla) concentration was found at 368 nm in this productive lake, indicating great potential for the inversion of oceanic constituents from polarization signals. With its small size and direct measurement ability, the POLWR instrument should be widely applicable and could help improve our understanding of the polarization characteristics of water-leaving radiation and the underwater light field. © 1980-2012 IEEE.
  Accession Number: 20214611167785
• Record 139 of
  
  Title:Using Triple Collocation Observations to Estimate Satellite Measurement Noise
  
  Author(s):Chen, Jun(1); Quan, Wenting(2); Wang, Kexin(3); Han, Qijin(4); Liu, Jia(5); Xing, Qianguo(6); Xu, Na(7)
  Source: IEEE Transactions on Geoscience and Remote Sensing  Volume: 60  Issue:   DOI: 10.1109/TGRS.2021.3060781  Published: 2022  
  Abstract:Knowing how much measurement noise is in a signal is critical for evaluating the overall performance of a satellite observation. We developed a triple collocation observation (TCO) algorithm for estimating measurement noise by collocation comparing the local deviations of three satellite data sets. When we evaluated our algorithm with a synthetic data set, the results showed that the algorithm effectively derived measurement noise from satellite signals despite the many intermission signal differences among the satellites. The TCO algorithm produced © 1980-2012 IEEE.
  Accession Number: 20211310144189
• Record 140 of
  
  Title:Optical Design of the Transit Telescope for The Earth 2.0 Mission
  
  Author(s):Zhou, Dan(1); Zhang, Congcong(1); Ge, Jian(1); Zhang, Hui(1); Zhang, Yongshuai(1); Yu, Yong(1); Chen, Yonghe(2); Liu, Xiaohua(2); Song, Zongxi(3); Gao, Wei(3); Zhang, Hongfei(4); Wang, Jian(4)
  Source: Proceedings of SPIE - The International Society for Optical Engineering  Volume: 12180  Issue:   DOI: 10.1117/12.2630673  Published: 2022  
  Abstract:The Earth 2.0 (ET) mission is a Chinese next-generation space mission aiming at detecting thousands of terrestrial-like planets, including habitable Earth-like planets orbiting solar type stars (i.e., Earth's 2.0s), cold low-mass planets, and free-floating planets. The ET mission will use six 300 mm diameter wide field telescope arrays to continuously monitor 1.2 million FGKM dwarf stars in the original Kepler field and its adjacent regions for four consecutive years to search for new planets including Earth 2.0s using the transit technique. The six telescopes have the same configuration, point to the same sky area, and constitute the main scientific payload. Each telescope has an effective aperture of 300 mm with a very wide field of view (FOV) of 500 square degrees and a wavelength coverage of 450-900 nm. Each telescope is equipped with a focal plane mosaic camera. The mosaic camera is composed of 2×2, 9k×9k CMOS detectors with pixel size of 10µm. The optical design results in the diameter of the 90% encircled energy (EE90%) less than 40µm (or 4 pixels) over the entire FOV. About 20% vignetting at the edge of the FOV is introduced to provide good throughput for the entire FOV while keeping optics size and weight down to reduce manufacturing risk and scientific payload within the mass and volume limit. In this paper, we will present the optical design details, including influence analysis of various factors on image quality, e.g., glass material, detector flatness, manufacturing and assembly tolerances. In addition, we will describe temperature stability analysis of the telescope on image quality and photometry measurements. © 2022 SPIE.
  Accession Number: 20230413449800
• Record 141 of
  
  Title:Abnormal event detection by a weakly supervised temporal attention network
  
  Author(s):Zheng, Xiangtao(1); Zhang, Yichao(1,2); Zheng, Yunpeng(1,2); Luo, Fulin(3); Lu, Xiaoqiang(1)
  Source: CAAI Transactions on Intelligence Technology  Volume: 7  Issue: 3  DOI: 10.1049/cit2.12068  Published: September 2022  
  Abstract:Abnormal event detection aims to automatically identify unusual events that do not comply with expectation. Recently, many methods have been proposed to obtain the temporal locations of abnormal events under various determined thresholds. However, the specific categories of abnormal events are mostly neglect, which are important to help in monitoring agents to make decisions. In this study, a Temporal Attention Network (TANet) is proposed to capture both the specific categories and temporal locations of abnormal events in a weakly supervised manner. The TANet learns the anomaly score and specific category for each video segment with only video-level abnormal event labels. An event recognition module is exploited to predict the event scores for each video segment while a temporal attention module is proposed to learn a temporal attention value. Finally, to learn anomaly scores and specific categories, three constraints are considered: event category constraint, event separation constraint and temporal smoothness constraint. Experiments on the University of Central Florida Crime dataset demonstrate the effectiveness of the proposed method. © 2021 The Authors. CAAI Transactions on Intelligence Technology published by John Wiley & Sons Ltd on behalf of The Institution of Engineering and Technology and Chongqing University of Technology.
  Accession Number: 20214911260464
• Record 142 of
  
  Title:Conceptual Design Study of the Science Payload for the Earth 2.0 Mission
  
  Author(s):Chen, Yonghe(1); Yin, Dayi(1); Wei, Chuanxin(1); Liu, Xiaohua(1); Zhang, Quan(1); Yang, Baoyu(1); Zhu, Yuji(1); Ge, Jian(4); Zhou, Dan(2); Zhang, Congcong(2); Li, Yan(2); Song, Zongxi(3); Gao, Wei(3); Li, Wei(3); Wang, Fengtao(3); Shen, Chao(3); Pan, Yue(3); Zhang, Hongfei(4); Wang, Jian(4); Wang, Hui(4)
  Source: Proceedings of SPIE - The International Society for Optical Engineering  Volume: 12180  Issue:   DOI: 10.1117/12.2630044  Published: 2022  
  Abstract:The Earth 2.0 (ET) mission is a space mission in China which will be operated at the Earth-Sun L2 orbit with a designed lifetime longer than 4 years. ET's scientific payload consist of six 30cm diameter transit telescopes with each field of view of 500 square degrees and one 35 cm diameter microlensing telescope with a field of view of 4 square degrees. Each telescope is equipped with a camera with 2×2 9K×9K CMOS detectors, and Front-end Electronics (FEE). Each transit telescope is an f/1.57 eight-lens refractive optical system while the microlensing telescope is an f/17.2 catadioptric optical system with diffraction-limited design. The diameter of 90% Encircled Energy (EE90) for transit telescopes is within 5×5 pixels while the FWHM of PSF for the microlensing telescope is less than 0.78 arcsec. Fine Guidance Sensors are mounted at the four edges of the CMOS camera. All seven telescopes are fixed on a common mounting reference plate, and a large sun shield is used to block the heat flow from the Sun and provide a stable thermal environment for the telescopes. It also blocks straylight form the Sun, Earth, and the Moon. Each telescope has an additional top hood to block straylight incident at a large angle while the top hood is also used as a radiator to cool the detectors to below - 40℃. With PID heating loops, each telescope will work at -30±0.3℃ while the detectors work at - 40±0.1℃. Details of the conceptual design for the scientific payload will be presented. © 2022 SPIE.
  Accession Number: 20230413449646
• Record 143 of
  
  Title:On-Chip Temporal Coherence Synthesis for Classical and Quantum Waveform Processing
  
  Author(s):Chemnitz, Mario(1); Fischer, Bennet(1); MacLellan, Benjamin(1); Roztocki, Piotr(1); Helsten, Robin(1); Wetzel, Benjamin(2); Little, Brent E.(3); Chu, Sai T.(4); Moss, David J.(5); Azaña, José(1); Morandotti, Roberto(1)
  Source: Optics InfoBase Conference Papers  Volume:   Issue:   DOI:   Published: 2022  
  Abstract:We use a low-loss, user-friendly on-chip interferometer cascade to exploit the concept of temporal coherence synthesis for the shaping of optical pulses and, first-time, of the joint spectral intensity of broadband correlated photon pairs. © Optica Publishing Group 2022, © 2022 The Author(s)
  Accession Number: 20223512662554
• Record 144 of
  
  Title:Scalable, Autonomous On-Chip Picosecond Pulse-Shaping Enabled by Smart Optimization
  
  Author(s):Fischer, Bennet(1); Chemnitz, Mario(1); MacLellan, Benjamin(1); Roztocki, Piotr(1); Helsten, Robin(1); Wetzel, Benjamin(2); Little, Brent(3); Chu, Sai(4); Moss, David(5); Azaña, José(1); Morandotti, Roberto(1)
  Source: 2022 Conference on Lasers and Electro-Optics, CLEO 2022 - Proceedings  Volume:   Issue:   DOI:   Published: 2022  
  Abstract:We demonstrate a scalable, autonomous on-chip pulse shaping system based on temporal coherence synthesis. The inclusion of smart optimization algorithms enables robust, and reconfigurable pulse-shaping over a wide range of input and target durations. © Optica Publishing Group 2022, © 2022 The Author(s)
  Accession Number: 20224212986353