2021
2021
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Record 157 of
Title:Hierarchical Edge Refinement Network for Saliency Detection
Author(s):Song, Dawei(1); Dong, Yongsheng(2); Li, Xuelong(2)Source: IEEE Transactions on Image Processing Volume: 30 Issue: DOI: 10.1109/TIP.2021.3106798 Published: 2021Abstract:At present, most saliency detection methods are based on fully convolutional neural networks (FCNs). However, FCNs usually blur the edges of salient objects. Due to that, the multiple convolution and pooling operations of the FCNs will limit the spatial resolution of the feature maps. To alleviate this issue and obtain accurate edges, we propose a hierarchical edge refinement network (HERNet) for accurate saliency detection. In detail, the HERNet is mainly composed of a saliency prediction network and an edge preserving network. Firstly, the saliency prediction network is used to roughly detect the regions of salient objects and is based on a modified U-Net structure. Then, the edge preserving network is used to accurately detect the edges of salient objects, and this network is mainly composed of the atrous spatial pyramid pooling (ASPP) module. Different from the previous indiscriminate supervision strategy, we adopt a new one-to-one hierarchical supervision strategy to supervise the different outputs of the entire network. Experimental results on five traditional benchmark datasets demonstrate that the proposed HERNet performs well when compared with the state-of-the-art methods. ? 1992-2012 IEEE.Accession Number: 20213710897470 -
Record 158 of
Title:Design of a catadioptric system for infrared star sensor with wide field of view
Author(s):Yan, Haoyu(1); Wang, Hu(2); Xue, Yaoke(2); Ma, Zehua(1)Source: Proceedings of SPIE - The International Society for Optical Engineering Volume: 12069 Issue: DOI: 10.1117/12.2606881 Published: 2021Abstract:To achieve precise applications under specific environmental requirements, an infrared optical system that can be applied to near-infrared wavelengths was designed. First of all,based on the selected parameters 1/4-The initial structure was selected and the form of the Maxutov telescope was selected and improved.Then 1/4-The detection performance of the design results was analyzed.Due to the large range of high and low temperature changes in the outer space environment, the system lens barrel material analysis was carried out to obtain the influence of temperature changes on the energy distribution of the optical system.Finally 1/4-A tolerance analysis and optimization of the designed system were conducted so that it could meet the needs of processing and assembly.The design and analysis results indicate that the optical system adopts a spherical catadioptric mirror surface, the total length of the system is 126.218mm, the full field of view for a 14 μm surrounding energy distribution is > 80%, the maximum magnification chromatic aberration value of monochromatic light with a center wavelength of 1.3μm is ? COPYRIGHT SPIE. Downloading of the abstract is permitted for personal use only.Accession Number: 20220211444610 -
Record 159 of
Title:Research on geometric error correction of pushbroom hyperspectral camera carried by UAV
Author(s):Yihao, Wang(1,3); Qiang, Cong(2); Shun, Yao(2); Xinyin, Jia(1); Jianyu, Chen(3); Siyuan, Li(1)Source: Proceedings of SPIE - The International Society for Optical Engineering Volume: 11763 Issue: DOI: 10.1117/12.2586957 Published: 2021Abstract:In recent years, the commercialized low-cost rotor UAV equipped with small hyperspectral camera has become an emerging way to acquire hyperspectral remote sensing data due to its advantages of convenient data acquisition and low cost, and has been widely used in environmental monitoring, precision agriculture, ocean development and other fields. Due to its light weight, the flight process of the rotor UAV is vulnerable to the influence of air flow, which leads to the poor stability of the platform and resulting in the geometric distortion of the imaging. This situation is particularly prominent in the obvious air flow areas such as the lake and the sea, which restricts the application in related fields. In this paper, the geometric processing of UAV-borne hyperspectral measured data collected at a wharf in Qiandao Lake is studied. There are two major factors lead to geometric error. One is the longitude and latitude step error, the other is the frame frequency of the navigation data is lower than the image exposure frame frequency. In this situation, this paper proposes a step fitting method to perform geometric correction and error correction for the hyperspectral airstrip data. Compared with the traditional Kalman filtering method and the global linear fitting method, the proposed method can better correct the geometric distortion of hyperspectral image caused by the low-precision GPS/INS system, which provides a foundation for the subsequent quantitative application of lightweight UAV hyperspectral camera in various fields. ? 2021 SPIEAccession Number: 20211410162068 -
Record 160 of
Title:Optimization of resistive anode for a single photon imaging detector
Author(s):Yang, Kai(1,2); Wang, Bo(1); Bai, Yonglin(1); Cao, Weiwei(1); Yang, Yang(1); Zhu, Bingli(1); Zheng, Jinkun(1); Bai, Xiaohong(1)Source: Proceedings of SPIE - The International Society for Optical Engineering Volume: 12065 Issue: DOI: 10.1117/12.2606769 Published: 2021Abstract:A Finite Element Method (FEM) to establish the model of CAT resistive anode and Square resistive anode is proposed. The characteristics of electrode charge signal are analyzed. The factors that affect the position reconstruction linearity of resistive anode are analyzed, including the geometric parameters and sheet resistance of the surface resistive layer, by calculating the amount of electrode charge from a simulated photon hit. It has been concluded that signal development time should be greater than 8R'C' (R'C' =RC2) seconds in order to ensure the root mean square (RMS) nonlinearity (%) of position reconstruction is less than 3% for these two resistive anodes, with capacitance C, and sheet resistance R of sensitive region. ? 2021 SPIE.Accession Number: 20220211437954 -
Record 161 of
Title:Hyperspectral Anomaly Detection Based on 3D Convolutional Autoencoder and Low Rank Representation
Author(s):Sun, Bangyong(1,2); Zhao, Zhe(1); Hu, Bingliang(2); Yu, Tao(2)Source: Guangzi Xuebao/Acta Photonica Sinica Volume: 50 Issue: 4 DOI: 10.3788/gzxb20215004.0410003 Published: April 25, 2021Abstract:Due to the challenge of high dimensionality, insufficient utilization of spatial-spectral information and limited local structure property expression in hyperspectral images, a hyperspectral anomaly detection algorithm based on 3D convolutional autoencoder and low rank representation is proposed in this paper. Firstly, the spectral-spatial features of hyperspectral images are extracted by 3D convolutional autoencoder. In order to precisely represent the local similarity, a new loss function is proposed to constrain the central pixel and it's surrounding pixels to extract more discriminative features. And then, the Density Based Spatial Clustering of Applications with Noise (DBSCAN) algorithm is used to construct the background dictionary, and the abnormal region is separated by low rank representation on the feature map. Finally, the detection result is obtained by fusing the reconstruction error obtained by 3D convolution autoencoder and abnormal region detection result. We carry out objective and subjective anomaly detection experiments on two real hyperspectral datasets. The results demonstrate that the proposed algorithm detect abnormal targets more accurately compared with other algorithms. ? 2021, Science Press. All right reserved.Accession Number: 20212010359826 -
Record 162 of
Title:Small Moving Target Recognition in Star Image with TRM
Author(s):Du, Yun(1,2,3); Wen, Desheng(1); Liu, Guizhong(2); Qiu, Shi(1)Source: International Journal of Pattern Recognition and Artificial Intelligence Volume: 35 Issue: 2 DOI: 10.1142/S021800142150004X Published: February 2021Abstract:Recognition of small moving targets in space has become one of the frontier scientific researches in recent decade. Most of them focus on detection and recognition in star image with sidereal stare mode. However, in this research field, few researches are about detection and recognition in star image with track rate mode. In this paper, a novel approach is proposed to recognize the moving target in single frame by machine learning method based on elliptical characteristic extraction of star points. The technical path about recognition of moving target in space is redesigned instead of traditional processing approaches. Elliptical characteristics of each star point can be successfully extracted from single image. Machine learning can achieve the classification goal in order to make sure that all moving targets can be extracted. The experiments show that our proposed approach can have better performance in star images with different qualities. ? 2021 World Scientific Publishing Company.Accession Number: 20204509461729 -
Record 163 of
Title:Real-time fire detection network for intelligent surveillance systems
Author(s):Liu, Ruqi(1,2); Wu, Siyuan(1,2); Lu, Xiaoqiang(1)Source: Proceedings of SPIE - The International Society for Optical Engineering Volume: 11911 Issue: DOI: 10.1117/12.2604559 Published: 2021Abstract:Based on the concept of deep learning, the proposed convolutional neural networks (CNNs) processing of extracted image features has been recently applied to tackle early fire detection during surveillance. However, such methods generally need more computational time and memory and seldom take smoke that always produced before fires into consideration, which results in poor detection speed and accuracy relatively. In this paper, we propose a novel imagebased fire and smoke detection network. Inspired by Yolov5 architecture, considering the untargeted feature extraction capability and limited receptive fields of Yolov5, the SSHC (Single Stage Headless Context) module is added to the backbone layer to enhance the feature extraction of flames and smoke. The RFB (Receptive Field Block) module is added to the fusion layer to increase the receptive field of our network. Not only does our network detect fire and smoke well in different fire scenes, different shooting angles, and different lighting conditions, but also achieves a speed of 83 FPS, meeting the real-time detection requirements in the detection speed. Meanwhile, we have built a high quality, constructed by collecting from real scenes and annotated by strict and reasonable rules dataset for fire and smoke detection to verify the superiority of our network. Our proposed network achieves 97.2% accuracy for fire detection, 92.4% accuracy for smoke detection. Experimental results on benchmark fire-smoke datasets reveal the effectiveness of the proposed framework and validate its suitability for fire and smoke detection in surveillance systems compared to state-of-the-art methods. ? 2021 SPIE.Accession Number: 20214511113416 -
Record 164 of
Title:Zoom lens with large aperture and long focal length in the integration system of detection and recognition
Author(s):Yao, Rui(1,2); Li, Xuyang(1); Ma, Zixuan(1,2); Ren, Zhiguang(1,2); Chu, Nanqing(1,2)Source: Proceedings of SPIE - The International Society for Optical Engineering Volume: 12070 Issue: DOI: 10.1117/12.2604746 Published: 2021Abstract:This paper designs an integrated optical system for detection and recognition. The system combines the R-C (Ritchey-Chretien optics) system and the zoom structure. The R-C mirror design of the initial structure of the system is completed by calculation of theory. Then, use the zoom theory to complete the design of the two zoom positions. The two zoom positions respectively realize the detection and identification of space debris. The F numbers are 5.86 and 11. The field of view angles are 2.83°and 0.6°. It works in band of 400-750nm. The system has an entrance pupil diameter of 300mm. The detection position can detect space debris with a brightness of 13 magnitude stars, with focal length of 1760mm; the recognition position's modulation transfer function is greater than 0.6 at the Nyquist frequency of 33.33lp/mm, with the focal length of 3300mm. The zoom theory is well applied in the integrated detection and recognition system. ? 2021 SPIEAccession Number: 20220811682281 -
Record 165 of
Title:Frontiers in science and applications for attosecond light source
Author(s):Fu, Yuxi(1,2)Source: Kexue Tongbao/Chinese Science Bulletin Volume: 66 Issue: 8 DOI: Published: March 15, 2021Abstract:nullAccession Number: 20211310141478 -
Record 166 of
Title:Effect of near-field distribution on transmission characteristics of fiber-fed Fabry-Perot etalons
Author(s):Hao, Jun(1,2,3); Tang, Liang(1,2); Ye, Huiqi(1,2); Hao, Zhibo(1,2,3); Han, Jian(1,2); Zhai, Yang(1,2); Zhang, Kai(1,2); Wei, Ruyi(4); Xiao, Dong(1,2)Source: arXiv Volume: Issue: DOI: null Published: May 10, 2021Abstract:Fiber-fed etalons are widely employed in advanced interferometric instruments such as gravitational-wave detectors, ultrastable lasers and calibration reference for high-precision spectrographs. We demonstrate that variation in near-field distribution of the feeding fiber would deteriorate the spectrum precision of the fiber-fed Fabry-Perot etalon, especially when precision at the order of 3 × 10?10 or higher is required. The octagonal fiber reinforced with double scrambler could greatly improve the steadiness and uniformness of the near-field distribution. When building wavelength calibrators for sub-m s?1 precision radial-velocity instruments, the double scrambler should be considered meticulously. Copyright ? 2021, The Authors. All rights reserved.Accession Number: 20210117262 -
Record 167 of
Title:Two-center interference and stereo Wigner time delay in photoionization of asymmetric molecules
Author(s):Liao, Yijie(1); Zhou, Yueming(1); Pi, Liang-Wen(2,3); Ke, Qinghua(1); Liang, Jintai(1); Zhao, Yong(1); Li, Min(1); Lu, Peixiang(1,4,5)Source: Physical Review A Volume: 104 Issue: 1 DOI: 10.1103/PhysRevA.104.013110 Published: July 2021Abstract:We present numerical simulations of the time delay in photoemission of asymmetric diatomic molecules using the technique of reconstruction of attosecond beating by interference of two-photon transitions (RABITT) by solving the time-dependent Schr?dinger equation. Our results show an obvious time delay between photoelectrons emitted to the left and right and this relative time delay oscillates as the photoelectron energy changes. More interestingly, the amplitude of this oscillation increases when the asymmetry degree of diatomic molecules decreases. With the method of the selected continuum wave functions, we calculate the Wigner time delay in photoionization. The obtained stereo Wigner time delay also oscillates with photoelectron energy. This oscillation is traced back to two-center interferences and it could explain the relative time delay in the RABITT measurement. Furthermore, our results indicate that the continuum-continuum time delay in photoemission of heteronuclear molecules is asymmetric. ? 2021 American Physical SocietyAccession Number: 20213110717603 -
Record 168 of
Title:The centroid extraction algorithm of sun based on multi-color model
Author(s):Ma, Ling(1,2); Qiao, Weidong(1); Wang, Hui(3)Source: Proceedings of SPIE - The International Society for Optical Engineering Volume: 12065 Issue: DOI: 10.1117/12.2606559 Published: 2021Abstract:This paper proposes a method for extracting the solar centroid based on a multi-color model. The method is based on the three-color models (Lab, HIS, RGB) to segment and extract the color features of the image at the same time, coarsely locate the existence area of the sun target, and filter the obtained results through shape features, etc. We should try our best to optimize algorithm, for which can obtain a precise sun image. It is very important to combine circle center fitting with edge extraction to obtain the coordinate of edge point. What's more, we need to select the edge points to form a sample set of edge points. It is helpful to fit the center of the circle by the least square method. The algorithm is improved to find the center of mass of the sun. By subjective judgment and error analysis evaluation of a large number of results, this method is useful as we expecting for the segmentation and extraction of solar targets. But due to the interference of the shooting angle, light, exposure, weather and other factors when the image was taken, which makes the result of target segmentation not ideal. However, it has little effect on the final centroid extraction result. ? 2021 SPIE.Accession Number: 20220211438133