2017
2017
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Record 409 of
Title:Taylor series-based generic demosaicking algorithm for multispectral image
Author(s):Tonghan, Jia(1,2); Zhang, Geng(1); Liu, Xuebin(1)Source: Proceedings of SPIE - The International Society for Optical Engineering Volume: 10462 Issue: DOI: 10.1117/12.2285052 Published: 2017Abstract:Using coated mosaic video spectrometer to collect multispectral image which reduce the spectral information redundancy and data volume greatly and achieve real-Time data transmission conditions. The mosaic video spectrometer imaging technique use a similar mosaic template to capture all the pixels and output a two-dimensional multi-spectral image with dozens of spectral information. The image is divided into a certain size of matrix in its field, and each pixel in the pixel matrix is only for one wavelength information response and every pixel response for different wavelength. The size of the pixel matrix block depends on the number of spectral segments, which results in a low spatial resolution of the single spectral segment image and the spectral information of each pixel absenting severely. Therefore, to reconstruct the complete multi-spectral image, we must estimate and interpolate the missing spatial information and spectral information by demosaicking multispectral image. In this paper, we present a novel demosaicking method to produce the high resolution multispectral image and reconstruct missing spectrum information in high accuracy. The proposed method computes the first-And second-order derivatives of the original single multispectral image to measure the geometry of edges in the image and the spectrum value of missing pixel. Two metrics are used to evaluate the generic algorithm, including the structural similarity index-measurement system (SSIM) for reconstruction performance and the procession time. Experimental results show that the demosaicked images present higher SSIM (more than 0.9) and comparable calculated time performance as traditional ways. This algorithm brings the greatest advantage that make up for the weakness of mosaick multispectral image and reduce the data transmission process cost and storage needs. ? 2017 SPIE.Accession Number: 20180404670997 -
Record 410 of
Title:Feature Selection Based on Structure Preserving for Hyperspectral Image Combination with Multi-scale Spatial Filtering and Hierarchical Network
Author(s):Hou, Bang-Huan(1); Zhang, Geng(2); Wang, Fei(3); Yu, Wei-Zhong(1,3); Yao, Min-Li(1); Hu, Bing-Liang(2)Source: Guangzi Xuebao/Acta Photonica Sinica Volume: 46 Issue: 5 DOI: 10.3788/gzxb20174605.0510003 Published: May 1, 2017Abstract:In order to make full use of the abundant spectral and spatial information of hyperspectral images, a novel feature selection algorithm based on the structure preserving combination with the multi-scale spatial filtering and the hierarchical network is proposed. The feature subset that best preserving the global similarity and the local manifold structure is selected via l2, 1 norm mathematical model. The bilateral filtering with multi-scale window and adaptive parameter setting is used for incorporating spatial information into spectral data automatically, enhancing the similarity within class and dissimilarity between different classes. The hierarchical network is introduced to achieve further integration of spatial and spectral information that benefit the classification. The influence of the hierarchical network depth and spatial filtering scale number is analyzed. The experiments validate the effectiveness of the algorithm. The overall classification accuracies reaches to 90.98% and 94.20% on Indian Pines and PaviaU data sets respectively, which significantly improve the classification of land cover compared with conventional methods. ? 2017, Science Press. All right reserved.Accession Number: 20173104014265 -
Record 411 of
Title:A star image registration algorithm based on joint feature matching
Author(s):Li, Zhao(1,2); Wen, Yan(1)Source: Proceedings of SPIE - The International Society for Optical Engineering Volume: 10462 Issue: DOI: 10.1117/12.2283215 Published: 2017Abstract:With the amount of space debris increasing accordingly with human activities in near space, the threat of space debris to space missions raises the concern of surveillance of these malicious targets. Space target detection based on optical image is a feasible and effective solution for monitoring these malicious targets. However, as the observation platform is nonestationary, image obtained from the telescope need registration for further operation. In this paper, a star image registration algorithm based on joint feature matching is proposed. The star images are firstly denoised by filtering system. Then reference stars are preselected and their features are constructed. By matching the extracted features, a pool of star pairs is established. Transform parameters are derived from the locations of these matched pairs. Experimental results have validated the capability of our algorithm in pixel accurate star image registration. ? 2017 SPIE.Accession Number: 20180404670972 -
Record 412 of
Title:Aircraft relative attitude measurement based on binocular vision
Author(s):Zhao, Yincen(1,2); Zhang, Geng(1); Hu, Bingliang(1); Peng, Bo(1,2)Source: Proceedings of SPIE - The International Society for Optical Engineering Volume: 10462 Issue: DOI: 10.1117/12.2285028 Published: 2017Abstract:With the development of computer vision and image processing technology, vision measurement has been paid more and more attention. In the aviation field, estimating the relative attitude of aircraft using computer vision is important in aircraft flight-refueling, target tracking and positioning. However, the existing methods to measure the attitude of aircraft have some problems. In this paper, we propose to use binocular vision measurement method to acquire the attitude data of aircraft. This method has the advantages of simple realization and high practical value, which can also be widely used in visional measurement applications. ? 2017 SPIE.Accession Number: 20180404670996 -
Record 413 of
Title:Centric baffle design of partial field optical system
Author(s):Wang, Chenchen(1,2); Zou, Gangyi(1,2); Li, Ruichang(1,2); Fan, Xuewu(1)Source: Hongwai yu Jiguang Gongcheng/Infrared and Laser Engineering Volume: 46 Issue: 3 DOI: 10.3788/IRLA201746.0318002 Published: March 25, 2017Abstract:A partial field optical system baffle was designed and optimized. Partial field was non-symmetry along one direction, so a large number light tracing was needed to design the centric, which made it difficult to design. A method of footprint diagram was used to get the coordinate of special light in the space, the size of effective field and the part of baffle blocking light. The part blocking light was removed and a "duck mouth shaped" baffle was got, which can decrease the difficulty of design. By optimizing the design, length of final designed baffle was half of the former one, and reduced the size along Y direction, which can reduce more stray light to enter the later optical system directly. Baffle was modeled and simulated by Solidworks and TracePro software, the PST is about 10-9 when the off-axis angle is 30°, which is less than 5.59×10-7, the requirement of the system. The result of the simulation shows that using method of footprint diagram to design inner baffle of a partial field optical system is feasible. ? 2017, Editorial Board of Journal of Infrared and Laser Engineering. All right reserved.Accession Number: 20172203715584 -
Record 414 of
Title:Modeling and research of a space-based spacecraft infrared detection system
Author(s):Li, Wenhao(1,2); Liu, Zhaohui(1); Mu, You(1); Yang, Rui(1,2); Zhang, Xing(1,2)Source: Applied Optics Volume: 56 Issue: 9 DOI: 10.1364/AO.56.002428 Published: March 20, 2017Abstract:When a spacecraft is in orbit, it is almost impossible to check its working condition. Almost all payload would generate waste heat when working, which is usually ejected by a radiator. By observing the radiator, we can catch a glimpse of a spacecraft's inner information. A thorough model of a space-based infrared detection system is analyzed, taking the radiator into account, which, to the best of our knowledge, has seldom been considered. The calculation result shows that infrared radiation reflected by spacecraft is weak compared with the spacecraft's self-radiation in 8-12 μm, and the contrast ratio between the radiator and surrounding area could be the criterion for judging the working condition of a spacecraft. The limit of detection distance is also increased due the higher temperature of the radiator. ? 2017 Optical Society of America.Accession Number: 20171303498215 -
Record 415 of
Title:Comparative analysis of direct torque control and DTC based on sliding mode control for PMSM drive
Author(s):Meng, Lingnan(1,2); Yang, Xiaojun(1)Source: Proceedings of the 29th Chinese Control and Decision Conference, CCDC 2017 Volume: Issue: DOI: 10.1109/CCDC.2017.7978529 Published: July 12, 2017Abstract:This paper firstly introduces the mathematical equations of PMSM (permanent magnet synchronous motor), an overview of direct torque control (DTC) and a DTC based on sliding mode control for PMSM, and then builds PMSM control system simulation models with above two methods in MATLAB /Simulink environment. Finally, we got the starting response, torque ripple and load perturbation responses of DTC and SMC-DTC by comparison the simulation results of the two models. ? 2017 IEEE.Accession Number: 20173504090068 -
Record 416 of
Title:Sheared-beam imaging of object with depth information
Author(s):Lan, Fu-Yang(1,2); Luo, Xiu-Juan(1); Chen, Ming-Lai(1); Zhang, Yu(1); Liu, Hui(1)Source: Wuli Xuebao/Acta Physica Sinica Volume: 66 Issue: 20 DOI: 10.7498/aps.66.204202 Published: October 20, 2017Abstract:Sheared-beam imaging technique is a non-conventional imaging method which can be used to image remote objects through atmospheric turbulence without needing any adaptive optics. In this imaging technique, the target is coherently illuminated by three laser beams which are laterally sheared at the transmitter plane and arranged into an L shape. In addition, each beam is modulated by a slight frequency shift. The speckle intensity signals scattered from the target are received by a detector array, and then the image of target can be reconstructed by computer algorithm. By far, most of studies in this field have focused on two-dimensional imaging. In real conditions, however, the surface of targets we are concerned about reveals that different depths introduce various phase delays in the scattering signal from target. This delay causes the phase-shift errors to appear between the ideal target Fourier spectrum and the Fourier spectrum received by detector array. Finally, this would result in poor image quality and low resolution. In this study, a three-dimensional target imaging model is established based on the two-dimensional target imaging model. The influence of modulated beat frequency between sheared beam and reference beam is studied on the objects with depth information, and the result shows that large beat frequency may have an adverse effect on reconstructed images. The simulation we have developed for this three-dimensional imaging model uses three targets with different shapes. Each target is divided into several sub-blocks, and we set different depth values (within 10 m) for these blocks. Then beat frequencies are increased from 5 Hz to about 1 MHz, respectively. At each pair of frequencies, the reconstructed image is recorded. S?rehl ratio is used as the measure of the imaging quality. Computer simulation results show that the S?rehl ratio of reconstructed images descends with the increase of beat frequency, which is fully consistent with the theory of three-dimensional target imaging proposed before. Meanwhile, we find that the depth distribution of target also has an effect on imaging quality. As for actual space targets, the maximum depth is usually not more than 10 m. Compared with the influence caused by beat frequencies, the effect produced by depth distribution is negligible. Therefore when a space target is imaged, beat frequencies play the major role in reconstructing high-quality image. The results presented in this paper indicate that in order to achieve better imaging quality in the practical application, it is necessary to select the smallest beat frequency according to the detector performance and keep the candidate frequencies away from the low-frequency noise of the detector. ? 2017 Chinese Physical Society.Accession Number: 20174904504268 -
Record 417 of
Title:Simulation of NLOS (non-line-of-sight) 3D imaging system
Author(s):Tan, Jingjing(1,2); Su, Xiuqin(1); Wu, Jingyao(1,2); Wei, Zhaoqi(1,2)Source: Proceedings of SPIE - The International Society for Optical Engineering Volume: 10457 Issue: DOI: 10.1117/12.2284097 Published: 2017Abstract:This passage studies on theory and scene simulation of NLOS imaging. Based on math and physical properties, a simulation platform is built for a NLOS imaging system, including a femtosecond laser, a scanning galvo system, a lambertian surface, several hidden scenes, an ultrafast photodetector to transfer the intensity of laser echo signal to voltage value and a TCSPC module to produce intensity-time histograms. By the simulation platform on MATLAB, precise imaging of the scenes is accomplished. Results show that multi-path analysis using echo signal intensity versus time provides enough proof to reconstruct 3D geometry of a hidden scene. ? 2017 SPIE.Accession Number: 20180204627076 -
Record 418 of
Title:Effect of iodine (I2) on structural, thermal and optical properties of Ge-Sb-S chalcohalide host glasses and ones doped with Dy
Author(s):Guo, Quan(1,2); Xu, Yantao(1,2); Guo, Haitao(1,3); Xiao, Xusheng(1); Lin, Changgui(4); Cui, Xiaoxia(1); Wang, Pengfei(1); Gao, Fei(1); Lu, Min(1); Peng, Bo(1)Source: Journal of Non-Crystalline Solids Volume: 464 Issue: DOI: 10.1016/j.jnoncrysol.2017.03.024 Published: May 15, 2017Abstract:A serial (100???x)Ge25Sb10S65-xI (x?=?0, 5, 10, 15, 20, 25 and 30?wt%) chalcohalide glasses and ones doped with 0.1?wt% Dy3?+ rare-earth ions were synthesized and their structural, thermal and optical properties were systematically studied. It indicates that addition of I2 into Ge25Sb10S65 glass significantly decreases the connectivity of glass network and average bond energy, and modifies the associated properties. The glass transition temperature and refractive index decrease monotonically, and the density increases almost linearly with the increasing of iodine content in glass. The thermal stability is improved, which has a maximum of ΔTmax?=?174?°C. While the optical bandgap has a peak value at x?=?10?wt%. The absorption spectra and mid-infrared fluorescence spectra of Dy3?+ rare-earth ions doped glasses were investigated together with the Judd-Ofelt analysis. GeS2 nano-crystals were found in the sample with x?≥?15?wt%, which is supposed to induce enhancements of mid-infrared fluorescence at 2.95 and 4.32?μm. ? 2017 Elsevier B.V.Accession Number: 20171203489690 -
Record 419 of
Title:Decoding techniques of single-ring absolute photoelectric shaft encoder
Author(s):Su, Xiaogang(1,2); Hu, Xiaodong(1); Xiao, Maosen(1); Zhang, Xiaodong(1)Source: Hongwai yu Jiguang Gongcheng/Infrared and Laser Engineering Volume: 46 Issue: 4 DOI: 10.3788/IRLA201746.0411007 Published: April 25, 2017Abstract:In comparison with incremental and traditional absolute encoder, the single-ring absolute encoder processes more advantage. And the research of decoding system and algorithm are essential to the single-ring absolute encoder. In order to improve single-ring absolute photoelectric encoder's circuit integration, response speed and accuracy, a decoding system was designed in this paper. Linear CCD was used in this system as the disc image receiving and photoelectric conversion device which also provided the basement of subdivision algorithm. And FPGA was used to achieve circuit control and decoding algorithm. A new decoding algorithm was also proposed in this paper. On the one hand, the coding information was achieved by counting high electrical level of the binaryzation signal of CCD's output. Coding information was obtained by recognition of the disc image and combination of 12-bits coding number. On the other hand, precise value was obtained by calculating the shifting between the centroid of image and virtual center. The centroid of stripe was calculated based on CCD centroid location algorithm. Finally, the value of angle was precisely received from combination of these two values. A prototype of theodolite was developed based on this single-ring absolute encoder decoding system and can reach the accuracy of 2". ? 2017, Editorial Board of Journal of Infrared and Laser Engineering. All right reserved.Accession Number: 20172703889327 -
Record 420 of
Title:Characteristics of External Optical Feedback in Distributed Feedback Fiber Lasers Array
Author(s):Hao, Ge-Yang(1,2); Wu, Guo-Jun(1); Lü, Pei(1); Wang, Hao(1); Liu, Bo(1)Source: Guangzi Xuebao/Acta Photonica Sinica Volume: 46 Issue: 4 DOI: 10.3788/gzxb20174604.0414001 Published: April 1, 2017Abstract:The simulation results between different facet reflectivity of external cavity and output power of distributed feedback fiber laser are presented, based on compound cavity laser model and facet reflectivity of external cavity measured by optical spectrum analyzers. And a two elements experiment system is constructed to prove this relationship. It is found that the output power of distributed feedback fiber laser will be increased and the flatness of distributed feedback fiber lasers array will be worsed due to the external optical feedback. And the larger facet reflectivity of external cavity is, the lower flatness of distributed feedback fiber lasers array will be. The influence of external optical feedback to the flatness of distributed feedback fiber lasers array should be considered, and distributed feedback fiber laser which have lower facet reflectivity should be used for constitutes the distributed feedback fiber lasers array. ? 2017, Science Press. All right reserved.Accession Number: 20172803903569