中国科学院机构知识库网格系统: 检索

基于地震观测记录的地质灾害事件检测——以“23.7”北京山洪泥石流为例 期刊论文 OAI收割
地球与行星物理论评(中英文), 2025, 卷号: N/A, 期号: 0, 页码: 1-12
作者: 王烁帆; 崔一飞; 邓雄涛; 李尧; 张勇刚

|

收藏 | 浏览/下载：50/0 | 提交时间：2025/07/04

"23.7" Beijing flush flood and debris flow seismic signal processing based on centroid frequency detection method

Adaptive quasi-Monte Carlo method for uncertainty evaluation in centroid measurement of planetary rovers 期刊论文 OAI收割
Transactions of the Institute of Measurement and Control, 2021, 卷号: 43, 期号: 3, 页码: 623-634
作者: Na Q(那强); Hu SR(胡淑荣); Tao JG(陶建国); Luo Y(罗阳)

|

收藏 | 浏览/下载：60/0 | 提交时间：2020/09/26

Uncertainty evaluation adaptive quasi-Monte Carlo method Monte Carlo method planetary rover centroid measurement

Optimum parameters of image preprocessing method for Shack-Hartmann wavefront sensor in different SNR condition 会议论文 OAI收割
Nanjing, PEOPLES R CHINANanjing, PEOPLES R CHINA, OCT 24-26, 2017OCT 24-26, 2017
作者: Wei, Ping; Li, Xinyang; Luo, Xi; Li, Jianfeng

|

收藏 | 浏览/下载：78/0 | 提交时间：2019/08/23

SH-WFS centroid method SNR Thresholding method Windowing method

A shape context based Hausdorff similarity measure in image matching 会议论文 OAI收割
5th International Symposium on Photoelectronic Detection and Imaging (ISPDI) - Infrared Imaging and Applications, Beijing, June 25-27, 2013
作者: Ma TL(马天磊); Liu YP(刘云鹏); Shi ZL(史泽林); Yin J(尹健)

收藏 | 浏览/下载：62/0 | 提交时间：2013/12/26

The traditional Hausdorff measure, which uses Euclidean distance metric (L2 norm) to define the distance between coordinates of any two points, has poor performance in the presence of the rotation and scale change although it is robust to the noise and occlusion. To address the problem, we define a novel similarity function including two parts in this paper. The first part is Hausdorff distance between shapes which is calculated by exploiting shape context that is rotation and scale invariant as the distance metric. The second part is the cost of matching between centroids. Unlike the traditional method, we use the centroid as reference point to obtain its shape context that embodies global information of the shape. Experiment results demonstrate that the function value between shapes is rotation and scale invariant and the matching accuracy of our algorithm is higher than that of previously proposed algorithm on the MEPG-7 database.

Research on infrared dim-point target detection and tracking under sea-sky-line complex background (EI CONFERENCE) 会议论文 OAI收割
International Symposium on Photoelectronic Detection and Imaging 2011: Advances in Infrared Imaging and Applications, May 24, 2011 - May 24, 2011, Beijing, China
作者: Dong Y.-X.; Zhang H.-B.; Li Y.; Li Y.; Li Y.

收藏 | 浏览/下载：133/0 | 提交时间：2013/03/25

Target detection and tracking technology in infrared image is an important part of modern military defense system. Infrared dim-point targets detection and recognition under complex background is a difficulty and important strategic value and challenging research topic. The main objects that carrier-borne infrared vigilance system detected are sea-skimming aircrafts and missiles. Due to the characteristics of wide field of view of vigilance system the target is usually under the sea clutter. Detection and recognition of the target will be taken great difficulties.There are some traditional point target detection algorithms such as adaptive background prediction detecting method. When background has dispersion-decreasing structure the traditional target detection algorithms would be more useful. But when the background has large gray gradient such as sea-sky-line sea waves etc.The bigger false-alarm rate will be taken in these local area.It could not obtain satisfactory results. Because dim-point target itself does not have obvious geometry or texture feature in our opinion from the perspective of mathematics the detection of dim-point targets in image is about singular function analysis.And from the perspective image processing analysis the judgment of isolated singularity in the image is key problem. The foregoing points for dim-point targets detection its essence is a separation of target and background of different singularity characteristics.The image from infrared sensor usually accompanied by different kinds of noise. These external noises could be caused by the complicated background or from the sensor itself. The noise might affect target detection and tracking. Therefore the purpose of the image preprocessing is to reduce the effects from noise also to raise the SNR of image and to increase the contrast of target and background. According to the low sea-skimming infrared flying small target characteristics the median filter is used to eliminate noise improve signal-to-noise ratio then the multi-point multi-storey vertical Sobel algorithm will be used to detect the sea-sky-line so that we can segment sea and sky in the image. Finally using centroid tracking method to capture and trace target. This method has been successfully used to trace target under the sea-sky complex background. 2011 Copyright Society of Photo-Optical Instrumentation Engineers (SPIE).

Study on medical X-ray coherent scatter imaging and processing based digital flat detector (EI CONFERENCE) 会议论文 OAI收割
3rd International Conference on BioMedical Engineering and Informatics, BMEI 2010, October 16, 2010 - October 18, 2010, Yantai, China
作者: Li B.; Zhao J.; Li B.; Li B.; Liu J.

收藏 | 浏览/下载：52/0 | 提交时间：2013/03/25

It is introduced a novel imaging technique for medical diagnostic X-ray coherent scatter in this paper. A set of experimental equipment for X-ray coherent scatter imaging was set up with X-ray digital flat detector and medical diagnostic X-ray source. According to this equipment the scatter images obtained are made of some circles with the same center. It is vital to calculate the energy template to classify the different samples. It is difficult to separate them using the traditional threshold method due to noise and overlapped shadow. In this paper the image was transformed a binary image by using K-Means algorithm and Mathematical Morphology Methods. The effective region was extracted from the binary image inside the orthogonal energy projection space then to calculate the centroid of rings. Consequently the curve of the energy distribution was built. The experiment results show that our method is reasonable and feasible. The technique will have wide foreground of application .Besides the imaging of human bone content it can be used for various imaging of tissue and organs in biology. 2010 IEEE.

Research on automatic Hartmann test of membrane mirror (EI CONFERENCE) 会议论文 OAI收割
5th International Symposium on Advanced Optical Manufacturing and Testing Technologies: Optical Test and Measurement Technology and Equipment, April 26, 2010 - April 29, 2010, Dalian, China
作者: Zhang P.

收藏 | 浏览/下载：60/0 | 提交时间：2013/03/25

Electrostatic membrane mirror is ultra-lightweight and easy to acquire a large diameter comparing with traditional optical elements so its development and usage is the trend of future large mirrors. In order to research the control method of the static stretching membrane mirror the surface configuration must be tested. However membrane mirror's shape is always changed by variable voltages on the electrodes and the optical properties of membrane materials using in our experiment are poor so it is difficult to test membrane mirror by interferometer and null compensator method. To solve this problem an automatic optical test procedure for membrane mirror is designed based on Hartmann screen method. The optical path includes point light source CCD camera splitter and diffuse transmittance screen. The spots' positions on the diffuse transmittance screen are pictured by CCD camera connected with computer and image segmentation and centroid solving is auto processed. The CCD camera's lens distortion is measured and fixing coefficients are given to eliminate the spots' positions recording error caused by lens distortion. To process the low sampling Hartmann test results Zernike polynomial fitting method is applied to smooth the wave front. So low frequency error of the membrane mirror can be measured then. Errors affecting the test accuracy are also analyzed in this paper. The method proposed in this paper provides a reference for surface shape detection in membrane mirror research. 2010 Copyright SPIE - The International Society for Optical Engineering.

High accuracy star image locating and imaging calibration for star sensor technology (EI CONFERENCE) 会议论文 OAI收割
6th International Symposium on Precision Engineering Measurements and Instrumentation, August 8, 2010 - August 11, 2010, Hangzhou, China
作者: Wang Y.; Wang Y.; Wang Y.; Wang Y.; Wang Y.

收藏 | 浏览/下载：40/0 | 提交时间：2013/03/25

Today aircraft attitude measurement technology plays an important role in an aircraft system because it can provide orientation for aircraft in action. Lately star sensor technology used in aircraft attitude measurement has become more and more popular because of its high accuracy light weight without attitude accumulation errors and other advantages. There are three main steps for star sensor to measure aircraft attitude star image locating star identification and attitude tracking. The latter two steps are based on the accuracy of star image locating. So it's critical to make efforts to advance the accuracy of star image locating. Some imaging errors such as spherical aberration or coma aberration also have negative effect on the accuracy of star image locating of which the effect is necessarily reduced as well. At the beginning of this article the structure of star sensor hardware is introduced. Secondly three methods for star image locating are described specifically which are traditional centroid method Gauss quadric fitting method and improved Gauss quadric fitting method. Subsequently an imaging calibration method is described for the purpose of reducing the effect of imaging errors. Finally the experiment shows that the accuracy of the star sensor is 2-arc-second. 2010 SPIE.

Research on tracking approach to low-flying weak small target near the sea (EI CONFERENCE) 会议论文 OAI收割
ICO20: Optical Information Processing, August 21, 2005 - August 26, 2005, Changchun, China
作者: Xue X.-C.

收藏 | 浏览/下载：60/0 | 提交时间：2013/03/25

Automatic target detection is very difficult in complicate background of sea and sky because of the clutter caused by waves and clouds nearby the sea-level line. In this paper in view of the low-flying target near the sea is always above the sea-level line we can first locate the sea-level line and neglect the image data beneath the sea-level line. Thus the noise under the sea-level line can be suppressed and the executive time of target segmentation is also much reduced. A new method is proposed which first uses neighborhood averaging method to suppress background and enhance targets so as to increase SNR and then uses the multi-point multi-layer vertical Sobel operator combined with linear least squares fitting to locate the sea-level line lastly uses the centroid tracking algorithm to detect and track the target. In the experiment high frame rate and high-resolution digital CCD camera and high performance DSP are applied. Experimental results show that this method can efficiently locate the sea-level line on various conditions of lower contrast and eliminate the negative impact of the clutter caused by waves and clouds and capture and track target real-timely and accurately.

Active pixel sensor geometrical characteristic effects on star image subdivided locating accuracy for star tracker (EI CONFERENCE) 会议论文 OAI收割
ICO20: Remote Sensing and Infrared Devices and Systems, August 21, 2005 - August 26, 2005, Changchun, China
作者: Liu J.; Liu J.; Liu J.; Li J.; Li J.

收藏 | 浏览/下载：55/0 | 提交时间：2013/03/25

Active pixel sensor (APS) star tracker becomes an investigated hotspot because of its technical advantages. And centroid algorithm is a subpixel method proper to star position calculation because of its high accuracy and simplicity. When centroid algorithm is applied on APS star tracker APS pixel geometrical characteristics might effect on star image position accuracy. Because the amplifier circuit and other function circuits inter pixel of APS take up some pixel area the Fill Factor is less than 100%. Moreover the active sensitive area has a certain geometrical shape such as square rectangle and L shape. The Fill Factor of pixel influences on star image subdivided locating accuracy when using centioid algorithm. In this paper we have analyzed all pixel geometrical characteristics influence on the star position accuracy. From simulation experiments we can conclude that Fill factor and pixel geometric shape influence on star position accuracy. The star locating error increased when Fill Factor decreased and different geometrical shape of active sensitive area of pixel can make different influence on star location accuracy the symmetrical sensitive area in x or y axis have symmetrical location error in the same axis.