Table of Content

20 April 2015, Volume 44 Issue 4

Previous Issue    Next Issue

Downward Continuation of Airborne Gravimetry on Land Using Geopotential Model and Terrain Information

HUANG Motao, NING Jinsheng, OUYANG Yongzhong, DENG Kailiang, ZHAI Guojun, LU Xiuping, WU Taiqi

2015, 44(4):  355-362.  doi:10.11947/j.AGCS.2015.20130751

Asbtract ( )   HTML   PDF (1136KB) ( )  

References | Related Articles | Metrics

In order to evade the ill-posedness of downward continuation for airborne gravity data using traditional inverse Poisson integral, in a recent published article,a practical downward continuation method of airborne gravity data was used for the sea surveying areas using the differential conception in navigation and location for reference, in which the continuation corrections are calculated using ultra-high-degree geopotential model. In this paper, we continue using the same idea and develop the method to the application for land surveying areas. It suggests that terrain Information can be used to improve the calculated accuracy of continuation correction from geopotential model. The differential of local topographic corrections on flying height and corresponding ground point is added to the continuation correction from geopotential model, and it makes up the total continuation correction. It is ultimately realized to continue airborne gravity measurements to the ground in full frequency extension. EGM2008 geopotential model, ground gravity data and digital elevation model in high resolution are used as a case study to prove the efficiency of the new method.

Inference of Altimeter Accuracy on Along-track Gravity Anomaly Recovery

LI Yang, ZHANG Running

2015, 44(4):  363-369.  doi:10.11947/j.AGCS.2015.20140022

Asbtract ( )   HTML   PDF (1398KB) ( )  

References | Related Articles | Metrics

A correlation model between along-track gravity anomaly accuracy, spatial resolution and altimeter accuracy is proposed. This new model is based on along-track gravity anomaly recovery and resolution estimation. Firstly, an error propagation formula of along-track gravity anomaly is derived from the principle of satellite altimetry. Then the mathematics between the SNR (signal to noise ratio) and cross spectral coherence is deduced. The analytical correlation between altimeter accuracy and spatial resolution is finally obtained from the results above. Numerical simulation results show that along-track gravity anomaly accuracy is proportional to altimeter accuracy, while spatial resolution has a power relation with altimeter accuracy. e.g., with altimeter accuracy improving m times, gravity anomaly accuracy improves m times while spatial resolution improves m^0.4644 times. This model is verified by real-world data.

Probability Model of Center-of-mass Calibration of Satellites' Retro-reflectors Used for Laser Ranging

ZHAO Qunhe, WANG Xiaoya, HE Bing, ZHANG Zhongping, CHEN Wanzhen, CHEN Hongyu, JIANG Hu, HU Xiaogong

2015, 44(4):  370-376.  doi:10.11947/j.AGCS.2015.20130338

Asbtract ( )   HTML   PDF (1321KB) ( )  

References | Related Articles | Metrics

Satellite laser ranging system calculates the distance from ground-based observatories to satellites using the round-trip travel time of laser pulse. The position of retro-reflectors on satellites needs to be corrected which is helpful to improvie the measuring precision of satellite laser ranging. The correction errors of center-of-mass(CoM)are mainly caused by the distribution effects of retro-reflectors on satellites.CoM is related to incident angle, structural alignment of retro-reflectors and ground-based position. Based on the reflecting probability of photons for retro-reflectors is proportional to the cross sections of retro-reflectors, the cross section area of corner reflectors is fitted and the probabilistic model is established using incident angle as the random variable. The corrections of CoMs of spherical satellite such as LAGEOS-1/2 are calculated and different CoM values are applied for SLR precise orbit determination using long-term full rate observation data with different WRMS results analyzed. At last, for the planar array retro-reflectors, the CoMs of BeiDou navigational satellite such as BeiDou-M3 are also calculated and analyzed using one month SLR full rate data. The result shows that the calculated CoMs based on probability theory have the comparative precision in SLR precise orbit determination.

The PPP Precision Analysis Based on BDS Regional Navigation System

ZHU Yongxing, FENG Laiping, JIA Xiaolin, ZHANG Qinghua, RUAN Rengui

2015, 44(4):  377-383.  doi:10.11947/j.AGCS.2015.20140082

Asbtract ( )   HTML   PDF (2218KB) ( )  

References | Related Articles | Metrics

BeiDou navigation satellite system(BDS) has opened service in most of the Asia-Pacific region, it offers the possibility to break the technological monopoly of GPS in the field of high-precision applications, so its performance of precise point positioning (PPP) has been a great concern. Firstly, the constellation of BeiDou regional navigation system and BDS/GPS tracking network is introduced. Secondly, the precise ephemeris and clock offset accuracy of BeiDou satellite based on domestic tracking network is analyzed. Finally, the static and kinematic PPP accuracy is studied, and compared with the GPS. The actual measured numerical example shows that the static and kinematic PPP based on BDS can achieve centimeter-level and decimeter-level respectively, reaching the current level of GPS precise point positioning.

Neural Network Aided Adaptive UKF Algorithm for GPS/INS Integration Navigation

TAN Xinglong, WANG Jian, ZHAO Changsheng

2015, 44(4):  384-391.  doi:10.11947/j.AGCS.2015.20140216

Asbtract ( )   HTML   PDF (5763KB) ( )  

References | Related Articles | Metrics

The predicted residual vectors should be zero-mean Gaussian white noise, which is the precondition for multiple fading factors adaptive filtering algorithm based on statistical information in GPS/INS integration system. However the abnormalities in observations will affect the distribution of the residual vectors. In this paper, a neural network aided adaptive unscented Kalman filter (UKF) algorithm with multiple fading factors based on singular value decomposition(SVD) is proposed. The algorithm uses the neural network algorithm to weaken the influence of the observed abnormalities on the residual vectors. Singular value decomposition instead of unscented transformation is adopted to suppress negative definite variation in priori covariance matrix of UKF. Since single fading factor in poor tracking of multiple variables has the limitation, multiple fading factors to adjust the predicted-state covariance matrix are constructed with better robustness so that each filter channel has different adjustability. Finally, vehicle measurement data are collected to validate the proposed algorithm. It shows that the neural network algorithm can prevent the observed abnormalities from affecting the distribution of the residual vectors, expanding the applied range of the adaptive algorithm. The neural network algorithm aided SVD-UKF algorithm with multiple fading factors is able to remove influences of state anomalies on condition of the observed abnormalities. The accuracy and reliability of the navigation solution can be improved by this algorithm.

High-performance Atomic Clock Modeling and Its Application in Precise Point Positioning

ZHANG Xiaohong, CHEN Xinghan, GUO Fei

2015, 44(4):  392-398.  doi:10.11947/j.AGCS.2015.20140287

Asbtract ( )   HTML   PDF (1498KB) ( )  

References | Related Articles | Metrics

Presently, many IGS tracking stations have been equipped with high performance atomic clocks. In this paper, the modified Allan variance method is used to analyze the time-domain characterization of random noise of receiver clocks from different IGS tracking stations. Then, we not only evaluate the short-term stability of different types of receiver clock and the feasibility of clock modeling, but also take advantage of the observational data of Active Hydrogen Maser from IGS station in order to constrain random variation of receiver clock offset by implementing short-term clock modeling in precise point positioning(PPP) algorithm and improve positioning performance of PPP. The experiment results show that the method of clock modeling reduces the correlation between the height component, the zenith path delay and receiver clock offset parameter, the accuracy of height component can be improved by 50%. The proposed method can improve the PPP performance in crustal deformation monitoring, LEO satellite orbit determination, GNSS methodology and many other high precise GNSS geoscience fields when a high-performance atomic clock is deployed.

Detection of ZY-3 Satellite Platform Jitter Using Multi-spectral Imagery

ZHU Ying, WANG Mi, PAN Jun, HU Fen

2015, 44(4):  399-406.  doi:10.11947/j.AGCS.2015.20140024

Asbtract ( )   HTML   PDF (4256KB) ( )  

References | Related Articles | Metrics

Satellite platform jitter is one of the factors that affect the quality of high resolution imagery, which can cause image blur and internal distortion. Taking ZiYuan-3 (ZY-3) multi-spectral camera as a prototype, this paper proposes a satellite platform jitter detection method by utilizing multi-spectral imagery. First, imaging characteristics of multispectral camera and the main factors affecting band-to-band registration error are introduced. Then the regularity of registration error caused by platform jitter is analyzed by theoretical derivation and simulation. Meanwhile, the platform jitter detection method based on high accuracy dense points matching is presented. Finally, the experiments were conducted by using ZY-3 multi-spectral imagery captured in different time. The result indicates that ZY-3 has a periodic platform jitter about 0.6 Hz in the imaging period of test data, and the jitter amplitude across track is greater than that along track, which causes periodic band-to-band registration error with the same frequency. The result shows the possibility of the improvement in geometric processing accuracy for ZY-3 imagery products and provides an important reference for satellite platform jitter source analysis and satellite platform design optimization.

Contour Cluster Shape Analysis for Building Damage Detection from Post-earthquake Airborne LiDAR

HE Meizhang, ZHU Qing, DU Zhiqiang, ZHANG Yeting, HU Han, LIN Yueguan, QI Hua

2015, 44(4):  407-413.  doi:10.11947/j.AGCS.2015.20130785

Asbtract ( )   HTML   PDF (1722KB) ( )  

References | Related Articles | Metrics

Detection of the damaged building is the obligatory step prior to evaluate earthquake casualty and economic losses. It's very difficult to detect damaged buildings accurately based on the assumption that intact roofs appear in laser data as large planar segments whereas collapsed roofs are characterized by many small segments. This paper presents a contour cluster shape similarity analysis algorithm for reliable building damage detection from the post-earthquake airborne LiDAR point cloud. First we evaluate the entropies of shape similarities between all the combinations of two contour lines within a building cluster, which quantitatively describe the shape diversity. Then the maximum entropy model is employed to divide all the clusters into intact and damaged classes. The tests on the LiDAR data at El Mayor-Cucapah earthquake rupture prove the accuracy and reliability of the proposed method.

A Quick and Affine Invariance Matching Method for Oblique Images

XIAO Xiongwu, GUO Bingxuan, LI Deren, ZHAO Xia, JIANG Wanshou, HU Han, ZHANG Chunsen

2015, 44(4):  414-421.  doi:10.11947/j.AGCS.2015.20140048

Asbtract ( )   HTML   PDF (2116KB) ( )  

References | Related Articles | Metrics

This paper proposed a quick, affine invariance matching method for oblique images. It calculated the initial affine matrix by making full use of the two estimated camera axis orientation parameters of an oblique image, then recovered the oblique image to a rectified image by doing the inverse affine transform, and left over by the SIFT method. We used the nearest neighbor distance ratio(NNDR), normalized cross correlation(NCC) measure constraints and consistency check to get the coarse matches, then used RANSAC method to calculate the fundamental matrix and the homography matrix. And we got the matches that they were interior points when calculating the homography matrix, then calculated the average value of the matches' principal direction differences. During the matching process, we got the initial matching features by the nearest neighbor(NN) matching strategy, then used the epipolar constrains, homography constrains, NCC measure constrains and consistency check of the initial matches' principal direction differences with the calculated average value of the interior matches' principal direction differences to eliminate false matches. Experiments conducted on three pairs of typical oblique images demonstrate that our method takes about the same time as SIFT to match a pair of oblique images with a plenty of corresponding points distributed evenly and an extremely low mismatching rate.

False Detection of Relative Orientation of Multi-view Images Based on Belief Propagation

LU Jun, ZHANG Baoming, GUO Haitao, ZHANG Hongwei

2015, 44(4):  422-430.  doi:10.11947/j.AGCS.2015.20140255

Asbtract ( )   HTML   PDF (3760KB) ( )  

References | Related Articles | Metrics

Ambiguous visual structures or repetitive textures of different scenarios would result in a large number of mismatching points in image matching stage, and false positive relative orientation is introduced which is locally consistent.In this paper, the probabilistic inference method is introduced and an improved detection algorithm of false positive relative orientations is presented. A Bayes network based on relative orientations between images is constructed using closed cycle constraints and priori probability models in Bayes network is derived and the maximum posterior probability in Bayesian network is solved using belief propagation algorithm. Experimental results show that using the proposed global consistency constraints method can effectively detect the false positive relative orientations and improve outcomes of scene reconstruction with high computational efficiency.

An Approach for Automatic Orientation of Big Point Clouds from the Stationary Scanners Based on the Spherical Targets

YAO Jili, MA Ning, JIA Xiangyang, XU Guangpeng, XIE Jianchun

2015, 44(4):  431-437.  doi:10.11947/j.AGCS.2015.20130357

Asbtract ( )   HTML   PDF (1460KB) ( )  

References | Related Articles | Metrics

Terrestrial laser scanning (TLS) technology has high speed of data acquisition, large amount of point cloud, long distance of measuring. However, there are some disadvantages such as distance limitation in target detecting, hysteresis in point clouds processing, low automation and weaknesses of adapting long-distance topographic survey. In this case, we put forward a method on long-range targets detecting in big point clouds orientation. The method firstly searches point cloud rings that contain targets according to their engineering coordinate system. Then the detected rings are divided into sectors to detect targets in a very short time so as to obtain central coordinates of these targets. Finally, the position and orientation parameters of scanner are calculated and point clouds in scanner's own coordinate system(SOCS) are converted into engineering coordinate system. The method is able to be applied in ordinary computers for long distance topographic(the distance between scanner and targets ranges from 180 to 700 m) survey in mountainous areas with targets radius of 0.162m.

Representation Model of Topological Relations between Complex Planar Objects

CHEN Zhanlong, FENG Qiqi, WU Xincai

2015, 44(4):  438-444.  doi:10.11947/j.AGCS.2015.20130708

Asbtract ( )   HTML   PDF (1832KB) ( )  

References | Related Articles | Metrics

In order to express the details of the topological relations between complex planar objects, the classic 9-intersection model is improved and the two extended 9-intersection models that based on decomposition ideas are proposed: the one 9-intersection model method that is decomposed into simple area has its advantage of simplification, but at the cost of complicated expressions; another 9-intersection model method that is decomposed into point-set, conforming well with the classical 9-intersection model, but has relatively complex calculations. Compared the expressive abilities between the two kinds of extened 9-intersection models and the classic 9-intersection model by examples. The results show that both the two extended 9-intersection models can give more accurately expression of the topological relations between details of the sub parts in complex planar objects, the expressive ability of 9-intersection model has been expanded and improved.

A Node-degree Based Line/Polygon Topological Relationship Refinement Model and Its Application

ZHOU Xiaoguang, CHEN Fei, CHEN Jun

2015, 44(4):  445-452.  doi:10.11947/j.AGCS.2015.20140138

Asbtract ( )   HTML   PDF (1721KB) ( )  

References | Related Articles | Metrics

In order to overcome the shortcoming of the current models in discriminating the refined topological relations between line and polygon, a node-degree based refined line/polygon topological relationship model is presented. In this model, the unit line/polygon intersection segment is defined at first,then node-degree is introduced to refine the unit intersection segment. 21 refinement line/polygon intersection segment types are differentiated using the degree of the end points of the intersection segment, and the relationship between the polygon and the next segment of the line object at the end point(s) with 3 or 4 degree values.The comparison is carried out between the proposed node-degree based model and the current model. The discrimination of the refined line/polygon relations with multiple intersections is described using an example. The effectiveness of this model is verified by the topological integrity checking between road and river data.

Road Network Selection Based on Road Hierarchical Structure Control

HE Haiwei, QIAN Haizhong, LIU Hailong, WANG Xiao, HU Huiming

2015, 44(4):  453-461.  doi:10.11947/j.AGCS.2015.20130787

Asbtract ( )   HTML   PDF (4675KB) ( )  

References | Related Articles | Metrics

A new road network selection method based on hierarchical structure is studied. Firstly, road network is built as strokes which are then classified into hierarchical collections according to the criteria of betweenness centrality value (BC value). Secondly, the hierarchical structure of the strokes is enhanced using structural characteristic identification technique. Thirdly, the importance calculation model was established according to the relationships among the hierarchical structure of the strokes. Finally, the importance values of strokes are got supported with the model's hierarchical calculation, and with which the road network is selected. Tests are done to verify the advantage of this method by comparing it with other common stroke-oriented methods using three kinds of typical road network data. Comparision of the results show that this method had few need to semantic data, and could eliminate the negative influence of edge strokes caused by the criteria of BC value well. So, it is better to maintain the global hierarchical structure of road network, and suitable to meet with the selection of various kinds of road network at the same time.

Quickly Planning TF/TA² Trajectory by Artificial Immune Algorithm

LIU Lifeng, YANG Fei, ZHANG Shuqing, KONG Weihua, WANG Yinxing

2015, 44(4):  462-470.  doi:10.11947/j.AGCS.2015.20120523

Asbtract ( )   HTML   PDF (3545KB) ( )  

References | Related Articles | Metrics

Flight path planning by artificial immune algorithm approach met the requirements of aircraft's flyability and operation is proposed for the problem of single and double TF/TA² flight path planning. Punishment function (affinity function) with comprehensive 3D threat information is designed. A comprehensive threat model is formed including dynamic and static threats and no-fly-zone. Accordingly, single and dual flight paths are planned by AIA, which have been compared with the paths by GA. The results show that, GA's planned a quick and longer path compared under simple threat environment; in complex environments, GA has high failure rate (greater than 95%) for single aircraft, but it is failed for double aircrafts. For the single and double aircrafts, AIA can provides one optimal and more candidate optimal flight paths.

Research on High-Precision Methods of Visual Measurement of the Shape and Size of the Industrial Parts

GUO Baoyun

2015, (4):  471-471.  doi:10.11947/j.AGCS.2015.20140457

Asbtract ( )   HTML   PDF (679KB) ( )  

Related Articles | Metrics

Research on Key Technology of Handheld Photography Scanning System Based on Structured Light

LI Cailin

2015, (4):  472-472.  doi:10.11947/j.AGCS.2015.20140458

Asbtract ( )   HTML   PDF (678KB) ( )  

Related Articles | Metrics