Table of Content

20 August 2016, Volume 45 Issue 8

Previous Issue    Next Issue

Construction Method of Regularization by Singular Value Decomposition of Design Matrix

LIN Dongfang, ZHU Jianjun, SONG Yingchun, HE Yonghong

2016, 45(8):  883-889.  doi:10.11947/j.AGCS.2016.20150134

Asbtract ( )   HTML   PDF (1611KB) ( )  

References | Related Articles | Metrics

Tikhonov regularization introduces regularization parameter and stable functional to improve the ill-condition. When the stable functional expressed as two-norm constraint, the regularization method is the same as ridge estimation. The analysis of the variance and bias of the ridge estimation shows that ridge estimation improved the ill-condition but introduced more bias. The estimation reliability is lowered. We get that correct the larger singular values cannot decrease the variance effectively but introduced more bias, correcting the smaller singular values can decrease the variance effectively. We choose the eigenvectors of the smaller singular values to construct the regularization matrix. It can adjust the correction of the singular values, decrease the variance and biases and finally get a more reliable estimation.

Weighted Total Least Squares of Universal EIV Adjustment Model

ZENG Wenxian, FANG Xing, LIU Jingnan, YAO Yibin

2016, 45(8):  890-894.  doi:10.11947/j.AGCS.2016.20150156

Asbtract ( )   HTML   PDF (935KB) ( )  

References | Related Articles | Metrics

This paper proposes the universal errors-in-variables (EIV) adjustment model based on the fundamental adjustment theory, which covers the parametric adjustment model, conditional adjustment model,conditional adjustment model with parameters and parametric adjustment model with constrains. Applying total least squares (TLS) principle, we deduce the weighted TLS (WTLS) algorithm and the approximated precision of the EIV model. The universal EIV adjustment model and its estimator of WTLS contribute to the integrity of theory of EIV model estimation. The proposed uniform WTLS algorithm is appropriate for programming in software, which can contribute to the geodetic application of the theory of the EIV model estimation.

Land-based GPS Water Vapor Tomography with Projection Plane Algorithm

DING Nan, ZHANG Shubi

2016, 45(8):  895-903.  doi:10.11947/j.AGCS.2016.20160010

Asbtract ( )   HTML   PDF (3588KB) ( )  

References | Related Articles | Metrics

Water vapor tomography is of crucial theoretical importance to and widely applied in meteorology and climatology, for instance, extreme weather forecasting and now casting, numerical weather prediction and climate change study. Conventional water vapor tomography strategy for calculating equation coefficient needs extensive calculation. To solve this problem, projection plane algorithm is developed for improving the speed of calculation and the accuracy of inversion. The GPS signal data used in this article comes from Hong Kong SatRef. The result, which is compared to the traditional algorithm, indicated that new algorithm reduces the computing time greatly and is not affected by size of tomography area and there is consistency in the results of tomographic inversion and radiosonde.

Orbital List Ephemerides Design of LEO Navigation Augmentation Satellite

FANG Shanchuan, DU Lan, ZHOU Peiyuan, LU Yu, ZHANG Zhongkai, LIU Zejun

2016, 45(8):  904-910.  doi:10.11947/j.AGCS.2016.20160091

Asbtract ( )   HTML   PDF (1140KB) ( )  

References | Related Articles | Metrics

A set of reliable LEO (low earth orbit) broadcast ephemerides is required to be designed specifically if LEOs, with current GEOs, are also utilized as navigation augmentation satellites. The classical nine state parameters-based GLONASS-type broadcast ephemerides model can only represent precisely the 30-minute orbital motions of the medium and high earth orbiters. To directly deal with LEOs, a modified 21-parameter broadcast ephemerides model is proposed. First, the short-term variations of the main perturbation forces of LEOs are analyzed. Then a set of simple quadratic polynomials and harmonic functions is adopted to compensate mathematically atmospheric drag perturbation and other effects. A thoroughly simulation for the LEOs of altitude 500~1200 km is given to demonstrate the impact of the numbers of ephemerides parameters, the length of the fitting arcs and the sample rates on the fitting precision. The results of 20-minute fitting arc (approximately 1/5 of orbital period) show that the average RMS of the fitting user range error (FURE) is less than 0.05 m for LEOs higher than 700 km and within 0.03 m for LEOs of altitude 1000 km.

Bias Estimations for Ill-posed Problem of Celestial Positioning Using the Sun and Precision Analysis

ZHAN Yinhu, ZHENG Yong, ZHANG Chao

2016, 45(8):  911-918.  doi:10.11947/j.AGCS.2016.20150525

Asbtract ( )   HTML   PDF (7867KB) ( )  

References | Related Articles | Metrics

Lunar/Mars rovers own sun sensors for navigation, however, long-time tracking for the sun impacts on the real-time activity of navigation. Absolute positioning method by observing the sun with a super short tracking period such as 1 or 2 minutes is researched in this paper. Linear least squares model of altitude positioning method is deduced, and the ill-posed problem of celestial positioning using the sun is brought out for the first time. Singular value decomposition method is used to diagnose the ill-posed problem, and different bias estimations are employed and compared by simulative calculations. Results of the calculations indicate the superiority of bias estimations which can effectively improve initial values. However, bias estimations are greatly impacted by initial values, because the initial values converge at a line which passes by the real value and is vertical relative to the orientation of the sun. The research of this paper is of some value to application.

Accuracy Evaluation of GPS Broadcast Inter-signal Correction (ISC) Parameters and Their Impacts on GPS Standard Positioning

WANG Ningbo, YUAN Yunbin, ZHANG Baocheng, LI Zishen

2016, 45(8):  919-928.  doi:10.11947/j.AGCS.2016.20150554

Asbtract ( )   HTML   PDF (1506KB) ( )  

References | Related Articles | Metrics

With the introducing of GPS (Global Positioning System) Block ⅡR-M satellites in 2005, a new civil signal (L2C) was transmitted on L2 frequency, and two new signals (L5I and L5Q) on a new frequency (L5) were also introduced as standard signals with Block ⅡF satellites beginning in 2010. In addition to the timing group delay (TGD) parameter contained in the legacy navigation (LNAV) message, four additional inter-signal correction (ISC) parameters are introduced in the new civil navigation (CNAV) message to provide corrections for L1C/A, L2C and L5 signals with respect to L1P(Y) signal. In this study, the ISC correction models are first developed for GPS single-and dual-frequency navigation users. Thereafter ISCs are validated with the differential code bias (DCB) products of different organizations, and several standard point positioning (SPP) schemes are also carried out to analyze the impact of ISCs on GPS standard positioning. The results indicate that the precision of broadcast ISC_C/A is about 0.2 ns, and those of TGD, ISC_L2C and ISC_L5Q are about 0.5 ns. The positioning accuracy of the SPP solution based on GPS L2C signals applying ISC corrections improves 30.6% and that based on L1C/A and L2C ionosphere-free combination improves 12.2% at 12 multi-GNSS experiment (MGEX) stations during day of year (DOY) 300-310 in 2014, compared to the solutions without the consideration of ISCs. For GPS dual-frequency users, the broadcast ISCs enable a level of accuracy that is competitive with ionosphere-free combination of the present L1P(Y) and L2P(Y) signals.

An Accurate Method for the BDS Receiver DCB Estimation in a Regional Network

LI Xin, GUO Jiming, ZHOU Lü, QIN Fachao

2016, 45(8):  929-934.  doi:10.11947/j.AGCS.2016.20160044

Asbtract ( )   HTML   PDF (1060KB) ( )  

References | Related Articles | Metrics

An accurate approach for receiver differential code biases (DCB) estimation is proposed with the BDS data obtained from a regional tracking network. In contrast to the conventional methods for BDS receiver DCB estimation, the proposed method does not require a complicated ionosphere model, as long as one reference station receiver DCB is known. The main idea for this method is that the ionosphere delay is highly dependent on the geometric ranges between the BDS satellite and the receiver normally. Therefore, the non-reference station receivers DCBs in this regional area can be estimated using single difference (SD) with reference stations. The numerical results show that the RMS of these estimated BDS receivers DCBs errors over 30 days are about 0.3 ns. Additionally, after deduction of these estimated receivers DCBs and knowing satellites DCBs, the extractive diurnal VTEC showed a good agreement with the diurnal VTEC gained from the GIM interpolation, indicating the reliability of the estimated receivers DCBs.

The Neutrosophic Set and Quantum-behaved Particle Swarm Optimization Algorithm of Side Scan Sonar Image Segmentation

ZHAO Jianhu, WANG Xiao, ZHANG Hongmei, HU Jun, JIAN Xiaomin

2016, 45(8):  935-942.  doi:10.11947/j.AGCS.2016.20150555

Asbtract ( )   HTML   PDF (4704KB) ( )  

References | Related Articles | Metrics

Due to the problem of the existing image segmentation methods applied in side scan sonar (SSS) image often suffered from low efficiency or low accuracy, this paper proposed a novel SSS image thresholding segmentation method based on neutrosophic set (NS) and quantum-behaved particle swarm optimization (QPSO) algorithm. Firstly, the image gray co-occurrence matrix is constructed in NS domain, the fine texture of SSS image is expressed, and this can improve the accuracy of SSS image segmentation. Then, based on the two-dimensional maximum entropy theory, the optimal two-dimensional segmentation threshold vector is quickly and accurately obtained by QPSO algorithm, and this can improve the efficiency and accuracy of SSS image segmentation. Finally, the accurate and high efficient target segmentation of SSS image with high noises is realized. The effectiveness of the algorithm is verified by segmenting SSS image containing different targets.

The Calibration Model and Simulation Analysis of Circular Scanning Airborne Laser Bathymetry System

SHEN Erhua, ZHANG Yongsheng, LI Kai

2016, 45(8):  943-951.  doi:10.11947/j.AGCS.2016.20150532

Asbtract ( )   HTML   PDF (3725KB) ( )  

References | Related Articles | Metrics

To improve the positioning accuracy of circular scanning airborne laser bathymetry system, a calibration method is presented in this paper. When the laser points are collected by the bathymetry system on the level area, they should be on the same plane. However, they are not coplanar because of systematic error and random error. So we try to fit the points to a plane, which may help to adjust the errors and then correct the point location.Firstly, the circular scanning airborne laser bathymetry positioning model is derived in the simple mode. The intersection of laser line and sea surface is simulated depending on the mathematical principles of line and plane intersection. Combined with the direction vector of laser line in the water got by the refraction principle, the sea floor plane mathematical equation is used to compute the location of the laser points. Then, the parameter weighted least squares adjustment model is derived with the prior variance introduced, which lays the foundation for the following computing of calibration model. Finally, the calibration adjustment mathematic model and the detailed computing process are derived. The simulation computing and analysis for the calibration process is presented, and some meaningful conclusions for the calibration are achieved.

Shallow Water Bathymetry through Two-medium Photogrammetry Using High Resolution Satellite Imagery

CAO Bincai, QIU Zhenge, ZHU Shulong, TU Xinru, CAO Fang, CAO Bin

2016, 45(8):  952-963.  doi:10.11947/j.AGCS.2016.20150583

Asbtract ( )   HTML   PDF (18567KB) ( )  

References | Related Articles | Metrics

This paper develops an automated shallow water bathymetry procedure based on two-medium photogrammetry using high resolution satellite multispectral imagery. In this method, near-infrared band were used for sunglint elimination and rational function model (RFM) was applied for raw DEM generation. By extracting the water-land edge and interpolating edge elevation, water surface position could be determined. An approximation refraction correction model, in which all homonymy lights were regarded as intersect to the same observed point, was adopted to correct the vertical offsets. Experimental results indicate that DEM accuracy of satellite two-medium photogrammetry is better than 20% of the average depth under the circumstance of relatively calm water and rich bottom texture.

Hyperspectral Image Land Cover Classification Algorithm Based on Spatial-spectral Coordination Embedding

HUANG Hong, ZHENG Xinlei

2016, 45(8):  964-972.  doi:10.11947/j.AGCS.2016.20150654

Asbtract ( )   HTML   PDF (1909KB) ( )  

References | Related Articles | Metrics

Aiming at the problem that in hyperspectral image land cover classification, the traditional classification methods just apply the spectral information while they ignore the relationship between the spatial neighbors, a new dimensionality algorithm called spatial-spectral coordination embedding (SSCE) and a new classifier called spatial-spectral coordination nearest neighbor (SSCNN) were proposed in this paper. Firstly, the proposed method defines a spatial-spectral coordination distance and the distance is applied to the neighbor selection and low-dimensional embedding. Then, it constructs a spatial-spectral neighborhood graph to maintain the manifold structure of the data set, and enhances the aggregation of data through raising weight of the spatial neighbor points to extract the discriminant features. Finally, it uses the SSCNN to classify the reduced dimensional data. Experimental results using PaviaU and Salinas data set show that the proposed method can effectively improve ground objects classification accuracy comparing with traditional spectral classification methods.

Classification of Land-use Based on Remote Sensing Image Texture Features with Multi-scales and Cardinal Direction Inspired by Domain Knowledge

LAN Zeying, LIU Yang

2016, 45(8):  973-982.  doi:10.11947/j.AGCS.2016.20150624

Asbtract ( )   HTML   PDF (10773KB) ( )  

References | Related Articles | Metrics

Texture features based on grey level co-occurrence matrix (GLCM) are effective for image analysis, and this paper proposed a new method to construct GLCM with multi-scales and cardinal direction factors inspired by domain knowledge, in order to improve the performance of texture features and solve the uncertainty problems in image classification of land-use. By simulating the process of human visual interpretation, an integrated computation pattern of GIS and RS data were performed. Firstly, on the basis of image registration, some classic GIS spatial data mining algorithms were employed to asymptotically extract domain morphological knowledge; Next, under the responding mechanism derived from correlated analysis, an algorithm for establishing GLCM multi-scale windows that can match categories one by one, an algorithm for determining GLCM weighted cardinal direction windows that can describe observation orientation were designed based on relevant morphology indexes. Experimental results indicate that, there is a strong correlation between domain morphological knowledge and GLCM construction factors, meanwhile, with lower computational complexity, the new method can extract stable texture features to describe actual spatial meanings of complex objects, thereby improve the image classification accuracy of land-use.

Clutter-free Visualization of Large Point Symbols at Multiple Scales by Offset Quadtrees

ZHANG Xiang, WANG Shaodong, WANG Yuxia

2016, 45(8):  983-991.  doi:10.11947/j.AGCS.2016.20150446

Asbtract ( )   HTML   PDF (4670KB) ( )  

References | Related Articles | Metrics

To address the cartographic problems in map mash-up applications in the Web 2.0 context, this paper studies a clutter-free technique for visualizing large symbols on Web maps. Basically, a quadtree is used to select one symbol in each grid cell at each zoom level. To resolve the symbol overlaps between neighboring quad-grids, multiple offsets are applied to the quadtree and a voting strategy is used to compute the significant level of symbols for their selection at multiple scales. The method is able to resolve spatial conflicts without explicit conflict detection, thus enabling a highly efficient processing. Also the resulting map forms a visual hierarchy of semantic importance. We discuss issues such as the relative importance, symbol-to-grid size ratio, and effective offset schemes, and propose two extensions to make better use of the free space available on the map. Experiments were carried out to validate the technique,which demonstrates its robustness and efficiency (a non-optimal implementation leads to a sub-second processing for datasets of a 10⁵ magnitude).

Estimation of GNSS Multiscale Strain Field and Detection of Regional Crustal Deformation

XU Keke, WU Jicang

2016, 45(8):  992-1000.  doi:10.11947/j.AGCS.2016.20150588

Asbtract ( )   HTML   PDF (8117KB) ( )  

References | Related Articles | Metrics

Using GNSS data,the estimation model for GNSS multiscale strain field was established based on spherical wavelet. The key technologies for wavelet center location, wavelet scale choices and regularization parameter calculation were discussed in detail. For further testing the correctness of the model, the simulated data in locked fault areas was generated according to negative dislocation theory. With spherical wavelet model, the strain field in locked strike-slip fault areas was estimated,and the results agreed well with the characteristics of actual crustal deformation. Meanwhile, the experiments on crustal deformation anomaly detection with multiscale strain field were completed. The results showed that the small fault deformation of 50 km appeared obviously in the small scale(8th scale) stain field, but there wasn't signals in the large scale (4 to 7 scale). The large fault deformation of 150 km only showed a part of information in the small scale (8th scale) stain field, but showed more completely and clearly in the large scale(4 to 7 scale).So it's concluded that crustal deformation of different spatial coverage scope embody in the different scales strain field, and the small scale strain field have the ability to detect regional deformation anomaly.

Classification and Filtering of Constrained Delaunay Triangulation for Automated Building Aggregation

GUO Peipei, LI Chengming, YIN Yong

2016, 45(8):  1001-1007.  doi:10.11947/j.AGCS.2016.20150587

Asbtract ( )   HTML   PDF (1829KB) ( )  

References | Related Articles | Metrics

Building aggregation is an important part of research on large scale map generalization. A triangulation based approach is proposed from the perspective of shape features, six measure parameters of triangles in a constrained Delaunay triangulation are proposed. First of all, use the six measure parameters to determine which triangles are retained and which are erased. Then, the contours of retained triangles, as bridge areas between buildings, are automatically identified and right angle processed. And then, the buildings are aggregated with right angle feature retained by merging the bridge areas with connecting buildings. Finally, the approach is verified by being carried out on actual data. Experimental result shows that it is efficient and practical.

Research on Personalized Map Cognition Mechanism

ZHENG Shulei

2016, 45(8):  1008-1008.  doi:10.11947/j.AGCS.2016.20160290

Asbtract ( )   HTML   PDF (698KB) ( )  

Related Articles | Metrics