Table of Content

20 December 2016, Volume 45 Issue 12

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A GPS Satellite Clock Offset Prediction Method Based on Fitting Clock Offset Rates Data

WANG Fuhong, XIA Boyang, GONG Xuewen

2016, 45(12):  1387-1395.  doi:10.11947/j.AGCS.2016.20150480

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It is proposed that a satellite atomic clock offset prediction method based on fitting and modeling clock offset rates data. This method builds quadratic model or linear model combined with periodic terms to fit the time series of clock offset rates, and computes the model coefficients of trend with the best estimation. The clock offset precisely estimated at the initial prediction epoch is directly adopted to calculate the model coefficient of constant. The clock offsets in the rapid ephemeris (IGR) provided by IGS are used as modeling data sets to perform certain experiments for different types of GPS satellite clocks. The results show that the clock prediction accuracies of the proposed method for 3, 6, 12 and 24 h achieve 0.43, 0.58, 0.90 and 1.47 ns respectively, which outperform the traditional prediction method based on fitting original clock offsets by 69.3%, 61.8%, 50.5% and 37.2%. Compared with the IGU real-time clock products provided by IGS, the prediction accuracies of the new method have improved about 15.7%, 23.7%, 27.4% and 34.4% respectively.

Seamless Linear Regression and Prediction Model

WANG Miaomiao, LI Bofeng

2016, 45(12):  1396-1405.  doi:10.11947/j.AGCS.2016.20160263

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The regression model was traditionally established by using the least squares (LS) method where the errors of independent variables were ignored. Although the weighted total least squares (TLS) method that captures errors of both dependent and independent variables was extensively studied for regression analysis in recent years, it still neglects the errors of independent variables when predicting the corresponding dependent variables.This paper puts forward a seamless linear regression and prediction model which estimates regression parameters and predicts dependent variables simultaneously by considering the errors of all variables.In the seamless model, the errors of independent variables in the prediction model are predicted and corrected to improve the prediction accuracy.The several existing regression models are theoretically proved to be the special cases of the proposed seamless model. The experimental results show that the proposed seamless model outperforms the other existing models in the sense of prediction accuracy, especially when the error correlation of variables is significant.

Swarm Satellite Antenna Phase Center Correction and Its Influence on the Precision Orbit Determination

TIAN Yingguo, HAO Jinming

2016, 45(12):  1406-1412.  doi:10.11947/j.AGCS.2016.20160132

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Receiver antenna phase center bias is a source of error must be considered in precise orbit determination using GPS. And PCV generally need multi-day observations data for joint estimation, so the estimation methods and its efficiency are particularly important. For the traditional PCV estimation method imperfect, such as the low computational efficiency, need to store days of normal equations and a priori information, this paper proposes an improved PCV synthesis method. By recursive way, the method doesn't need to store multi-day normal equations and the priori information about orbit, provide timely information PCV, then improve the efficiency of obtaining the PCV value, and provides a new way to achieve the Swarm satellite PCV solution. By the Swarm satellite precise orbit determination (POD), the result shows that the rapid PCV synthesis method can improve the efficiency of PCV synthesis, reducing the need for storage space. By comparing with external precision orbit, the result show that after the PCV correction, radial, tangential and normal precision of Swarm satellite orbit is improved, especially the normal precision most obviously, the average of about 23.3 mm; after the PCV correction, Swarm satellite orbit precision of all directions was superior to 2 cm.

Method of Monitoring Urban Area Deformation Based on Differential TomoSAR

WANG Aichun, XIANG Maosheng, WANG Bingnan

2016, 45(12):  1413-1422.  doi:10.11947/j.AGCS.2016.20160113

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While the use of differential TomoSAR based on compressive sensing (CS) makes it possible to solve the layover problem and reconstruct the deformation information of an observed urban area scene acquired by moderate-high resolution SAR satellite, the performance of the reconstruction decreases for a sparse and structural observed scene due to ignoring the structural characteristics of the observed scene. To deal with this issue, the method for differential SAR tomography based on Khatri-Rao subspace and block compressive sensing (KRS-BCS) is proposed. The proposed method changes the reconstruction of the sparse and structural observed scene into a BCS problem under Khatri-Rao subspace, using the structure information of the observed scene and Khatri-Rao product property of the reconstructed observation matrix for differential TomoSAR, such that the KRS-BCS problem is efficiently solved with a block sparse l₁/l₂ norm optimization signal model, and the performance of resolution capability and reconstruction estimation is compared and analyzed qualitatively and quantitatively by the theoretical analysis and the simulation experiments, all of the results show the propose KRS-BCS method practicably overcomes the problems of CS method, as well as, quite maintains the high resolution characteristics, effectively reduces the probability of false scattering target and greatly improves the reconstruction accurate of scattering point. Finally, the application is taking the urban area of the Mobara(in Chiba, Japan) as the test area and using 34 ENVISAT-ASAR images, the accuracy is verifying with the reference deformations derived from first level point data and GPS tracking data, the results show the trend is consistent and the overall deviation is small between reconstruction deformations of the propose KRS-BCS method and the reference deformations, and the accuracy is high in the estimation of the urban area deformation.

Image Dodging Algorithm for GF-1 Satellite WFV Imagery

HAN Jie, XIE Yong

2016, 45(12):  1423-1433.  doi:10.11947/j.AGCS.2016.20160248

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Image dodging method is one of the important processes that determines whether the mosaicking image can be used for remote sensing quantitative application. GF-1 satellite is the first satellite in CHEOS (Chinese high-resolution earth observation system). WFV multispectral sensor is one of the instruments onboard GF-1 satellite which consist of four cameras to mosaic imaging. According to the characteristics of WFV sensor, this paper proposes an image dodging algorithm based on cross/inter-radiometric calibration method. First, the traditional cross calibration method is applied to obtain the calibration coefficients of one WFV camera. Then statistical analysis and simulation methods are adopted to build the correlation models of DN and TOA (top of atmosphere) radiances between adjacent cameras. The proposed method can not only accomplish the radiation performance transfer, but also can fulfill the image dodging. The experimental results show the cross/inter-radiometric calibration coefficients in this paper can effectively eliminate the radiation inconsistency problem of the adjacent camera image which realizes the image dodging. So our proposed dodging method can provide an important reference for other similar sensor in future.

Spaceborne SAR Image Geometric Rectification Method without Ground Control Points Using Orbit Parameters Modulation

CHEN Jiwei, ZENG Qiming, JIAO Jian, YE Fawang, ZHU Lijiang

2016, 45(12):  1434-1440.  doi:10.11947/j.AGCS.2016.20160182

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When using the Range-Doppler model for SAR image geometric correction, the error of satellite orbit, imaging parameter and DEM elevation will affect the geometric correction accuracy. A new geometric rectification method has been presented for spaceborne SAR image. First, polynomial was used for parameterizing SAR orbit. Then orbit parameters were corrected by control points that acquired by matching of simulated SAR image and real SAR image. Finally, the precise geometric rectification using corrected parameters was accomplished. The presented method can be applied for SAR image geometric rectification where the ground control points are difficult to be acquired. It has higher precision compared to the geometric rectification based on image simulation and polynomial correction. The Radarsat-2 image was used in experiments, and the ground control points measured by GPS validated the proposed approach.

A Modified FCM Classifier Constrained by Conditional Random Field Model for Remote Sensing Imagery

WANG Shaoyu, JIAO Hongzan, ZHONG Yanfei

2016, 45(12):  1441-1447.  doi:10.11947/j.AGCS.2016.20150621

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Remote sensing imagery has abundant spatial correlation information, but traditional pixel-based clustering algorithms don't take the spatial information into account, therefore the results are often not good. To this issue, a modified FCM classifier constrained by conditional random field model is proposed. Adjacent pixels' priori classified information will have a constraint on the classification of the center pixel, thus extracting spatial correlation information. Spectral information and spatial correlation information are considered at the same time when clustering based on second order conditional random field. What's more, the global optimal inference of pixel's classified posterior probability can be get using loopy belief propagation. The experiment shows that the proposed algorithm can effectively maintain the shape feature of the object, and the classification accuracy is higher than traditional algorithms.

Block-adjustment and Accuracy Validation for GF4 Patch-images Based on RFM

PI Yingdong, YANG Bo, LI Xin

2016, 45(12):  1448-1454.  doi:10.11947/j.AGCS.2016.20160262

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It is analysed that the geometric characters of specific patch-imaging mode of GF4 which is the first geostationary orbit optical remote sensing satellite of China. And a block adjustment method using average elevation is proposed directing at the specific geometric character that the base to height ratio between images is very small. The method constructs the block adjustment model based on rational function model (RFM) and the proposed block adjustment method is employed on the GF4 patch-images without ground control, which solves the low splicing accuracy situation due to some factors, such as low orbit and attitude measurement accuracy, astronomical refraction and lens distortion etc. At last, in two experiments with GF4 real data, it is verified that the accuracy and effectiveness of the proposed method, and the influence of different imagery errors compensated model is analysed also.

An Adaptive Filtering Method Based on Crowdsourced Big Trace Data

TANG Luliang, YANG Xue, NIU Le, CHANG Le, LI Qingquan

2016, 45(12):  1455-1463.  doi:10.11947/j.AGCS.2016.20160117

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Vehicles' GPS traces collected by crowds have being as a new kind of big data and are widely applied to mine urban geographic information with low-cost, quick-update and rich-informative. However, the growing volume of vehicles' GPS traces has caused difficulties in data processing and their low quality adds uncertainty when information mining. Thus, it is a hot topic to extract high-quality GPS data from the crowdsourced traces based on the expected accuracy. In this paper, we propose an efficient partition-and-filter model to filter trajectories with expected accuracy according to the spatial feature of high-precision GPS data and the error rule of GPS data. First, the proposed partition-and-filter model to partition a trajectory into sub-trajectories based on the constrained distance and angle, which are chosen as the basic unit for the next processing step. Secondly, the proposed method collects high-quality GPS data from each sub-trajectory according to the similarity between GPS tracking points and the reference baselines constructed using random sample consensus algorithm. Experimental results demonstrate that the proposed method can effectively pick up high quality GPS data from crowdsourced trace data sets with the expected accuracy.

A Dynamic Optimization Method of Indoor Fire Evacuation Route Based on Real-time Situation Awareness

DING Yulin, HE Xiaobo, ZHU Qing, LIN Hui, HU Mingyuan

2016, 45(12):  1464-1475.  doi:10.11947/j.AGCS.2016.20160053

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How to provide safe and effective evacuation routes is an important safeguard to correctly guide evacuation and reduce the casualties during the fire situation rapidly evolving in complex indoor environment. The traditional static path finding method is difficult to adjust the path adaptively according to the changing fire situation, which lead to the evacuation decision-making blindness and hysteresis. This paper proposes a dynamic method which can dynamically optimize the indoor evacuation routes based on the real-time situation awareness. According to the real-time perception of fire situation parameters and the changing indoor environment information, the evacuation route is optimized dynamically. The integrated representation of multisource indoor fire monitoring sensor observations oriented fire emergency evacuation is presented at first, real-time fire threat situation information inside building is then extracted from the observation data of multi-source sensors, which is used to constrain the dynamical optimization of the topology of the evacuation route. Finally, the simulation experiments prove that this method can improve the accuracy and efficiency of indoor evacuation routing.

A 3D Annotation Optimal Placement Algorithm for the Point Features in the Small Scale Geographic Scene

ZHOU Xinxin, WU Changbin, SUN Zaihong, DING Yuan, HE Tao

2016, 45(12):  1476-1484.  doi:10.11947/j.AGCS.2016.20160210

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The 3D annotations placement rules of point features in geographic scene are "obscured then not showing" and "obscured then directly showing" normally. The defects of those rules are annotation information lost or large numbers of occlusion, so their universalities are not strong and they are not suitable for the annotation placement of small-scaled geographic scene. This paper summarizes the contents, position and placement methods of 3D annotation and takes the aim at "not loss of annotation information and less annotation obscured as far as possible" of the research problem of the annotation placement of small-scaled geographic scene. The configuration rule of 3D annotation Identifies as "obscured then optimized to display". The designed algorithm based on the perspective transformation matrix, the inverse perspective transformation matrix and the grid algorithm takes the genetic algorithm (GA) whose fitness evaluation function uses the 3D Annotation quality evaluation function as the core to realize the feasible optimal solution of 3D annotations of point features in geographic scene. By the multi-views, multi-platforms contrast experiment, this algorithm is applicable for multi-views 3D annotation placement widely. The 3D annotation effect is better than mainstream GIS platforms (such as SuperMap desktop, ArcScene), which assumes that the algorithm's 3D annotation quality value is relatively increased 144%, 232%. The algorithm fits in with the target configuration.

A Linkage Matching Method for Road and Habitation by Using Urban Skeleton Line Network

LIU Chuang, QIAN Haizhong, WANG Xiao, HE Haiwei, XIE Limin, WANG Chengshun

2016, 45(12):  1485-1494.  doi:10.11947/j.AGCS.2016.20160221

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Obvious data consistency degree is not high in roads or habitation data, often in the presence of large geometric position deviation, which is not conducive to improve the accuracy and efficiency of road or habitation matching. A linkage matching method for road and habitation by using urban skeleton line network is proposed to solve this problem. The linkage matching imitates the human thinking process of searching for target objects by the signal features and spatial correlation when reading maps, regarding matching as a reasoning process of goal feature searching and information association transmitting. Firstly, urban skeleton line network is constructed by constraint Delaunay triangulation network; then, the topological relationship among road, skeleton line, skeleton line mesh, habitation is constructed; last, matching transmission model is established by the topological relationship. According to this matching transmission model, linkage matching is fulfilled, which contains road matching drives habitation matching or habitation matching drives road matching. The advantage of this method is that as long as there is an element of data consistency is good, can drive another element to obtain a very good matching effect, at the same time conform to the human cognitive process.

3D Power Line Reconstruction from Airborne LiDAR Point Cloud

DUAN Minyan

2016, 45(12):  1495-1495.  doi:10.11947/j.AGCS.2016.20160341

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Comprehensive Evaluation and Adaptive Restoration of Remotely Sensed Images

WANG Rongbin

2016, 45(12):  1496-1496.  doi:10.11947/j.AGCS.2016.20160386

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The Road Network Overall Construction Based on Volunteered Geographic Information and ZY-3 Remote Sensing Image

LIU Bo

2016, 45(12):  1497-1497.  doi:10.11947/j.AGCS.2016.20160388

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Research on Key Issues of Sediment Classification for Seabed and Sub-bottom Based on Multi-beam and Sub-bottom Profile Echo Intensity

HE Linbang

2016, 45(12):  1498-1498.  doi:10.11947/j.AGCS.2016.20160466

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