Table of Content

20 December 2017, Volume 46 Issue 12

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Comparison and Analysis of Three GPS+BDS PPP Models

ZANG Nan, LI Bofeng, SHEN Yunzhong

2017, 46(12):  1929-1938.  doi:10.11947/j.AGCS.2017.20170111

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In general,ionosphere-free model and uncombined model are applied for GNSS precise point positioning (PPP).This paper detailed analyzes the correlation of different parameters of each model,and deducevarious PPP functional model by means of parameterization methods.And uncombined PPP with ionospheric parameter constrains i.e.ionosphere-weighted model can fasten PPP convergence effectively.This paper takes advantage of GPS-only and GPS and BDS combination dataset as example for positioning in different PPP models.In the perspective of positioning accuracy and convergence time,positioning performance are detailed analyzed in both static PPP and simulated dynamic PPP modes.The results demonstrate that GPS-only has the similar accuracy with GPS+BDS combination,and both ionosphere-free model and uncombined model static PPP can achieve the positioning accuracy of millimeter to centimeter level,while the horizontal positioning accuracy of dynamic PPP is superior to 3 cm and the vertical positioning accuracy is superior to 5 cm.In terms of convergence time,ionosphere-free model is superior to uncombined model,and the convergence time of ionosphere-weighted model is the shortest.Compared to the ionosphere-free model,the ionosphere-weighted model can decrease about 15% convergence time,while it can decrease about 34% convergence time compared to the uncombined model in the dynamic positioning.

Analysis and Validation of ZY-3 02 Satellite Laser Altimetry Data

LI Guoyuan, TANG Xinming

2017, 46(12):  1939-1949.  doi:10.11947/j.AGCS.2017.20170174

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ZY-3 02 satellite loaded with Chinese first earth observing satellite laser altimeter,and has been launched successfully on 30th May,2016. In this paper,the theoretical accuracy of the laser altimeter is analyzed,and several experimental areas are used to verify the actual accuracy. At the same time,the application of the laser altimetry data in the field of space-borne photogrammetry is tested. The laser altimetry theoretical accuracy of ZY-3 02 satellite in the flat area (slope less than 2 degrees) is about 0.85 m and 14.2 m in the elevation and planimetry direction,respectively. The effective laser altimetry data account for about 23.89%,and near the calibration field the elevation accuracy is 0.89 m,and planimetry accuracy is about 14.76 m. Moreover,the verified elevation accuracy is 1.09 m in the North China by high precision DSM terrain data,and laser footprint points accuracy on the surface of the Bohai inland sea is about 0.47 m. When the laser foot print point is used as elevation control point,the elevation accuracy of the ZY-3 02 satellite stereo images in Shaanxi Weinan can be increased from 11.54 m to 1.90 m without GCPs. Although ZY3-02 satellite laser altimeter is just a test,the results proved that the domestic satellite laser altimetry data can effectively improve the stereo images without GCPs,which will be valuable in the global mapping project. It is suggest that operational laser altimeter equip on the next satellite of ZY-3 serials.

3D Laser Scanning Assisted by Ordinary Plane Mirror for Non-direct Viewing Area

ZHANG Fan, HUANG Yin, HUANG Xianfeng, XU Siqi

2017, 46(12):  1950-1958.  doi:10.11947/j.AGCS.2017.20170052

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Terrestrial 3D laser scanning is one of principal methods to get the geometric information of object surface,and the integrity of the scanned object is a basic requirement in data acquisition. In order to solve the missing point cloud problem due to the scanning dead angle caused by confined working space,this paper proposes a method using ordinary plane mirror to obtain laser scanning data for non-direct viewing area according to the plane mirror reflection principle,analyzes the influence mechanism of the ordinary plane mirror on the propagation path and distance of laser beam,deduces the coordinate equation of the object point corresponding to the image point reflected by ordinary plane mirror in laser scanning. Given the laser scanning characteristic,this paper introduces a mirror reflection system included target balls and ordinary plane mirror,and expounds the system construction,system calibration and constructing method of system coordinate system. The feasibility and precision of the method are verified by experiments.

A Residential Area Extraction Method for High Resolution Remote Sensing Imagery by Using Visual Saliency and Perceptual Organization

CHEN Yixiang, QIN Kun, ZHANG Ye, YUAN Yuan

2017, 46(12):  1959-1968.  doi:10.11947/j.AGCS.2017.20170176

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Inspired by human visual cognitive mechanism,a method of residential area extraction from high-resolution remote sensing images was proposed based on visual saliency and perceptual organization. Firstly,the data field theory of cognitive physics was introduced to model the visual saliency and the candidate residential areas were produced by adaptive thresholding. Then,the exact residential areas were obtained and refined by perceptual organization based on the high-frequency features of multi-scale wavelet transform. Finally,the validity of the proposed method was verified by experiments conducted on ZY-3 and Quickbird image data sets.

Unsupervised Remote Sensing Domain Adaptation Method with Adversarial Network and Auxiliary Task

XU Suhui, MU Xiaodong, ZHANG Xiongmei, CHAI Dong

2017, 46(12):  1969-1977.  doi:10.11947/j.AGCS.2017.20170291

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An important prerequisite when annotating the remote sensing images by machine learning is that there are enough training samples for training, but labeling the samples is very time-consuming. In this paper, we solve the problem of unsupervised learning with small sample size in remote sensing image scene classification by domain adaptation method. A new domain adaptation framework is proposed which combines adversarial network and auxiliary task. Firstly, a novel remote sensing scene classification framework is established based on deep convolution neural networks. Secondly, a domain classifier is added to the network, in order to learn the domain-invariant features. The gradient direction of the domain loss is opposite to the label loss during the back propagation, which makes the domain predictor failed to distinguish the sample's domain. Lastly, we introduce an auxiliary task for the network, which augments the training samples and improves the generalization ability of the network. The experiments demonstrate better results in unsupervised classification with small sample sizes of remote sensing images compared to the baseline unsupervised domain adaptation approaches.

Road Extraction from High-spatial-resolution Remote Sensing Image by Combining GVF Snake with Salient Features

WANG Fengping, WANG Weixing, XUE Baiyu, CAO Ting, GAO Ting

2017, 46(12):  1978-1985.  doi:10.11947/j.AGCS.2017.20170393

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The road information in the high-spatial-resolution remote sensing image is of great significance for updating the GIS database. Through analyzing the road features shown in the remote sensing image, this paper presents a road detection method based on salient features and gradient vector flow (GVF) Snake. According to the visual cognition theory, the road geometric and radiation features are viewed as salient features in this paper. First, the saliency map is calculated by fusing the color-based and structure-based contrasts, the maximum saliency value is regarded as the seeds of the GVF Snake. Then, a region-growing algorithm is applied to compute the initial boundaries, the energy function of the GVF Snake is minimized by iterative solution of the gradient vector flow model to get the final road information.Experimental results show that the proposed method could enhance the computational efficiency and has good detection accuracy.

Large Collection Satellite Images Color Normalization Algorithm Based on Tone Reference Map

CUI Hao, ZHANG Li, AI Haibin, XU Biao, WANG Zhonghui

2017, 46(12):  1986-1997.  doi:10.11947/j.AGCS.2017.20170402

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For a large collection of satellite images,because of the differences in season,light,atmospheric conditions and so on,adjacent satellite images may have different color and there will be obviously "seam-line" in mosaic satellite image.In this paper,a method of satellite image color normalization was proposed,it was implemented to correct the color of image automatically based on better color low resolution satellite imagery which covered the mapping area.We selected a large collection and long time interval GF-1 satellite images as experiment data,results show that the mosaic image have a good visual effect,the color transition of two images smoothly,statistical indicators of overlap area obviously improved,all of those verified the validity and reliability of the algorithm.

A Fresh Phase Unwrapping Method Based on Modified Embedded Cubature Kalman Filter

DAI Gaoxing, XIE Xianming

2017, 46(12):  1998-2005.  doi:10.11947/j.AGCS.2017.20160665

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A phase unwrapping algorithm is proposed that based on modified embedded cubature Kalman filter for interferometric fringes.The algorithm is the result through combining an embedded cubature Kalman filter modified by a Levenberg-Marquardt method,a robust phase gradient estimator based on amended matrix pencil model,and a quantization path-following strategy.This method can accurately estimate unambiguous unwrapped phase of interferometric fringes by applying the modified embedded cubature Kalman filter to perform phase unwrapping and noise suppress simultaneously along the path routed by the quantization path-following strategy,which is beneficial to simplify the complexity and the difficulty of pre-filtering procedure followed by phase unwrapping procedure,and even can remove the pre-filtering procedure.Results obtained with synthetic data and real data show more acceptable solutions with the proposed method,compared with some of the most used algorithms.

Visualisation and Analysis of Non-spatial Hierarchical Data of Gosper Map

XIN Rui, AI Tinghua, HE Yakun

2017, 46(12):  2006-2015.  doi:10.11947/j.AGCS.2017.20160596

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This study focuses on spatial metaphor expression and analysis of hierarchy data with the help of map metaphor. We use classic cartographic methods synthetically to process the non-spatial data to realize the spatialization. This process makes abstract data concrete which can reduce cognitive load. In addition,it expands the extension of cartography. In terms of specific methods,we use the landscape metaphor to reflect data feature,and introduce LOD and Cartogram into map metaphor which is suitable for hierarchy data's structural characteristics. Comprehensive usage of above methods help highlight features of each layer of data and analyze data characteristics through the map. At last the validity of this method is verified by the real file hierarchy data. We conduct experiments to analyze file number distribution,large file location and file depth. The results show that our method can effectively express the hierarchical data and support some map analysis and data mining.

A Method of Speed-preserving Trajectory Simplification

YANG Min, CHEN Yuanyuan, JIN Cheng, CHENG Qian

2017, 46(12):  2016-2023.  doi:10.11947/j.AGCS.2017.20170023

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Trajectory simplification plays an important role in trajectory data storage,transmission,temporal-spatial analysis and visualization.Traditional simplification methods,such as Douglas-Peucker algorithm,concern the geometric information while ignore the temporal information,which may result in loss of implied mobility features in the original trajectory.Aiming at minimize speed error in the trajectory simplification transformation,this paper presents a new method based on hierarchical clustering and regionalization operations.First,the line segments of the original trajectory are clustered at different levels based on the similarity of speed measure.With the support of the hierarchical clusters,the original trajectory is then divided into a series of segments.For each segment,the maximum synchronized Euclidean distance from the points to the segment line connecting two end points is no larger than the predefined threshold value.Finally,the simplified results is outputted by organizing the end points of each trajectory segments.Real life data was used to verity the effectiveness of the proposed method,and results of comparing with other existing methods showed that our method performs better in speed preserving.

A Space-time Path Supported Estimation Approach for Vehicles' Fuel-consumption and Emissions

TANG Luliang, KAN Zihan, DUAN Qian, LI Qingquan

2017, 46(12):  2024-2031.  doi:10.11947/j.AGCS.2017.20160439

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The fuel-consumption and emissions from transportation present severe challenges to the human environment. This article proposes a novel approach of space-time path supported estimation for vehicles' fuel-consumption and emissions. In the proposed approach,space-time paths of vehicles are built under space-time integrated 3-dimensions coordinate firstly and mobile activities (MA) and stationary activities (SA) are extracted from these space-time paths. Then the approach estimates the fuel-consumption and emissions from each Space-Time Path Segment (STPS) and the moving parameters with COPERT model. Finally this article presents an N-Dimensional model for visualizing the moving characteristics,fuel-consumption and emissions of each STPS in an integrated frame. In the case study,fuel-consumption and emissions of a single vehicle and an area of road network are estimated and analyzed using GPS trace data. The results show that the space-time path supported approach is superior to the traditional average speed based approach in the aspects of precision and visualization. The proposed fuel-consumption and emissions estimating approach is effective in energy and emissions information acquisition.

Measuring Traffic Correlations in Urban Road System Using Word Embedding Model

LIU Kang, QIU Peiyuan, LIU Xiliang, ZHANG Hengcai, WANG Shaohua, LU Feng

2017, 46(12):  2032-2040.  doi:10.11947/j.AGCS.2017.20170166

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Good characterization of road traffic correlations among urban roads can help improve the traffic-related applications,such as traffic interpolation and short-term traffic forecasting. Previous studies model the traffic correlations between two roads by their spatial or topological distances. However,the distance-based methods neglect the spatio-temporal heterogeneity of traffic influence among roads. In this paper,we integrate GPS-enabled vehicle operating travel routes and word embedding techniques in Natural Language Processing (NLP) domain to quantify traffic correlations of road segments in different time intervals. Firstly,the corresponding relationships between transportation elements (i.e.,road segments,travel routes) and NLP terms (i.e.,words,documents) are established. Secondly,the real-valued vectors of road segments are trained from massive travel routes using a word-embedding model called "Word2Vec". Thirdly,the traffic correlation between two roads is measured by the cosine similarity of their vectors. Finally,the results are evaluated using real traffic condition data. Results of a case study using a large-scale taxi trajectory dataset in Beijing show that:①road segments that have stronger traffic correlations are also more similar in their traffic conditions measured by roads' average travel speeds,proving that our approach is capable of quantifying road segment traffic correlations and detecting their spatial heterogeneity;②road segments' traffic correlations are stronger on workday rush hours and holidays than on weekends and workday non-rush hours,proving that our approach is capable of detecting temporal variations. Our approach and analysis provide methodological and theoretical basis for transportation related applications using NLP and machine learning models.

Data Processing and Signal Analysis for Multi-data Series of Crustal Deformation on Global and Regional Scales

LI Weiwei

2017, 46(12):  2041-2041.  doi:10.11947/j.AGCS.2017.20170152

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Research on Marine Celestial Navigation Based on Fisheye Camera

LI Chonghui

2017, 46(12):  2042-2042.  doi:10.11947/j.AGCS.2017.20170154

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Precise Co-located Baseline Solution and GNSS Data Processing for the Base Stations of CMONOC

MA Xiaping

2017, 46(12):  2043-2043.  doi:10.11947/j.AGCS.2017.20170179

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In-memory Distributed Computing Based Approximate Query Processing on Spatial Data

QIU A'gen

2017, 46(12):  2044-2044.  doi:10.11947/j.AGCS.2017.20170602

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Study on Quality Evaluation and 3D Rapid Reconstruction for Terrestrial Laser Scanning Point Cloud

XUAN Wei

2017, 46(12):  2045-2045.  doi:10.11947/j.AGCS.2017.20170407

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