Zhejiang Academy of Surveying and Mapping

Hangzhou, China

Zhejiang Academy of Surveying and Mapping

Hangzhou, China

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Yu Z.,Wuhan University | Li L.,Wuhan University | Qiu J.,Wuhan University | Chen S.,Zhejiang Academy of Surveying and Mapping
Proceedings - 2011 19th International Conference on Geoinformatics, Geoinformatics 2011 | Year: 2011

According to the needs of emergency thematic cartography and the China's existing Specification for the military symbols, the types of situation symbols that may be used in emergency thematic cartography were summed up in this paper. A comprehensive modeling was raised for these situation symbols and it is flexible for emergency thematic cartography. There are four kinds of situation symbols: contour symbol, simple arrow symbols, single arrow symbols and combined arrow symbols in this paper. The position line of the symbols is a Bezier curve or a polyline. The oblique axis parabolic algorithm and the Hermite interpolation algorithm are selected for smoothing the position lines of the symbols. The Douglas-Peucker algorithm is picked out for scattering the position curve. At last, this paper developed a cartographic system based on the national fundamental geographic information, and realized the modeling and drawing of the situation symbols with the cartographic system. © 2011 IEEE.


Wenhua Z.,Zhejiang Academy of Surveying and Mapping
2nd International Conference on Information Science and Engineering, ICISE2010 - Proceedings | Year: 2010

The statistic analysis mothed is used to analyze the region landlside susceptibility in landslide hazard analysis. In the mothod, landslide invetntory and the data of enviromental factors which induce landslides are essential. The Cameron Highlands of Malaysia was selected as the experimental studying area. Based on GIS and the Bivariate statistical analysis mothod, the relationships among landslides and environmental factors were analyzed. Then, Probability Index Model and Distance Evaluation Model were developed. The comparison and assessment of two models show that they have higher prediction precision and universality. The effect of Distance Evaluation Model is better than that of Probability Index Model. © 2010 IEEE.


Fu Z.,Wuhan University | Yang Y.,Wuhan University | Gao X.,Yangtze University | Zhao X.,Wuhan University | And 2 more authors.
Wuhan Daxue Xuebao (Xinxi Kexue Ban)/Geomatics and Information Science of Wuhan University | Year: 2016

Identifying corresponding objects is crucial in the process of heterogeneous road network matching. This paper proposed a road network matching method based on a multiple logistic regression algorithm. First, three dissimilar characteristics integrating both spatial and non-spatial features were used to describe the difference of the corresponding pairs of road objects; the minimum angle of the orientation, the mixed median Hausdorff distance, and semantic discrepancy. Using these three characteristics as variables of multiple logistic regression, we built a basic multiple logistic regression matching model. Samples to train the final road matching model were acquired to obtain matching results by predicting probability of each candidate road matching pair. Experimental results show that this method needs no exact feature weights and thresholds, and can solve the matching result problems stemming from over-reliance on single variable. This method has good adaptability, with higher precision and recall rates. © 2016, Wuhan University. All right reserved.


Wu H.,Chinese Academy of Surveying and Mapping | Zhang Y.,Chinese Academy of Surveying and Mapping | Luo G.,Zhejiang Academy of Surveying and Mapping | Mao W.,Zhejiang Academy of Surveying and Mapping | And 2 more authors.
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2015

Affected by over-exploration of groundwater for a long time, the Hangjiahu Plain in Zhejiang province, southeast of China, has suffering serious ground subsidence during the past several decades. In this paper, we investigate the time series InSAR technique for the generation of subsidence maps over this plain. 25 Radarsat-2 images acquired from Jan 2012 to Nov 2014 are used. The results show that serious subsidence has taken place in the north and southeast of Jiaxing, the east and north of Huzhou, and the north of Hangzhou. Meanwhile some rebound occurs in the east of Jiaxing and the southeast of Huzhou. The results are compared with 35 levelling measurements. The standard deviation of the error between the two data is 3.01mm, which demonstrate that time series InSAR technique has good accuracy for subsidence monitoring. © 2015 SPIE.


Wu H.A.,Chinese Academy of Surveying and Mapping | Zhang Y.H.,Chinese Academy of Surveying and Mapping | Luo G.F.,Zhejiang Academy of Surveying and Mapping | Mao W.H.,Zhejiang Academy of Surveying and Mapping | And 2 more authors.
International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences - ISPRS Archives | Year: 2015

Because of over-exploration of groundwater for a long time, Jiaxing region, northeast of Zhejiang province has suffering serious ground subsidence during the past several decades. In this paper, we investigate the time series InSAR technique for the generation of subsidence maps over Jiaxing region. 25 ENVISAT ASAR images acquired from Jan 2006 to Aug 2010 are used. The results show that serious subsidence has taken place in Xiuzhou district, Jiashan county, Pinghu county and Haiyan county. 4 subsidence centers, namely Huanggu town in Pinghu, Wangjiangting town in Xiuzhou, Tianning townin Jiashan, and Wuyuan town in Haiyan. 3 obvious subsidence belts are distributed in Jiaxing. Meanwhile in Tongxiang county, Haining county and Nanhu district, there is relatively seldom subsidence. The results are compared with 35 levelling measurements. The standard deviation of the error between the two data is 4.25 mm/year, which demonstrate that time series InSAR technique has good accuracy for subsidence monitoring in Zhejiang province, southeast of China, covered with lots of vegetation and waters.


Chen S.,Zhejiang Academy of Surveying and Mapping | Chen J.,Zhejiang Academy of Surveying and Mapping | Zuo Z.,Wuhan University | Sun M.,Wuhan University
Journal of Geomatics | Year: 2014

Brushed area of orthophoto is a common problem in the production of DOM (Digital Ortho Map). In this paper, we proposed an algorithm to detect and repair the brushed area automatically. It can greatly reduce the workload and improve the authenticity of mountain orthophoto production.


Sheng L.,Zhejiang University | Huang J.,Zhejiang University | Jin Y.,Zhejiang Academy of Surveying and Mapping | Tang X.,Nanjing University
2010 18th International Conference on Geoinformatics, Geoinformatics 2010 | Year: 2010

Gross primary productivity (GPP) and Net primary productivity (NPP) are key components of the terrestrial carbon cycle. In this paper, an improved light utilization efficiency model was used to estimate GPP and NPP in East China from 2001 to 2008. This model included two sub models: GPP model and respiration model. The data input into the model including remote sensing data: MODIS production such as MOD09A1 (reflectance), MOD15A2 (FPAR) and MOD12Q1 (land cover); Meteorologic data; DEM and Soil texture Map. In aid of IDL, we achieve quick and efficient evaluation of different spatial and temporal scale. The mean of NPP from 2001 to 2008 is 443.90 gc·m-2·a-1 and standard deviation is 16.51.


Li J.,Hohai University | Ji Y.,Zhejiang Academy of Surveying and Mapping | Yue J.,Hohai University | Peng G.,Hohai University | Song Y.,Hohai University
Journal of Hohai University | Year: 2015

Based on the Waveform data from Jason-2 and SARAL/AltiKa satellites, a new method of eliminating the gross error of altimetry data was developed. By eliminating the sea surface height that was not in the predetermined trajectory, the gross error in each segment of altimetry data was eliminated according to the sea surface height in each cycle of each Pass file, in order to improve the usability of satellite data in coastal areas. Through crossover adjustment, the time-varying signals for the radial orbit error and sea level were further weakened. The discrete sea surface height with high accuracy, which was obtained with the remove-restore technique, was gridded using the radial basis function method. A mean sea surface height model with grid resolutions of 2.5'×2.5' was established. The root mean square error between the sea surface height data from the established model and the data from tidal stations is ±0.017 m, and the standard deviation between the established model and MSS-CNES-CLS11 was ±0.070 m. The results show that the established mean sea surface height model for Zhejiang coastal areas is reliable. ©, 2015, Editorial Office of Journal of Hohai University (Nature Sciences). All right reserved.


Zhang G.,Wuhan University | Qiang Q.,Wuhan University | Luo Y.,Wuhan University | Zhu Y.,Zhejiang Academy of Surveying and Mapping | And 2 more authors.
Photogrammetric Record | Year: 2012

It has been widely accepted that the rational polynomial coefficient (RPC) model can be used as an alternative to rigorous sensor models of high resolution optical satellites for photogrammetric processing. In the application of the RPC model to synthetic aperture radar (SAR) image processing, it has been confirmed that the range-Doppler model can be replaced by the RPC model. Until now, however, orthorectification with the RPC model in SAR image processing has not been considered. This paper investigates how to perform orthorectification in SAR image processing with the RPC model. Following a brief introduction about the RPC model for spaceborne SAR imagery, an optimisation model is established and a method of conducting simulations with the RPC model is proposed. Finally, a series of experiments are performed in order to verify the correctness of the theory using TerraSAR-X, COSMO-SkyMed, ERS-2 and Envisat ASAR images as test data. By comparing the actual accuracy and the theoretical accuracy of the orthorectified imagery, the theory and methodology proposed in this paper are confirmed. © 2012 The Authors. The Photogrammetric Record © 2012 The Remote Sensing and Photogrammetry Society and Blackwell Publishing Ltd.


Wu H.A.,Chinese Academy of Surveying and Mapping | Zhang Y.H.,Chinese Academy of Surveying and Mapping | Luo G.F.,Zhejiang Academy of Surveying and Mapping | Kang Y.K.,Chinese Academy of Surveying and Mapping | Zhu Y.M.,Zhejiang Academy of Surveying and Mapping
International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences - ISPRS Archives | Year: 2016

Hangzhou, the capital of Zhejiang province has suffered serious ground subsidence during the past several decades, due to long term over-exploration of groundwater. In this paper, the time series InSAR technique using high resolution SAR images is investigated for the generation of subsidence maps over Hangzhou region. 29 TerraSAR-X images acquired from May 2012 to Sep 2015 are used. The results show that serious subsidence has mainly taken place in suburban area, including Yuhang district, Xiaoshan district and Binjiang district. 4 subsidence centers are discovered, namely Tangqi town in Yuhang with an average subsiding velocity of -29.6 mm/year, Xintang (-30.7 mm/year) in Xiaoshan, Zhujiaqiao town (-25.6mm/year) in Xiaoshan, and Miaohouwang town (-30.1mm/year) in Binjiang. The urban area is stable and ground rebound even take place in some places. The results are compared with 19 levelling measurements. The RMS error between them is 2.9 mm/year, which demonstrates that the high resolution TerraSAR-X images has good accuracy for subsidence monitoring in the southeast of China, covered by dense vegetation.

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