Showing papers by "State Bureau of Surveying and Mapping published in 2008"
TL;DR: In this paper, the authors developed the simplified equations that equivalently represent the single and double-differenced observation equations using corresponding pseudo-observations in single or multi-baseline solutions.
Abstract: The single and double-differencing operation of GPS observations is effectively used to eliminate nuisance parameters of receiver- and satellite-specific biases. According to the theorem of equivalent representation, we develop the simplified equations that equivalently represent the single and double-differenced observation equations using corresponding pseudo-observations in single or multi-baseline solutions. The transformation of the covariance matrix of original observables is no longer necessary. Therefore, the algorithms are very convenient for programming and efficient in computation. The unbiased estimate of the variance of unit weight is also derived from equivalent observation equations. The simplified equations are verified by numerical examples.
23 citations
01 Jan 2008
TL;DR: In this paper, the geodetic fundamental constants of Chinese geocentric 3D coordinate system (CGCS 2000) are defined and the corresponding coordinate frame with CGCS 2000 is reviewed.
Abstract: The definition and geodetic fundamental constants of Chinese geocentric 3D coordinate system(CGCS 2000)is concisely introduced,which will be employed since July 1,2008.The corresponding coordinate frame with CGCS 2000 is reviewed.The necessary conditions for the national frame to realize the CGCS 2000 include two parts.The first one consists of enough number,propriety density and high accuracy of national GNSS continuous operation stations,and second one is the national geodetic control network with high accuracy.For the time being the national frame only consisted of 2000 national GPS network and the national astro-geodetic network batch adjusted with the GPS network mentioned above.The customers may be satisfied with frame in recent years.The influences on the current existing Chinese maps caused by the change of the coordinate systems,such as the changes of latitude,longitude,Gauss plane coordinates of the surface points and their projection on the map,as well as the variation of the orientation and the length of the lines between the points on the map(including map outlines) are discussed,and the fundamental way to deal with it is introduced.
13 citations
Journal Article•
TL;DR: A new method based on genetic algorithms(GA) optimized back propagation neural network classification for remote sensing imagery is presented, which overcomes the defects that traditional approaches based on statistical principle have difficulties in distinguishing the objects with similar spectral characteristics.
Abstract: This paper presents a new method based on genetic algorithms(GA) optimized back propagation neural network classification for remote sensing imagery,which overcomes the defects that traditional approaches based on statistical principle have difficulties in distinguishing the objects with similar spectral characteristics,and the back propagation(BP) neural network method has difficulties in sufficiency and convergence.On the basis of the typical back propagation neural network classification,the optimization for the structure of neural network by genetic algorithms is presented,including the thresholds and connection weights of neural network and the number of neural nodes in the hidden layer of neural network.A coding method on float coding with variable length for genetic algorithms is then introduced,and the evolution method is improved to obtain an optimal back propagation neural network.In the end,an experimental test on remote sensing classification by using Landsat thematic mapper(TM) imagery in Dianshan Lake is conducted.The classification with the proposed approach is the most accurate,which proves its feasibility and validity.
5 citations
Journal Article•
TL;DR: The result of applying the improved network to deformation monitoring data processing indicates that the improved one is better than the traditional one in the aspect of precision.
Abstract: This paper presents some improvements on the convergent criterion and activation function of the traditional BP neural network algorithm,and also the measures to prevent vibration,accelerate convergence and avoid falling into local minimum.The result of applying the improved network to deformation monitoring data processing indicates that the improved one is better than the traditional one in the aspect of precision.
2 citations
01 Jan 2008
TL;DR: This paper studied the steps and technical problems of the construction of digital community, and analyzed the application objects, and summarized the 5 types of application objects in digital community.
Abstract: This paper studied the steps and technical problems of the construction of digital community.Firstly,it analyzed the application objects in the construction of digital community,and summarized the 5 types of application objects in digital community.Secondly,from the aspects of geographic information technology and the applied spatial location,it classified,investigated and managed the information resources of community,and put forward the technical requirement of the framework of digital community application system.Finally,it analyzed the services function of digital community.It provided the valuable reference and suggestion on the construction of digital community based on GIS.
1 citations
05 Sep 2008
TL;DR: Wang et al. as mentioned in this paper presented an approach for block-adjustment based on rational function model (RFM) with sparse GCPs by using SPOT-5 Images, which can achieve 5-9 m in planimetric and 2-3 m in height direction.
Abstract: High-resolution satellite images (HRSI) at sub-5m footprint such as IKONOS and SPOT-5 HRG/HRS images are becoming increasingly available to the earth observation community and their respective clients. SPOT-5 imagery is one of the main data sources for the project of West China topographic mapping (WChTM) which has been approved by the State Council of China in year 2006. In this paper, we present an approach for block-adjustment based on rational function model (RFM) with sparse GCPs by using SPOT-5 Images. To test the proposed approach, it has been applied to SPOT-5 images over 2 test-fields, one is in Baoji City, Chanxi, China, and another covers eastern part of Tibet Plateau, China. All test-fields are with variable terrain geomorphologic type and several tens of GCPs and check points measured by DGPS. The block-adjustment results show that with SPOT-5 HRS images and small number of GCPs we can achieve 5-9 m in planimetric and 2-3 m in height direction. From these experiments, itpsilas shown that with the proposed block-adjustment approach, by using SPOT-5 HRS imagery with small number of GCPs, satisfactory image orientation results can be achieved with a little bit better accuracy than those requirements from the Chinese surveying and mapping regulations for 1:50000 topographic maps.
1 citations
TL;DR: In order to satisfy the requirement for route location of a magnetic suspension project between Shanghai and Hangzhou, the authors proposed to adopt a new form of geodetic coordinate system, which is defined by meridians and parallel circles but with two coordinate parameters expressed by length.
Abstract: In order to satisfy the requirement for route location of a magnetic suspension project between Shanghai and Hangzhou, this paper proposes to adopt a new form of geodetic coordinate system, which is defined by meridians and parallel circles but with two coordinate parameters expressed by length. Not only the coordinate systems for route location along the whole line can be unified, but also the precision of lengths and angles obtained from simple formulas are very high and thereare not any map projection distortions. This has been proven by calculation.