• Journal of Advanced Navigation Technology
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• v.19 no.6
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• pp.507-514
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• 2015

The Spatial information research institute of the LX Korea land and geospatial informatix corporation manages infrastructure for the LX global navigation satellite system (GNSS), which comprises 30 monitoring stations nationwide. Since 2014, it has conducted network real-time kinematic (RTK) tests using the master-auxiliary concept (MAC). This study introduces the infrastructure of LX GNSS and presents the results of a performance analysis of the LX RTK service. The analysis was based on a total of 25 cadastral topographic control points in Jeonju, Seoul, and Incheon. For each point, performance was measured over one observation, two repeated observations, and five repeated observations. The measurements obtained from LX MAC and the VRS of the National Geographic Information Institute were compared with the announced coordinates derived from cadastral topographic control points. As a result, the two systems were found to have similar performance with average error and standard deviation differing only by 1 to 2 cm.

• Korean Journal of Geomatics
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• v.1 no.1
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• pp.1-5
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• 2001

This paper presents an investigation into the operational comparison of SPOT triangulation to build GCP library by analytical plotter and DPW (digital photogrammetric workstation). GCP database derived from current SPOT images can be used to other image sensors of satellite, if any reasons, such as lack of topographic maps or GCPs. But, general formulation of a photogrammetric process for GCP measurement has to take care of the scene interpretation problem. There are two classical methods depending on whether an analytical plotter or DPW is being used. Regardless of the method used, the measurement of GCPs is the weakest point in the automation of photogrammetric orientation procedures. To make an operational comparison, five models of SPOT panchromatic images (level 1A) and negative films (level 1AP) were used. Ten images and film products were used for the five GRS areas. Photogrammetric measurements were carried out in a manual mode on P2 analytical plotter and LH Systems DPW770. We presented an approach for exterior orientation of SPOT images, which was based on the use of approximately eighty national geodetic control points as GCPs which located on the summit of the mountain. Using sixteen well-spaced geodetic control points per model, all segments consistently showed RMS error just below the pixel at the check points in analytical instrument. In the case of DPW, half of the ground controls could not found or distinguished exactly when we displayed the image on the computer monitor. Experiment results showed that the RMS errors with DPW test was fluctuated case by case. And the magnitudes of the errors were reached more than three pixels due to the lack of image interpretation capability. It showed that the geodetic control points is not suitable as the ground control points in DPW for modeling the SPOT image.

• Spatial Information Research
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• v.16 no.3
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• pp.317-330
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• 2008

In this paper, the acquisition of digital imagery and the orthoimage generation were performed to set up working process. And another purpose of this thesis is to evaluate the accuracy of orthoimage by overlapping digital topographic map and digital cadastral map on it. The digital topographic map and digital cadastral map were superimposed on the orthoimage to check the accuracy as another approach of evaluation. The RMSE is ${\pm}0.364m$ in X direction and ${\pm}0.413m$ in Y direction with digital topographical maps(1/5,000). And the RMSE is ${\pm}1.283m$ in X direction and ${\pm}1.085m$ in Y direction with digital cadastral map. It is necessary for the application of a newly developed digital aerial camera to make an exact synchronization between GPS/IMU data and image data, use a technology for setting a standard image resolution and the number of ground control points.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.16 no.2
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• pp.149-158
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• 1998

The aim of this paper is to propose the technique of the two dimensional geodetic coordinates conversion between WGS84 and Bessel spheroids by the two-dimensional affine transformation modeling based on the UTM plane coordinates without the local geoid model which is essential to three dimensional coordinates conversion. Area of approximately $25\times{11}$ square km in the city of Inchon was selected as the test area. The transformation parameters were determined using the eleven triangulation control points in test area. And then, those paraneters were applied to the fifteen cadastral control points which selected as checking points for precision checking of transformation parameters. The average and standard deviations of the absolute values of the conversion residuals of checking points in latitude/longitude and N/E(UTM) and/or x/y(TM) are $\pm0.006"$$\pm0.013"$ and $\pm{17cm/}\pm{30cm}$ respectively. Also, coefficients for 7-parameters, 3-parameters and UTM model transformation computed according as sizes of transformed area, and then the transformed characteristics of checking points according to transformation methods analyzed synthetically.hetically.

• Journal of Korean Society for Geospatial Information Science
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• v.12 no.4 s.31
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• pp.45-51
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• 2004

Control stations managed by national and local governmes are associated with other survey work and constructing geography information and they are important assets in the national level as the positional standard of the country. Since these control points are managed as some type of register and the control points could not be easily updated due to the loss of control stations from construction work or urban development. Therefore, the users could not understand the present situation of the changed control stations. In this background, the aim of this study was to develop control station management system which the managers can use to efficiently maintain control points and to support the usage of the survey control points. For developing this system, we have designed input, update, network, analysis and statistic functions, and have constructed the system using Mapobject as main engine with other languages such as Visual C++ and Visual Basic. The graphic data used in this system are 1/5,000 digital map and digital cadastral map, and the attribute data of each control station are point name, map tile name, longitude and latitude coordinates, TM coordinates, surveying data with the format of year-month-day and control situation photos and so on. In the result of constructing this control station management system, we could achieve integrated management of graphic, attribute and positioning information of each control station.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.13 no.5
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• pp.201-208
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• 1993

The emergence of the Global Positioning System(GPS) with its benefits of speed and economy now offers an opportunity to analyse, strengthen, densify and constitute the control network, in addition to providing mapping, cadastral and engineering control under the unfavorable conditions. This research aims at the using of GPS compared to conventional geodetic positioning techniques in Korean primary control networks. A GPS test network of 10km baselines, which is measured and analysed by Wild GPS-System 200, are compared to the distances from EDM and official coordinates, and relative GPS heights are transformed to the height differences on the mean sea level. The results of this study confirms that using GPS merely as a new type of instrument is the most powerful method for the densification of the control points retaining existing networks and existing computational procedures.

• Proceedings of the Korean Association of Geographic Inforamtion Studies Conference
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• 2004.03a
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• pp.361-366
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• 2004

GPS 관측기법을 지적측량에 도입하기 위하여 GPS를 이용한 새로운 지적측량 모형(Model)을 정립하는 연구와 관련 기술들을 개발하는 연구가 활발히 진행되고 있다. 이와 같은 추세에 발맞추어 GPS 자료처리 및 기준점 성과산출과 관련하여 국내ㆍ외 측량 관련 상용 GPS 자료처리 소프트웨어의 현황 및 성능을 파악하고, 자료처리 알고리즘을 분석하여, 우리 실정에 적합한 GPS 자료처리 소프트웨어를 개발하는 것을 본 연구의 목적으로 한다. 본 연구에서는 국내ㆍ외의 전문 업체, 기관(대학)이 보유하고 있는 상용 소프트웨어 현황 분석 및 자료처리 방법에 따른 오차 발생을 연구하여 기선해석, 망 조정, 좌표변환 등 에 관련된 전문 소프트웨어 기능을 비교 분석하여 자료처리 산출성과의 정확도를 향상시키는 방향을 모색한다. 또한 기존 GPS 자료처리 소프트웨어에 적용된 알고리즘을 분석하고 지적측량성과 산출에 최적인 알고리즘을 연구하여 새로운 지적기준점 성과 산출을 위한 지적측량 성과계산 소프트웨어를 개발한다.

• Journal of the Korean Society for Railway
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• v.10 no.6
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• pp.685-691
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• 2007

In this paper through Honan high-speed railroad which is planned with the north and south axis, we will verify the feasibility of the coordinate conversion using railroad control points after regarding current planned-railroad as the linear central axises. From analysis, distortion of Y axis varies 21 cm to 40 cm diminishing to a gentle straight line, distortion of X axis varies 14 cm to 29 cm. Through a revision, the deviation value between the coordinates were 6 mm to 9 mm and it satisfied the allowable error of national geographic information institute which is following ITRF (International Terrestrial Reference Frame) and cadastral boundary survey (10 cm). consequently the coordinate conversion is possible using railroad control points as common control points.

• Journal of Korean Society for Geospatial Information Science
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• v.17 no.1
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• pp.97-104
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• 2009

Supplementary control point and urban control point have different purpose and characteristic in the view of installation but their measurement method and permanent marker position are very similar. Therefore if we could use them by connecting those two control point, we would improve the arrangement density as well as minimizing cost of restoration from the loss of control point. So we tried to suggest the possibility of connecting these two control point and usage by analysing positional accuracy of urban control point on the base of supplementary control point in this study. The result of this study is as following. When analysing the positional accuracy of 13 urban control points of the study areas, there were RMSE of connection errors between ${\pm}8cm$ and ${\pm}11cm$ for each measurement point. The result confirmed the possibility of connecting supplementary control point to urban control point and its usage within the allowable error tolerance that the present cadastral law permits.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.7 no.2
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• pp.35-43
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• 1989

The improvements of highly accurate and dense control networks are major requirements to carry out numerical surveying and a large scale mapping for cadastral renovation. In the most conventional photogrammetric solutions, adjusted control coordinates have been applied to block triangulations. However, this study, imploying real data and those of simulated as well, contributes to a simultaneously combined adjustment. It also contains such photogrammetric as photocoordinates and geodetic observations like distances, angles and hight differences. Its purpose is to introduce the improved results, despite it is not sufficient for the ground network. In addition, through the detection of gross error, more precise observational data can be selected for the better adjustment. All in all, the result of this study can be summarized as follows : First, even if the ground control points are not sufficient nor existed at all, the combination of pbotogrammetric and geodetic observations are improved its accuracy. Secondly, the case #2 is more accurate than that of #3, and the case #7 comes into close to that of #6.