• Journal of the Korean Association of Geographic Information Studies
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• v.12 no.1
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• pp.54-63
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• 2009

Various methods have been employed for acquiring beach surface data, which are used to monitor shoreline changes due to beach erosion. This study explores the possibility of constructing and implementing a surface model of beach using data acquired with a terrestrial laser scanner and RTK-GPS. Digital images and three-dimensional data of beach areas acquired at 20 cm intervals using a laser scanner were used to create a digital surface model covered with digital image. Seven months later, the beach area was surveyed using an RTK-GPS, and another beach model was constructed using the data collected with an accuracy of 1.9 cm. The use of a terrestrial laser scanner is expected to ensure acquisition of good quality results and help deal with seasonal changes in beach areas. Because readings obtained with the RTK-GPS are dependent on the number of sampling points in beach model, difficulties are encountered when fixing the survey points. However, RTK-GPS could be used to implement a three-dimensional model by correcting the hidden parts in images obtained using a terrestrial laser scanner. Therefore, an RTK-GPS and a terrestrial laser scanner can be used in combination to obtain more precise data for the construction of beach model data.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.20 no.4
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• pp.359-366
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• 2002

To survey satellites using only GPS can sometimes cause an impossible situation due to the many different geographical conditions as city cannon and obstacles. Although the GLONASS satellite system does not have the ability to survey itself accurately since it currently lacks of the number of usable satellites, it is able to bridge the gap when combined with GPS. This research used the GPS receiver to perform four analyzing methods to bring out the independent surveying method of GPS and combined surveying method of GPS and GLONASS(4 methods - number of satellites able to receive, precision of raw data, standard deviation from known point and RTK surveying). The result of test surveying satellites showed that 11 hours were possible to measure a minimum of 4 satellites when using an independent surveying method and 4 hours in unified surveying method in a month. Also, the precision of raw data using GPS and GLONASS surveying is 0.08~l.8m better than the GPS surveying in standard deviation. The deviation of known points by GPS and GLONASS also showed better accuracy by 3~l1mm. The RTK showed the range of differences in deviation of survey by leaning towards the GPS independent survey in Northing coordinate and leaned towards the Easting coordinate when GPS and GLONASS were combined. Nonetheless, it can't be said that the unified method is better, because it has limits to its capability.

• Proceedings of the Korean Society of Surveying, Geodesy, Photogrammetry, and Cartography Conference
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• 2006.04a
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• pp.513-519
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• 2006

South Korea is currently promoting cadastral computerization to modernize the field. Problems of cadastral mismatches are mostly resolved through cadastral mismatch organization projects. Three-dimensional cadastral drafting Is also on its way to wide adoption. In order to safeguard the property ownership rights of people and deliver accurate cadastral information quickly by constructing a three-dimensional cadastral information system, this study intends to provide solutions to survey real-time kinematic GPS (RTK-GPS) in mobile environments and to produce three-dimensional cadastral maps real-time using digital plane tables.

• Proceedings of the KAIS Fall Conference
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• 2011.12a
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• pp.105-108
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• 2011

본 연구에서는 기준국을 달리함으로써 관측 횟수를 달리하여 RTK-GPS 측량을 시행하여 보고 이에대한 정확도 분석을 토대로 지적측량에 효율적인 적용 방안을 제시하여 보고자 하였다. 실험지역을 선정하고 기준국을 달리하여 관측 후 기존 TS 성과와 비교한 결과, 제1기준국은 X좌표의 RMSE가 ${\pm}0.024m$, Y좌표의 RMSE가 ${\pm}0.016m$로 산출되었고, 제2기준국은 X좌표의 RMSE가 ${\pm}0.040m$, Y좌표의 RMSE가 ${\pm}0.029m$로 산출되었다. 이는 모두 현행 지적법령에서 규정하고 있는 성과인정 범위 이내의 오차이고, 더불어 두 성과의 차이는 크지 않았다. 따라서 GPS 위성자료 수신에 장애가 없다면 1회 관측으로도 충분히 안정적인 성과의 취득이 가능한 것으로 나타났다. 다만, 측량 환경에 따라 주변에 수신에 제약을 받는 요소가 있다면 이러한 지역에 대해서는 성과의 안정적인 취득을 위해 2회 이상의 관측이 필요할 것으로 판단된다.

• Journal of Korean Society for Geospatial Information Science
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• v.21 no.1
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• pp.65-75
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• 2013

In this study, one of the main aims is to build up a technical foundation for promoting the cadastral resurvey effectively and to improve the accuracy of cadastral surveying is to make use of precise surveying techniques in allowance of position errors as reference accuracy in cadastral resurvey, which is proper to obtain the sufficient accuracy of the cadastral control points, and parcel boundary points by introducing the GNSS-based surveying techniques on cadastral survey. In detail, the existing procedures and outcomes of cadastral survey were compared and analyzed for suggesting a better survey technique than that of the other techniques in a variety of aspects of capability of cadastral survey. The new skills and supports could be upmost importance when doing cadastral survey. What's more, essentially, 'The Measurement Department' makes all the efforts to establish 'The Surveying Regulations'. This could possibly apply GNSS-based surveying technique to the cadastral resurvey for the foreseeable future and this research paper suggested that how to improve absolute accuracy of cadastral reference points by means of putting to use the appropriate models of measurement further.

• Journal of Korean Society for Geospatial Information Science
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• v.22 no.4
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• pp.127-133
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• 2014

The purpose of this study is to evaluate the accuracy of Network-RTK(VRS) survey for applying to Ground Control Points(GCPs) survey required for mapping aerial photographs. Network-RTK has been serviced by National Geographic Information Institute since 2007. On the basis of the global coordinates system(ITRF2000), the coordinates of GCPs determined by Static GNSS survey with relative positioning techniques were regarded as accurate values. The coordinates of GCPs were also determined by Network-RTK survey using two kinds of receivers, and then they were converted into the global coordinates system(ITRF2000) by applying suitable geoid model and coordinate transformation. These coordinates of GCPs were compared with those from Static GNSS survey. The root mean squares error (RMSE) of coordinate differences between Network-RTK and Static GNSS was ${\pm}2.0cm$ in plane and ${\pm}7.0cm$ in height. Therefore, Network-RTK survey that enables single GNSS receiver to measure positions in short time is a practical alternative in positioning GCPs to either RTK survey that uses more than two sets of GNSS receivers or Static GNSS survey that requires longer observation time.

• Journal of Korean Society for Geospatial Information Science
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• v.10 no.3 s.21
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• pp.107-114
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• 2002

The cadastral surveying is essential for the effective management of a country, the D/B building of NGIS. Many of GPS applications require a positioning accuracy of several centimeters for rover in real-times. But, to achieve higher positioning accuracies in real-time, the double differencing technique should be implemented using carrier phase data. Corrected observations at the reference station can be transmitted and used to form double difference observations at the rover using a data link. In this study, the area accuracy of cadastral survey using the RTK GPS will be assessed, and will produce area of parcel of land. As the result of comparison among area by TS, planer surveying and RTK GPS. parcels-register for site is analyzed by this data. The results show that mean error of area calculated min. $2.42m^{2}{\sim}\;max.\;13.69m^{2}$ and RMSE calculated min. $0.00329\;{\sim}\;max.\;0.01846$.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.1
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• pp.59-65
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• 2012

The study conducted the measurement of RTK-GPS with changing the number of observation as the method to differ reference stations of RTK-GPS. Also it aimed to suggest an effective application plan for cadastral surveying based on the accuracy analysis accordingly. According to the result of selecting the study region, observing with different reference stations, and comparing with previous TS performance, the 1st reference station was calculated as ${\pm}0.024m$ for x-coordinate's RMSE and ${\pm}0.029m$ for y-coordinate's RMSE, and the 2nd reference station was calculated as ${\pm}0.040m$ for x-coordinate's RMSE and ${\pm}0.029m$ for y-coordinate's RMSE. All these results (the 1st and the 2nd reference stations) are allowed as acceptable performance within the margin of error according to the existing cadastral regulations, and there was no significant difference between two performances. Therefore, unless there was no problem in receiving GPS satellite data, it would be possible to secure stable performance enough with 1 observation. Depending on surveying environment that has possible problems in receiving data, however, 2 or more observations would be necessary to secure stable performance.

• Journal of the Korean Geophysical Society
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• v.9 no.2
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• pp.105-112
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• 2006

We intend to increase in eficiency of the topographic monitoring of seabed or riverbed by combinedwith DGPS, RTK GPS and echo sounder. For this study, we defined the error corection of the echo sounder with the experiment of water tank, which is considered the characteristic of estuary riverbedand then we developed the s/w for 3-dimensional monitoring of estuary riverbed and aplied the s/wto field test and improved the various problems. On analyzing topography of estuary riverbed by combinedby the movement of survey vessel to the end of the transducer was eliminated by geometrical rearangementand we defined the corection formula, . The sounding error about the echo sounder and characteristic of estuary riverbed was found by understanding the relation of average diameter and residual error and we defined corection formula, Y=-0.0474*ln(X) -0.045 by the regression analysis. and then we verified applicability of corection formula. This study that by Visual Basic must be useful applied in the topographic analysis of the estuary riverbed.

• Journal of Advanced Navigation Technology
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• v.15 no.5
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• pp.705-713
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• 2011

In this paper, we introduce two techniques for resolving integer ambiguities between reference stations, which is one of the most important processes in Network RTK correction generation process. Each techniques uses Hatch filter and combination of L1/L2 measurements and we used simulation data and real data to evaluate performance of the techniques. For evaluating performance of each technique, we compared corrections generated from user site and Network RTK. As a result, Network RTK with the technique which uses Hatch filter improves user performance much more than single baseline RTK does. Residual of user is smaller than a half size of wavelength so it does not affect user integer ambiguity resolution, however, it contains significant bias error. On the other hand, when we used the technique which uses combination of L1/L2 measurements, residual error of user is largely reduced compared to the technique using Hatch filter.