Yeongdeungpo gu, South Korea
Yeongdeungpo gu, South Korea

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Lee I.S.,Korea Cadastral Survey Corporation | Lee J.O.,Dong - A University | Park H.J.,University of New South Wales | Bae K.H.,The Korean Association of Surveying and Mapping
KSCE Journal of Civil Engineering | Year: 2010

In contrast to other existing terrestrial surveying instruments, there are not many benchmark tests available for Terrestrial Laser Scanner (TLS) data quality specifications. This paper presents two possible approaches to the standardization of a TLS point data set. Firstly, the ranging accuracy from an instrument to the object is investigated by comparing measured distances by TLS with those of Total Station (TS). In this case, we use two different slope distances with one being about 25 m and the other, about 50 m in range. Secondly, the comparison of data intensity with six different materials, such as aluminum, a sheet of plywood, resin (black & white), steel (black), and laminate (yellow) is carried out. When comparing the distances measured by TS and those scanned by TLS, the standard deviations (Std.) of differences were found to be about 7 mm (50 m range) and 3 mm (25 m range). In the case of plane-fitting of point clouds, aluminum with white color gave better result than that of others, suggesting that the color of an object affects the intensity value of point clouds. It is expected that these results will contribute to the quality evaluation of TLS point clouds and the selection of standard targets. © 2010 Korean Society of Civil Engineers and Springer-Verlag Berlin Heidelberg.

Yun H.,Korea Aerospace University | Kim D.,Seoul National University | Song J.,Korea Aerospace University | Park B.,Korea Cadastral Survey Corporation | And 2 more authors.
Institute of Navigation - International Technical Meeting 2011, ITM 2011 | Year: 2011

This paper presents the master plans and preliminary test results of pseudolite-based Wide Area Differential GPS (WADGPS) demo system development project which is promoted by Korean government 2010 to 2014. Korean government developed the National GNSS Master Plan to support and coordinate the GNSS development in Korea. According to this plan, WADGPS research group in Seoul National University (SNU) GNSS Lab. has conducted a preliminary study for implementing WADGPS for 3 years (2002 to 2004), and has developed a Korean WADGPS test bed (KWTB) (Doyoon and Changdon 2003). In this research, we secured core technology of WADGPS, furthermore we verified the feasibility of Korean WADGPS implementation. Recently Korean government has resumed the project and planned to implement Pseudolite-based WADGPS for demonstrating the feasibility of Korean WADGPS. The main goal of this project is to show the capability of Korean WADGPS using the pseudolite and existing NDGPS infrastructures in real-time. This project is scheduled for 2010 to 2014 under the contract with the Ministry of Land, Transport and Maritime affairs (MLTM). After that, Korea will launch a geostationary multifunctional satellite with a navigation payload which will be broadcasting augmenting signals for GPS. In this paper, the research results about WADGPS algorithm which have been developed up to now and the project milestones will be described. And Korean pseudolite-based WADGPS architecture and deployed infrastructures will be introduced. To show the initial performance of the system, a simulation using NDGPS RINEX data has been conducted. In this paper, we presented current states of Korean WADGPS development project and also presented conceptual design and some considerations of the system. By simulating with real data, the system performance is expected to satisfy the Wide Area Augmentation System Initial Operation Capability (WAAS IOC) requirement. After this project, ground system will be secured so that it can be used for developing Korean satellite-based WADGPS. And pseudolite broadcasting system can be used for solving a GEO visibility problem like European Geostationary Navigation Overlay Service (EGNOS) pseudolite system (Ruizhi Chen 2007).

Park B.,Korea Cadastral Survey Corporation | Jeon S.,Seoul National University | Kee C.,Seoul National University
International Journal of Control, Automation and Systems | Year: 2011

The fixing process for cycle ambiguity is a major issue for attitude determination using multiple Global Navigation Satellite System (GNSS) antennas. Existing algorithms have used pseudorange with large noise and ambiguity-included carrier phase measurements so the volume of the ambiguity search space is inevitably large. We propose a new algorithm to determine the attitude of a rotating vehicle using Doppler measurement in a closed form. Using differential and angular velocity estimation, we can reduce the size of the search space and the number of ambiguity candidates. We present simulation results using one master and two slave GNSS antennas. For all the cases in our simulations, the probability of one epoch fix is over 97%. Moreover, we achieved resolution of the ambiguity in two consecutive epochs. In other words, the maximum time-to-first-fixed-attitude (TTFFA) of our algorithm is only two seconds. Our algorithm can reduce the computation load in the ambiguity resolution for rotational vehicle attitude; consequently, it will be helpful in rapid and accurate determination in a case of phase lock loss due to a complex maneuver such as a fast spin. © 2011 ICROS, KIEE and Springer.

Huh Y.,Korea Cadastral Survey Corporation | Kim J.,Seoul National University | Yu K.,Seoul National University | Cho S.,Korea Cadastral Survey Corporation
International Journal of Remote Sensing | Year: 2014

In this article, we propose a method to find corresponding object-set pairs between image and map polygon object data sets by means of latent semantic analysis. Latent semantic analysis assigns each polygon object of both data sets to feature vectors in a continuous geometric space in which the similarities between the vectors are proportional to the priorities to constitute a corresponding object-set pair. Thus, object clusters can be obtained by applying an agglomerative hierarchical clustering to the feature vectors. These object clusters are separated into object-set pairs according to the data sets to which the objects belong and are evaluated with a geometric matching criterion to find corresponding object-set pairs. We applied the proposed method to the segmentation result of a composite image with six normalized difference vegetation index (NDVI) images and a forest inventory map. The proposed method was compared to a graph-embedding-based method. The results showed that the proposed method found more corresponding object-set pairs with a similar accuracy in terms of shape similarities and shared information of found pairs. © 2014, © 2014 Taylor & Francis.

Lee I.S.,Korea Cadastral Survey Corporation | Park H.J.,University of New South Wales | Lee J.O.,Dong - A University | Kim Y.S.,Dong - A University
IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing | Year: 2011

This study presents the possible application of the airborne Light Detection And Ranging (LiDAR) survey technique to extract a cadastral shoreline in South Korea for the first time. This paper summarizes the results of two case studies to compare the airborne LiDAR-derived shoreline with other data sources, such as the digital topographic map, the seamless cadastral map, and the cadastral surveying. In this current study, the well-known contouring method is used to extract shorelines in combination with LiDAR-derived Digital Elevation Models (DEMs) and digital aerial images. Approximate Highest High Water Level (AHHWL) published by the Korea Hydrographic and Oceanographic Administration (KHOA) is introduced as the tidal reference elevation. This is close to a legally defined shoreline for the cadastral shoreline mapping in South Korea. The comparison results show that some discrepancies are found between the applied methods mentioned due to the inconsistent tidal data references and the heterogeneous data sources. However, it is verified that the airborne LiDAR surveying can lead to this method's increasing applications in the cadastral shoreline mapping. This is only possible under conditions of a new guideline for LiDAR surveying and re-establishment of the tidal reference. © 2008 IEEE.

Ogundipe O.,University of Nottingham | Lee J.K.,Korea Cadastral Survey Corporation | Roberts G.W.,The University of Nottingham Ningbo, China
Journal of Applied Geodesy | Year: 2014

GNSS signal multipath occurs when the GNSS signal reflects of objects in the antenna environment and arrives at the antenna via multiple paths. A bridge environment is one that is prone to multipath with the bridge structure, as well as passing vehicles providing static and dynamic sources of multipath. In this paper, the Wavelet Transform (WT) is applied to bridge data collected on the Machang cable stayed bridge in Korea. The WT algorithm was applied to the GNSS derived bridge defection data at the mid-span. Up to 41% improvement in RMS was observed afterwavelet shrinkage de-noisingwas applied.Application of this algorithm to the torsion data showed significant improvement with the residual average and RMS decreased by 40% and 45% respectively. This method enabled the generation of more accurate information for bridge health monitoring systems in terms of the analysis of frequency, mode shape and three dimensional defections. © Walter de Gruyter Berlin/Boston 2014.

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