• Title/Summary/Keyword: 왜곡 형상 기준

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Development of Coordinate Transformation Tool for Existing Digital Map (수치지도 좌표계 변환 도구 개발)

  • 윤홍식;조재명;송동섭;김명호;조흥묵
    • Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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    • v.22 no.1
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    • pp.29-36
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    • 2004
  • This study describes the development of coordinate transformation tool for transforming the digital map using newly derived transformation parameters which are determined from the data referred to the local geodetic datum and the geocentric datum (ITRF2000) and the distortion modelling derived from collocation method. We prepared 190 common points and used 107 points to calculate 7 transformation parameters. In order to evaluate an accuracy of coordinate transformation, 83 common points were tested. In this study, we used Molodensky-Badekas model to derive the 7 transformation Parameters. An accuracy of 0.22m was obtained applying 7 Parameters transformation and the distortion modelling together. It shows that the accuracy of coordinate transformation is improved 72% against the result of 7 parameters transformation only. We developed the transformation tool, GDKtrans, which can be transformed the digital map of scales 1/50,000, 1/25,000 and 1/5,000. We also analyzed the digital map of l/5,000 at six urban areas by GPS observations. The result shows less RMSE of about 1.9 m and large disagreement at position and features. Consequently, we suggests that l/5,000 digital map is necessary of whole revision.

Synthetic Aperture Sonar for Conformal Towed Array (왜곡된 형상을 갖는 어레이를 위한 합성 처리 기법)

  • 김준환;양인식;김기만;오원천;도경철
    • The Journal of the Acoustical Society of Korea
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    • v.19 no.4
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    • pp.77-83
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    • 2000
  • The previous synthetic aperture techniques have been investigated to increase signal gain, improve angular resolution and peak-to-sidelobe level ratios for towed line array sonar systems. The synthetic aperture method in this paper is performed for conformal array systems by mapping real elements on an axis to control like a linear array. The proposed method for the conformal array performs coherent processing of subaperture signals at successive time intervals in the beam domain via FFT transformations. This was confirmed by the simulation results and compared to the results from use of the synthetic aperture technique under the conformal array.

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Map registration of building construction plan drawing with shape matching of cadastral parcel polygon (필지 객체의 형상 정합을 이용한 건물 설계도면의 좌표 등록)

  • Huh, Yong;Yu, Kiyun;Yang, Sungchul
    • Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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    • v.31 no.3
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    • pp.193-198
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    • 2013
  • This study proposed a map registration method of a building construction plan drawing with shape matching of cadastral parcel polygon. In general, the drawing contains information about a building boundary and a cadastral parcel boundary. The shape of this cadastral parcel boundary should be same as that of the corresponding parcel polygon object in the KLIS continuous cadastral map. Thus, shape matching between two parcel boundary polygons from the drawing and cadastral map could present transformation parameters. Translation and scaling amounts could be obtained by difference of centroid coordinates and area ratio of the polygons, respectively. Rotation amount could be obtained by the rotation that presents the minimum Turning function dissimilarity of the polygons. The proposed method was applied for building construction plan drawings in eAIS for an urban area in Suwon. To assess positional accuracy of map registration, building polygons in registered drawings and aerial photos were compared. According to the accuracy of the cadastral map which is the reference dataset of the proposed method, the RMSE of corresponding buildings' corners was 0.95m and 2.37m in new and old urban areas, respectively.

Effects of Port Shape on Steady Flow Characteristics in an SI Engine with Semi-Wedge Combustion Chamber (1) - Velocity Distribution (1) (반 쐐기형 연소실을 채택한 SI 기관에서 포트형상이 정상유동 특성에 미치는 영향 (1) - 유속분포 (1))

  • Kim, Hyeongsig;Ohm, Inyong
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.40 no.7
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    • pp.417-427
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    • 2016
  • This paper is the first investigation of the steady flow characteristics of an SI engine with a semi-wedge combustion chamber as a function of the port shape. For this purpose, the planar velocity profiles were measured at the 1.75B position by particle image velocimetry. The flow patterns were examined with both a straight and a helical port. Two swirls were observed up to 4 mm valve lift with the straight port and up to 2 mm with the helical one; however, only one swirl was present after these lifts. The flow characteristics changed suddenly between 4 and 5 mm lift in the straight port; on the other hand, the change with lift was gradual with the helical port - the transition points between flow regimes were different with the port shapes. In addition, the centers of the swirls were relatively far from the cylinder center so that the effect of eccentricity may not be negligible at 1.75B, regardless the shape. The eccentricity values with the straight port were especially high - over 0.5 for all lifts. Finally, real velocities were found to be much lower than those predicted by the assumption of ISM evaluation, with the profiles differing qualitatively as well.

Scan Matching based De-skewing Algorithm for 2D Indoor PCD captured from Mobile Laser Scanning (스캔 매칭 기반 실내 2차원 PCD de-skewing 알고리즘)

  • Kang, Nam-woo;Sa, Se-Won;Ryu, Min Woo;Oh, Sangmin;Lee, Chanwoo;Cho, Hunhee;Park, Insung
    • Korean Journal of Construction Engineering and Management
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    • v.22 no.3
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    • pp.40-51
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    • 2021
  • MLS (Mobile Laser Scanning) which is a scanning method done by moving the LiDAR (Light Detection and Ranging) is widely employed to capture indoor PCD (Point Cloud Data) for floor plan generation in the AEC (Architecture, Engineering, and Construction) industry. The movement and rotation of LiDAR in the scanning phase cause deformation (i.e. skew) of PCD and impose a significant impact on quality of output. Thus, a de-skewing method is required to increase the accuracy of geometric representation. De-skewing methods which use position and pose information of LiDAR collected by IMU (Inertial Measurement Unit) have been mainly developed to refine the PCD. However, the existing methods have limitations on de-skewing PCD without IMU. In this study, a novel algorithm for de-skewing 2D PCD captured from MLS without IMU is presented. The algorithm de-skews PCD using scan matching between points captured from adjacent scan positions. Based on the comparison of the deskewed floor plan with the benchmark derived from TLS (Terrestrial Laser Scanning), the performance of proposed algorithm is verified by reducing the average mismatched area 49.82%. The result of this study shows that the accurate floor plan is generated by the de-skewing algorithm without IMU.

GIUH Variation by Estimating Locations (단위도 산정지점에 따른 GIUH 형상 변화에 관한 연구)

  • Joo, Jin-Gul;Yang, Jae-Mo;Kim, Joong-Hoon
    • Journal of the Korean Society of Hazard Mitigation
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    • v.11 no.1
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    • pp.85-91
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    • 2011
  • RV-GIUH must be applied at an outlet or a junction of highest order stream of a subbasin because the model was derived for basins following Horton's ordering system. However hydrograph is calculated at various locations which does not fit to the desirable points. Therefore, some guideline is required for RV-GIUH application in practice. This study would like to suggest the outlet location criteria for appling RV-GIUH at un-gauged basin. Locations were selected by moving to upstream from outlet of Sanganmi basin and unit hydrograph using derived and simple RV-GIUH were estimated at each location. As the results, the peaks of RV-GIUH in upstream were exaggerated because of distortion of length ratio and total stream length. To avoid this error, the location must be selected at 60% downstream of highest stream length. To apply RV-GIUH at various places, equations correcting distortion of total stream length were suggested. With the correcting equations, it can be possible that RV-GIUH is applied at 20% downstream of highest stream length. Application and precision of RV-GIUH will be improved through this research.