• Proceedings of the Korea Water Resources Association Conference
• /
• 2008.05a
• /
• pp.1799-1803
• /
• 2008

표면영상유속계는 하천 표면의 영상을 분석하여 유속을 산정하는 매우 실용적이며 간편한 장비이다. 그러나, 표면영상유속계를 이용하여 유량을 산정하고자 할 경우, 하천 표면의 평면 측량 자료와 하천의 단면 측량 자료가 반드시 필요하다. 이 때문에 표면영상유속계의 간편성과 유용성에도 불구하고, 이용자들이 쉽게 이용하기 어렵다는 그릇된 인식을 줄 수 있다. 만일 효율적이고 간편하게 하천의 단면을 추정할 수 있다면, 표면영상유속계를 마치 일반적인 프로펠러 유속계처럼 쉽게 이용할 수 있을 것이다. 이 연구는 일반적인 평면 측량없이, 두 대의 비디오 카메라로 이루어진 표면 영상 유속계를 이용하여 하천 평면을 계측하는 방법을 개발하는 것이다. 이를 통하여 표면 영상 분석 과정을 반자동화할 수 있게 된다. 두 대의 카메라를 이용한 평면 측량은 사진 측량 분야이나 컴퓨터 비전 분야에서 오랫 동안 연구되어 왔다. 이 기법을 표면영상유속계에 적용함으로써 간단하게 하천의 평면 좌표를 구할 수 있도록 하였다. 두 대의 카메라에 대해서는 직접 선형 변환법을 이용하여 내부 표정과 외부 표정을 수행하여 변환의 매개 변수들을 추정하였다. 추정된 변수들과 공간 전방 교회법을 이용하여 하천의 고정된 기준점들의 좌표를 측정한다. 측정된 좌표점들은 기울어진 영상을 연직으로 사영된 평면으로 변환하는 데 이용되며, 이 과정을 통하여 번거로운 하천의 평면 측량 과정을 생략할 수 있게 되었다. 온천천에 실제 적용하여 본 결과, 결과는 아직은 만족할 만한 정도는 아니나, 보다 정밀한 카메라의 보정 등을 통하여 보다 나은 결과를 도출할 수 있을 것으로 기대된다.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
• /
• v.26 no.4
• /
• pp.351-357
• /
• 2008

An aerial multi-looking camera system equips itself with five separate cameras which enables acquiring one vertical image and four oblique images at the same time. This provides diverse information about the site compared to aerial photographs vertically. The geometric relationship of oblique cameras and a vertical camera can be modelled by 6 exterior orientation parameters. Once the relationship between the vertical camera and each oblique camera is determined, the exterior orientation parameters of the oblique images can be calculated by the exterior orientation parameters of the vertical image. In order to examine the exterior orientation of both a vertical camera and each oblique cameras in the multi-looking camera relatively, calibration targets were installed in a lab and 14 images were taken from three image stations by tilting and rotating a non-metric digital camera. The interior orientation parameters of the camera and the exterior orientation parameters of the images were estimated. The exterior orientation parameters of the oblique image with respect to the vertical image were calculated relatively by the exterior orientation parameters of the images and error propagation of the orientation angles and the position of the projection center was examined.

• Korean Journal of Remote Sensing
• /
• v.19 no.6
• /
• pp.431-445
• /
• 2003

In this paper, we experimentally investigated the precision of 3D positioning using 4S-Van images in photograrmmetric perspective. The 3D calibration target was built over building facade outside and was captured separately by two CCD cameras installed in 4S-Van. After then, we determined the interior orientation parameter for each CCD camera through self-calibration technique. With the interior orientation parameter computed, the bundle adjustment was performed to obtain the exterior orientation parameters simultaneously for two CCD cameras using calibration target image and object coordinates. The reverse lens distortion coefficients were computed and acquired by least squares method so as to introduce lens distortion into epipolar line. It was shown that the reverse lens distortion coefficients could transform image coordinates into lens distorted image coordinates within about 0.5 pixel. The proposed semi-automatic matching scheme incorporated with lens distorted epipolar line was implemented with scene images captured by 4S-Van in moving. The experimental results showed that the precision of 3D positioning from 4S-Van images in photograrmmetric perspective is within 2cm in the range of 20m from the camera.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.7 no.4
• /
• pp.125-132
• /
• 1987

The bundle adjustment used in photogrammetric data reduction is based on the collinearity condition. Photogrammetry has been used in many non-topographic applications. Due to the necessities of having fiducial marks and knowing initial approximations for interior and exterior orientation elements in bundle adjustment, it cannot be applied when non-metric cameras are used. Marzan and Karara develop the DLT(Direct Linear Transformation) program which directly transforms comparator coordinates into object space coordinates without approximate values. In this paper, several modifications of original DLT program have been made for accuracy improvement in close-range photogrammetry using non-metric cameras. In modified program, gross error detection method and computation of exterior orientation elements are incorporated, and more iterations are introdued.

• Proceedings of the KIEE Conference
• /
• 2015.07a
• /
• pp.585-586
• /
• 2015

GIS(Gas Insulated Switchgear) 가스구획은 SF6 가스와 강화 에폭시로 만들어진 스페이서를 통해 절연 성능을 유지하고 있는데, 초기 설치 시 조립 오류로 인한 부유 물질이나 철 파편 등에 의한 절연 파괴 및 GIS의 장시간 운전에 따른 열화에 의한 절연 파괴로 아크 사고가 발생한다. 그러나 GIS는 가스로 밀폐된 타입이므로 열화 현상으로 생성되는 이물질 또는 균열에 의한 내부 절연 파괴 현상(내부 아크)을 정확히 알 수 없을 뿐 아니라 사고 위치를 확인하기 어렵다는 단점을 가지고 있다. 본 연구에서는 수동 광소자 방식을 이용하여 GIS 내부 아크발생 시 정확한 탐지 및 위치 표정이 가능하며, GIS 내부에서 발생되는 아크를 바로 제거하고 반복적인 아크가 발생되지 않도록 보호계전기에 의한 GIS의 재폐로 동작을 차단 할 수 있는 GIS 아크탐지 장치를 소개한다.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
• /
• v.5 no.2
• /
• pp.47-55
• /
• 1987

In this paper, the direct linear transformation is described in which a inner and exterior orientation parameters are treated as unknown for non-iterative direct space resection, and the computer program was developed to obtain object space coordinates. Image coordinates measurements are conducted with analogue stereo-plotter and digitizer. To prove the appropriateness of the two image coordinate measurement devices and the DLT method, the standard errors of object space coordinates are compared with semi-analytical method.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
• /
• v.37 no.3
• /
• pp.189-198
• /
• 2019

In photogrammetry, single photo resection is a method of determining exterior orientation parameters corresponding to a position and an attitude of a camera at the time of taking a photograph using known interior orientation parameters, ground coordinates, and image coordinates. In this study, we proposed a single photo resection algorithm that determines the exterior orientation parameters of the camera using cosine law and linear equation-based three-dimensional coordinate transformation. The proposed algorithm first calculated the scale between the ground coordinates and the corresponding normalized coordinates using the cosine law. Then, the exterior orientation parameters were determined by applying linear equation-based three-dimensional coordinate transformation using normalized coordinates and ground coordinates considering the calculated scale. The proposed algorithm was not sensitive to the initial values by using the method of dividing the longest distance among the combinations of the ground coordinates and dividing each ground coordinates, although the partial derivative was required for the nonlinear equation. In addition, since the exterior orientation parameters can be determined by using three points, there was a stable advantage in the geometrical arrangement of the control points.

• Journal of the Korean Society for Nondestructive Testing
• /
• v.35 no.5
• /
• pp.332-340
• /
• 2015

Acoustic emission (AE) is an effective nondestructive test that uses transient elastic wave generated by the rapid release of energy within a material to detect any further growth or expansion of existing defects. Over the past decades, because of environmental issues, the use of compressed natural gas (CNG) as an alternative fuel for vehicles is increasing because of environmental issues. For this reason, the importance and necessity of detecting defects on a CNG fuel tank has also come to the fore. The conventional AE method used for source location is highly affected by the wave speed on the structure, and this creates problems in inspecting a composite CNG fuel tank. Because the speed and dispersion characteristics of the wave are different according to direction of structure and laminated layers. In this study, both the conventional AE method and the energy based contour map method were used for source location. This new method based on pre-acquired D/B was used for overcoming the limitation of damage localization in a composite CNG fuel tank specimen which consists of a steel liner cylinder overwrapped by GFRP. From the experimental results, it is observed that the damage localization is determined with a small error at all tested points by using the energy based contour map method, while there were a number of mis-locations or large errors at many tested points by using the conventional AE method. Therefore, the energy based contour map method used in this work is more suitable technology for inspecting composite structures.

• Spatial Information Research
• /
• v.10 no.3
• /
• pp.407-419
• /
• 2002

In this study, the design of 4S-Van system is discussed fur the implementation of laser mapping system. Laser device is fast and accurate sensor that acquires 3D road and surface data. The orientation laser sensor is determined by loosely coupled (D)GPS/INS Integration. Considering current system architecture, (D)GPS/INS integration is performed far performance analysis of direct georeferencing and self-calibration is performed for interior and exterior orientation and displacement. We utilized 3 laser sensors for compensation and performance improvement. 3D surface data from laser scanner and texture image from CCD camera can be used to implement 3D visualization.

• Journal of Korean Society for Geospatial Information Science
• /
• v.8 no.2 s.16
• /
• pp.89-99
• /
• 2000

The Quality and Accuracy of digital image is important factor for decision of accuracy in digital photogrammetry because all the inside works in digital photogrammetry are based on digital image. But it is still difficult to ensure quality assurance and appication of data because there is no distinct criterion about quality and accuracy of digital image when the works in digital photogrammetry is accomplished. This study presents optimal resolution of aerial photo through error analysis of image coordinate using auto inner orientation in digital photograrnrnetry workstation. In second step, we are valified to optimum resolution of aerial photo image with orientation analysis. Finally, we are established to validity optimal resolution of aerial photo image with production of ortho image and mosaic image using optimal resolution aerial photo image.