• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.16 no.2
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• pp.203-211
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• 1998

A traditional method to produce three dimensional orthophoto map has been studied by digital photogrammetry which decides a height by digitally searching conjugate points on the stereo image. Many researches in digital photogrammetric field are still in progress to determine conjugate points automatically. In this study, we analyze the effect of accuracy of area-based image matching with changing eight types of target area size using four types of image pyramid. The result of image matching to each method compared with 1/5,000 digital mapping data. We decided a optimal size of target area on a percentage of image matching. Digital elevation model is generated by matching results and bundle method. As a result, three dimensional orthophoto map is made in terms of digital elevation model and orthophoto.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.27 no.6
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• pp.711-721
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• 2009

This study proposed digital close-range photogrammetric technique to measure deformation of I-plate-girder bridge. To compare deformation-measurement using the proposed method, a loading tester is used in the same time. As results, deviations of measuring values between the two methods range from 1mm to 2mm, and we could find-out simultaneously deflection and torsion of I-plate girder by repeated load of train. Then this study verified a measuring feasibility of I-plate-girder deformation by the proposed method. This may be alternative method of precise-stability inspection and manpower inspection.

• Korean Journal of Remote Sensing
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• v.21 no.3
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• pp.229-242
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• 2005

Photogrammetry is a current method of GIS data acquisition. However, as a matter of fact, a large manpower and expenditure for making detailed 3D spatial information is required especially in urban areas where various buildings exist. There are no photogrammetric systems which can automate a process of spatial information acquisition completely. On the other hand, LiDAR has high potential of automating 3D spatial data acquisition because it can directly measure 3D coordinates of objects, but it is rather difficult to recognize the object with only LiDAR data, for its low resolution at this moment. With this background, we believe that it is very advantageous to integrate LiDAR data and stereo CCD images for more efficient and automated acquisition of the 3D spatial data with higher resolution. In this research, the automatic urban object recognition methodology was proposed by integrating ultra highresolution stereo images and LiDAR data. Moreover, a method to enable more reliable and detailed stereo matching method for CCD images was examined by using LiDAR data as an initial 3D data to determine the search range and to detect possibility of occlusions. Finally, intellectual DSMs, which were identified urban features with high resolution, were generated with high speed processing.

• Journal of Korean Society for Geospatial Information Science
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• v.5 no.2 s.10
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• pp.99-110
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• 1997

Image matching to determine the conjugate points in stereo photos is the one of the most important subject in digital photogrammetry and many researches In digital photogrammetric field are on going to automate the image matching process. In this study, we analyzes the effect of allowable correlation coefficient, which controls the accuracy in areal based image matching, on the accuracy of digital photogrammetry. So, some areal based matching methods such as image correlation coefficient matching, image Pyramid matching and interest point matching, are implemented, and the effect of allowable correlation coefficient on accuracy of digital photogrammetry in each method is analyzed. As a result of this study, a method to determine the optimal correlation coefficient is presented.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.32 no.6
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• pp.563-570
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• 2014

This paper purposes on stimulating the dynamic behavior of a floating structure model with the image processing and the close-range photogrammetry, instead of the contact sensors. Previously, the movement of structures was presented by the exterior orientation estimation from a single camera following the space resection. The inverse resection yields to 6 orientation parameters of the floating structure, with respect to the camera coordinates system. The single camera solution of interest in applications is characterized by the restriction in terms of costs, unfavorable observation conditions, or synchronization demands when using multiple cameras. This paper discusses the theoretical determinations of camera exterior orientation by using the least squares adjustment, applied of the values from the DLT (Direct Linear Transformation) and the photogrammetric resection. This proposed method is applied to monitor motions of a floating model. The results of 6DOF (Six Degrees of Freedom) from the inverse resection were signified that applying appropriate initial values from DLT in the least square adjustment is effective in obtaining precise exterior orientation parameters. Therefore, the proposed method can be concluded as an efficient solution to simulate movements of the floating structure.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2014.10a
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• pp.219-221
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• 2014

The objective of this paper is to simulate the dynamic behavior of a floating structure model, using image processing and close-range photogrammetry, instead of the contact sensors. Previously, the movement of structure was presented through the exterior orientation estimation of a single camera by space resection. The inverse resection yields the 6 orientation parameters of the floating structure, with respect to the camera coordinate system. The single camera solution is of interest in applications characterized by restriction in term of costs, unfavorable observation conditions, or synchronization demands when using multiple cameras. This article discusses the theoretical determinations of camera exterior orientation based on Direct Linear Transformation and photogrammetric resection using least squares adjustment. The proposed method was used to monitor the motion of a floating model. The results of six degrees of freedom (6-DOF) by inverse resection show that the appropriate initial values by DLT can be effectually applied in least squares adjustment, to obtain the precision of exterior orientation parameters. Additionally, a comparison between the close-range photogrammetry and total station results was feasibly verified. Therefore, the proposed method can be considered as an efficient solution to simulating the movement of floating structure.

• Journal of the Architectural Institute of Korea Structure & Construction
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• v.35 no.1
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• pp.11-19
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• 2019

Recently, with the development of the fourth industrial revolution that has been achieved through the fusion of information and communication technology (ICT), the technologies of AI, IOT, BIG-DATA, it is increasing utilization rate by industry and research and development of application technologies are being actively carried out. Especially, in the case of unmanned aerial vehicles, the construction market is expected to be one of the most commercialized areas in the world for the next decade. However, research on utilization of unmanned aerial vehicles in the construction field in Korea is insufficient. In this study, We have developed a quantitative building inspection method using the unmanned aerial vehicle and presented the protocol for it. The proposed protocol was verified by applying it to existing old buildings, and defect information could be quantified by calculating length, width, and area for each defect. Through this technical research, the final goal is to contribute to the development of safety diagnosis technology using unmanned aerial vehicle and risk assessment technology of buildings in case of disaster such as earthquake.

• Asia-pacific Journal of Multimedia Services Convergent with Art, Humanities, and Sociology
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• v.5 no.4
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• pp.789-796
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• 2015

The first phase of architecture design is the field survey of the site and its surroundings. To gather the information there are two methods :the traditional method of an onsite survey, and recently using 3D geometry data and high quality image mapping from online services such as Google Earth. However, the urban condition is fast changing, and information from online services may lack sufficient information. This paper presents the to fast and effective site survey method for urban site using an affordable and fully automated UAV for the architectural design field.

• The Journal of the Korean dental association
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• v.56 no.9
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• pp.462-478
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• 2018

The presence of implant-prosthesis misfits can cause various complications. It is very important to detect misfits to prevent such complications. There are various evaluation methods for misfit assessment including clinical methods and laboratory in vitro methods. The clinical misfit evaluation includes radiographic analysis, visual observation, probing, Sheffield test, evaluation with disclosing materials, and screw resistance test. The laboratory in vitro evaluation method includes indirect modelling evaluation and direct metrological visualization. Of the indirect modelling methods, photoelastic stress analysis, finite element analysis, strain gauge analysis, and microbial colonization analysis were reviewed. Of the direct metrological visualization, microscopic analysis, 3-D photogrammetric analysis, coordinate measuring analysis, and radiographic analysis were reviewed. In this review, the characteristics, advantages and disadvantages of each method were evaluated.

• The Journal of Engineering Geology
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• v.15 no.2 s.42
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• pp.201-212
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• 2005

A photogrammetric camera system and a software have been built for capturing planned stereo images. To evaluate the system,25 planar data from a constructed rock slope were measured using both geological compass and photo system. Comparison of the data groups from both system showed matching relationship that falls within the error range of $5.25\pm4.53$ in strike and $3.18\pm3.17$ in dip angles, when the 2 standard deviation error distributions were considered. To evaluate the errors of the Photo matching and non planarity of the surface, orientations of the same plane were repeatedly measured 20times. These measurements showed error ranges of $8.2\pm3.4$in strike and $6.6\pm3.4$ in dip angle, considering the same error distributions. Measured strikes and dips were compared with the corresponding compass measurements in 5 constructed. slopes to test the system. Stereonet plots showed that the photo system measured data coincided well with the compass measurements. With these evaluations, the photo system can measure the planar structure in inaccessible locations with reliable accuracy at the same time reducing the data gathering period therefore resulting to an efficient geological survey.