• KSCE Journal of Civil and Environmental Engineering Research
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• v.12 no.1
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• pp.151-158
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• 1992

Topographic mapping from economic SPOT stereo imagery than aerial photographs has become possible. Many of authors have studied the possibility of base map revisions and the accuracy of results. They have concluded that the SPOT image is suitable for 1/50,000 to 1/100,000 topographic map. For topographic map, orthophoto and DTM generation from SPOT imagery, accurate exterior orientation parameters are needed. But since the geometric characteristic of SPOT image is dynamic linear array imagery, the conventional bundle adjustment for photogrammetry can not be directly applied. Reliability is the ability to detect gross error, which is called the internal reliability, and the effect of non-detectable gross error on the results of exterior orientation, which is called the external reliability. This paper shows how the reliability of SPOT imagery depends on the different coordinate systems, presentations of coordinate for flight direction, orders of exterior orientation parameters and distribution of control points, and thus analyses the theoretical reliability of the exterior orientation, which can provide a basis for the planning of SPOT projects.

• Journal of Korean Society for Geospatial Information Science
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• v.7 no.2 s.14
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• pp.143-153
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• 1999

GIS have become easier to use and very popular. In recent year digital photogrammetric systems ire becoming cost-effective tools to build and update GIS databases. In close-range photogrammetry for the acquisition of geospatial data, the bundle adjustment needs both initial approximate values and control points to solve the exterior orientation parameters. This paper gives a review of applied and potential algorithms for estimating Initial approximate values before the bundle adjustment, develope new algorithms for determine the exterior orientation parameters, and gives a cost-effective methods for close-range digital photogrammetric system Modifications of existing DLT algorithm were made in this study for providing an efficient, economic, and more accurate photogrammetric data reduction technique. These modifications include robust approaches for automatic detection and elimination of all lands of gross errors in the measurement data, and incorporation of GPS to reduce the number of control points necessary for a DLT solution. Also, this paper derives a new method for space resection from a monocular image. A major advantage of proposed method is that the solution can be uniquely and analytically determined without initial approximate values of exterior orientation parameters and without iterative computation.

• Ocean and Polar Research
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• v.39 no.2
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• pp.159-168
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• 2017

To evaluate the accuracy of UAV photogrammetry for Hyangho coast, eastern coast of Korea, we conducted a field experiment wherein UAV photogrammetry test was repeated three times. Since the Haygho coast is located within a military reservation zone, it was necessary to obtain permission to gain access to the beach and to have sensitive aerial photographs showing military facilities inspected and cropped. The standard deviation of the UAV shooting position between the three tests was less than 1 m, but repeatability of footprint on the ground was low due to wind-driven variability of the UAV pose. Self-calibrating bundle adjustment(SCBA) of implementing non-metric camera calibration was failed in one test. In two tests, the vertical error was twice as large as the pixel size except for those areas that were subject to security inspection and cropping. Given the problems that can arise with regard to the repeatability of the shooting area as well as the possibility of failure with regard to SCBA, we strongly recommend that UAV photogrammetry in coastal areas needs to be repeated at least twice.

• Korean Journal of Remote Sensing
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• v.35 no.5_1
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• pp.727-736
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• 2019

In this paper, we present how to create a point cloud for a target area using multiple unmanned aerial vehicle images and to remove the gaps and overlapping points between datasets. For this purpose, first, IBA (Incremental Bundle Adjustment) technique was applied to correct the position and attitude of UAV platform. We generate a point cloud by using MDR (Multi-Dimensional Relaxation) matching technique. Next, we register point clouds based on observation vectors between stereo images by doing this we remove gaps between point clouds which are generated from different stereo pairs. Finally, we applied an occupancy grids based integration algorithm to remove duplicated points to create an integrated point cloud. The experiments were performed using UAV images, and our experiments show that it is possible to remove gaps and duplicate points between point clouds generated from different stereo pairs.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.27 no.2
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• pp.177-186
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• 2009

Nowadays, as going to information society based knowledge, the informations are acquired, processed, serviced based digital environment. In surveying field, the trend have been changed from the analog foundation to the digital foundation. Also, aerial photogrammetry is being changed from analog aerial photogrammetry to digital aerial photogrammetry. In this paper, the analysis of accuracy is performed for the comparison of traditional aerial photogrammetry with digital aerial photogrammetry usign UltracamX in AT and Block Adjustment. As the results, Bundle adjustment in digital aerial photogrammetry with GPS/INS have more advantages than traditional independent adjustment in analog aerial photogrammetry. Digital aerial photogrammetry contributes the higher accuracy in AT and block adjustment more than analog aerial photogrammetry.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.10 no.4
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• pp.103-112
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• 1990

For this study, the full-scale model of Chumsungdae was selected as an object, and various photographs were obtained with metric camera for forming circular strips and blocks. The accuracies were analyzed according to the change of object distance and different configuration of control points by bundle adjustment, and the characteristics of results obtained through combined strips were drawn. This thesis suggests optimal analysis technique of cylindrical structures requiring all-side analysis such as cultural properties. As a result, it is possible to use control points positioned on only any one-side for all-side analysis, and control configuration is more important rather than the number of control points for increasing accuracy. In addition, it is desirable to locate control points in X, Y and Z plane uniformly, and it was shown as object distance was shorten and the number of combined strips increases, the accuracy of results was improved considerably.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.5 no.2
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• pp.109-120
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• 1985

This thesis is a study on multiple close range photogrammetry, and the purpose of this study is to develop the most accurate adjustment method of three dimensional object coordinates. This was achieved by comparing the standard errors of actual data to the computed values from 2 photos and multiple photos. The conventional methods for multiple photos have been analyzed by using geometric model formation. But in this study, the equation of collinearity condition which has been applied to aerial photogrammetry was derived to be a basic principle of close range photogrammetry, and the algorithm for analyzing multiple photos was developed using simultaneous bundle adjustment. The method used in this study, showed more homogeneous accuracy in coordinate and more consistent variance of error than those of conventional methods. It was found that the cases using 3, 4, and 5 photos were more accurate than using 2 photos; the accuracies were improved to 15%, 35%, and 50%, for each case. Thus this study is expected to be useful in measuring the geometry of historic monuments and other structures requiring high accuracy. Also the combined case of multiple photos is considered to be effective for the precise analysis of the objects which are difficult to measure for obstacles.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.17 no.3
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• pp.283-292
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• 1999

Aerotriangulation for the large scale mapping(photo-scale l/5,000) was studied with the projection center determined by kinematic DGPS positioning. For the feasibility study, the accuracy and error was analyzed with the comparison between a projection center from the conventional model adjustment and the projection center determined by the kinematic DGPS positioning. Kinematic DGPS-supported Bundle adjustment was also performed. The accuracy of projection center, determined by L1 phase data observed within 30 km from base station, was stable, and the planimetric accuracy(RMS) is 13 cm and the vertical accuracy(RMS) is 15 cm with 4 ground control points, which satisfies the national standard of digital mapping. Thus, this study shows that GPS-assisted aerotriangulation can be used for economic digital mapping.

• Proceedings of the Korean Society of Surveying, Geodesy, Photogrammetry, and Cartography Conference
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• 2003.10a
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• pp.199-204
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• 2003

Digital high resolution cameras are widely available, and are increasingly use in digital close-range photogrammetry. And photogrammetry instruments are developing rapidly and the precision is improving continuously, The building of 3D terrains of high precision are possible and the calculation of the areas or the earthwork volumes have high precision due to the development of the technique of the spatial information system using computer, In this study, using the digital camera which has capacity of keeping numerical value by itself and easy carrying, we analyze the positioning error according to various change of photographing condition. Also we t]v to find a effective method of acquiring basis data for 3D monitoring of high-accuracy in pixel degree through digital close-range photogrammetry with bundle adjustment for local terrain model generation and earthwork volume.

• Tuberculosis and Respiratory Diseases
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• v.72 no.2
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• pp.117-123
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• 2012

Optimal level of sedation and analgesia is important for the comfort and safety of critically ill patients. However, suboptimal sedation is relatively common in the intensive care unit (ICU) and it could cause prolonged mechanical ventilation and ICU stay, also increase delirium and ICU acquired weakness and resultant decreased survival. Therefore, accurate assessment of the level of sedation and analgesia, maintaining adequate level of sedation, and daily evaluation of each patient and following adjustment could be important treatment strategy in critically ill patients. Recently, the strategy for sedation in the ICU is changing toward the direction of lowering sedation level or even "no sedation" with concurrent use of analgesics and the use of ultra short acting analgesics could be helpful in some patients. Clinicians should be aware of the importance of algorithmic approach including daily interruption of sedative and assessment of sedation level and especially in the patients under mechanical ventilation, organizational approaches such as the 'ABCDE' bundle could improve the management of critically ill patients.