• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.24 no.1
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• pp.9-18
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• 2006

This paper describes a new program called GPS_QC needed to check the quality of GPS observations before post-processing so that the surveyors can be improved the precision of GPS data analysis. The GPS_QC was designed to calculate the quality control (QC) parameters such as data gaps, cycle slips, low elevation angle, inonspheric delay, multi-path effects and DOP etc, within the period of GPS observation. It can be used to read and calculate the QC parameters from RINEX files. This program gives users brief statistics, time series plots and graphs of QC parameters. The GPS_QC can simply be performed the quality checking of GPS data that was difficult for surveyors in the field. It is expected that we can be improved the precision of positioning and solved the time consuming problem of GPS observation.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.37 no.6
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• pp.571-577
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• 2019

Since the introduction of digital cameras in an aerial-photogrammetry field on 2006, the technological paradigm related to the photogrammetry has been shifting from the analog types to digital types. However, current construction standard cost for the aerial-photogrammetry and the digital mapping are being mixed with analog-based concepts and digital-based methods. In the current standard cost, the monthly weather table is closely related to the calculation of the number of flying days in a taking of aerial photograph. The current monthly weather table uses the results calculated from the observation data of total cloud amount from 1999 to 2007. In this study, the monthly weather table was calculated using the total cloud data during ten years from 2009 to 2018. As a result, the newly calculated number of clear days for 29 stations was analyzed as 44 days decreased by 6 days. The maximum number of clear days decreased in Jinju as 23 days, and the highest decreased clearing days was February.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.26 no.2
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• pp.103-110
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• 2008

General lens, widely using in Photogrammetry, has narrow view, and have to adjust "Image-Registration Method" after obtain images and it need cost; economic, period of time. Recent days, there is various study that use wide-angle lens, usually for robotics field, put to practical use in photogrammetry instead of general lens. In this studies, distortion tendency of wide-angle lens and utilize the correction techniques suitable to wide-angle lens by the existing photographic survey methods. After carrying out the calibration of the wide-angle lens, we calculated the correction parameters, and then developed the method that convert the original image-point to new image-point correcting distortion. For authorization the developed algorithm, we had inspection about shape and position; there are approximately 2D RMSE of 3 pixel, cx = 2, and cy = 3 different.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.32 no.5
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• pp.515-525
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• 2014

Recently, because of increasing in downpour and typhoon, which are caused by climate changes, those sedimentation disasters, such as landslide and debris flow, have become frequent. Those sedimentation disasters take place in natural slope. In order to predict debris flow damage range within wide area, the response model is more appropriate than numerical analysis. However, to make a prediction using Random Walk Model, the regional parameters is needed to be decided, since the regional environments conditions are not always same. This random Walk Model is a probability model with easy calculation method, and simplified slope factor. The objective of this study is to calculate the optimal parameters of Random Walk Model for Umyeon mountain in Seoul, where the large debris flow has occurred in 2011. Debris flow initiation zones and sedimentation zones were extracted through field survey, aerial photograph and visual reading of debris flow before and after its occurrence via LiDAR DEM.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.27 no.1
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• pp.683-692
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• 2009

On-site remote sensing technique by using single lens reflex(SLR) digital camera will be expected as the useful tool for the vegetation measurement field such as a crop growth management, the monitoring of revegetation slope and the evaluation of environment. We reviewed the availability of the vegetation measurement using a digital camera which is sailed for general-purpose. As a result, we could analysis relationship with the illuminance of image plane and incidence energy of multitemporal observation images by doing gamma correction and exposure compensation. And also, we proposed the model formulas for the correction of influences of capturing angle and illuminance. In addition, we obtained high correlation of normalized difference vegetation index(NDVI) between digital camera and spectral photometer.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.35 no.6
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• pp.453-460
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• 2017

High voltage power transmission lines have been to keep the proper dip for maintenance. Powerline dips at a random point are conventionally measured by the direct or indirect observation but it is not only unsafe but labor-intensive. Therefore in this study we applied the photogrammetric technique to remotely measure the powerline dips. Since it is not easy to extract conjugate points from linear powerlines, we exploited the epipolar lines acrossing the powerlines for 3D mapping of the powerlines and dip measurements. The vertical mapping accuracy estimated at two field-surveyed power line points was 15~16cm that are within 5% of deflection at the points and less than 3% of the powerline dip.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.28 no.6
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• pp.627-636
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• 2010

Image segmentation technique is becoming increasingly important in the field of remote sensing image analysis in areas such as object oriented image classification to extract object regions of interest within images. This paper presents a new method for image segmentation to consider spectral and spatial information of high resolution satellite image. Firstly, the initial seeds were automatically selected using local variation of multi-spectral edge information. After automatic selection of significant seeds, a segmentation was achieved by applying MSRG which determines the priority of region growing using information drawn from similarity between the extracted each seed and its neighboring points. In order to evaluate the performance of the proposed method, the results obtained using the proposed method were compared with the results obtained using conventional region growing and watershed method. The quantitative comparison was done using the unsupervised objective evaluation method and the object-based classification result. Experimental results demonstrated that the proposed method has good potential for application in the object-based analysis of high resolution satellite images.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.11 no.1
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• pp.29-35
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• 1993

The vegetation such as grass, shrub, tree has been used to control the erosion and stabilize the slope for a long time. But the effects of vegetation on slope area is usually neglected in traditional stability analyses. There are many errors in slope analyses in thin soil mantles. Therefore the effects of vegetation is an important factor. But it is difficult and complex to represent the vegetation influence quantitatively in stability analysis. In this study, authors choose the landslide region at the Kum sung dong Kum-jung ku Pusan as a model area. Authors analyzed the degree of slope with the aerial photo interpretation and DTM data extracted from the topographic map, and the relationship of D.B.H. (diameter of breast height), height, and age of tree in field investigation data. Finally authors know the fact that landslide take place approximately 10 or 20 years later in arbitrary afforestable area where the degree of slope is 27. The prevention effect must be considered in the control of vegetation.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.23 no.3
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• pp.313-322
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• 2005

Rapid advances in technology and changes in human and cultural activities bring about changes to the earth surface in terms of spatial extension as well as time frame of the changes. Such advances introduce shorter updating frequency of maps and geospatial database. To satisfy these requirements, recent research efforts in the geoinformatics field have been focused on the automation and speeding up of the mapping processes which resulted in products such as the digital photogrammetric workstation, GPSIINS, applications of satellite imagery, automatic feature extraction and the LiDAR system. The possibility of automatically extracting buildings and generating contours from airborne LiDAR data has received much attention because LiDAR data produce promising results. However, compared with the manually derived building footprints using traditional photogrammetric process, more investigation and analysis need to be carried out in terms of accuracy and efficiency. On the other hand, generation of the contours with LiDAR data is more efficient and economical in terms of the quality and accuracy. In this study, the effects of various conditions of the pre-processing phase and the subsequent building extraction and contour generation phases for digital mapping have on the accuracy were investigated.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.14 no.1
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• pp.1-7
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• 1996

The idea of digital photogrammetry was first introduced into the photogrammetric community in early 1960s'. At that time, it was impossible to implement the idea due to inferior computer and digital image processing technology With the recent advancements in computer hardware/software and image processing techniques, digital photogrammetry has made its entry into the field of photogrammetry. The advent of digital photogrammetry also resulted from the increasing amount of digital data acquired through satellites, CCD cameras and digital scanning of photographs. Obviously, the major distinction between conventional photogrammetry and digital photogrammetry lies in the nature of primary input data (analogue versus digital), which could lead to a fully automated digital photogrammetric workstation. However, since digital photogrammetry is in its infant stage, virtually every task is an unsolved problem due to lack of understanding of theories and techniques. Upon considering the increasing demand of efficient digital mapping method and economical GIS database generation, the union of GIS and digital photogrammetry becomes ever clear. In this paper, the author addresses the current status of digital photogrammetry such as digital imagery and digital photogrammetric workstation as well as the role of digital photogrammetry in GIS.