• 대한토목학회논문집
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• 제11권4호
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• pp.151-162
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• 1991

본 연구에서는 자료형태 및 전처리수준이 다른 위성영상자료를 이용하여 전처리수준에 따른 외부표정요소의 최적다항식형태와 위치결정정확도를 파악하고, 지상기준점의 획득방법 및 획득방법에 따른 3차원 위치결정정확도를 분석함으로서 SPOT 위성영상을 이용한 3차원 위치결정이론 및 프로그램을 개발하고 위치결정의 정확도를 향상시키는데 목적이 있다. 본 연구수행 결과 각 전처리수준에 대한 외부표정요소의 최적다항식형태(수준 1B; 15변수, 수준 1AP, 1A; 12변수)를 결정할 수 있었으며, 전처리수준에 따른 위치결정 정확도분석에서는 수준 1AP 위성사진의 정확도가 가장 좋았으나, 수치영상인 수준 1A도 유사한 정확도를 나타냄을 알 수 있었다. 또한, 지상기준점의 획득방법이 다른 수준 1A 수치영상의 3차원 위치결정 정확도를 분석한 결과, 지상기준점의 정확도가 양호한 경우 부가매개변수의 도입만으로 정확도 향상률이 큰 반면 지상기준점의 정확도가 저하되는 경우 부가매개변수의 도입만으로 정확도가 크게 향상되지 않아 조정체계에 과대오차소거이론이 포함된 동시조정이론을 적용함이 바람직함을 알 수 있었다.

• 천문학논총
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• 제8권1호
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• pp.67-82
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• 1993

We developed a real-time CCD photometric program for IBM PC compatibles. This program can perform several functions necessary for CCD photometry such as telescope control. filter rotation, CCD camera control and data acquisition, two-dimensional image processing, simple aperture photometry and automatic differential photometry. The image processing of a spiral galaxy M51 observed with the SNU 61cm reflector shows a well developed spiral structure. Simple aperture photometric results of 14 stars in open cluster NGC 6871 almost accorded with those from IRAF/APPHOT. And we could confirm the light variation of eclipsing binary EM Cep by simultaneous automatic differential photometry of 7stars in NGC 7160. Due to the excellence in the precision and efficiency of automatic differential photometry using CCD. this program is very useful for the study of small amplitude ${\delta}$ Sct type variables and of the photometric stability of B ${\sim}$ F type stars.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2006년도 Proceedings of ISRS 2006 PORSEC Volume II
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• pp.647-650
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• 2006

Compact Airborne Spectrographic Imager (CASI) hyperspectral imagery was acquired over the Little Miami River Watershed (1756 square miles) in Ohio, U.S.A., which is one of the largest hyperspectral image acquisition. For the development of a 4m-resolution land cover dataset, a hierarchical approach was employed using two different classification algorithms: 'Image Object Segmentation' for level-1 and 'Spectral Angle Mapper' for level-2. This classification scheme was developed to overcome the spectral inseparability of urban and rural features and to deal with radiometric distortions due to cross-track illumination. The land cover class members were lentic, lotic, forest, corn, soybean, wheat, dry herbaceous, grass, urban barren, rural barren, urban/built, and unclassified. The final phase of processing was completed after an extensive Quality Assurance and Quality Control (QA/QC) phase. With respect to the eleven land cover class members, the overall accuracy with a total of 902 reference points was 83.9% at 4m resolution. The dataset is available for public research, and applications of this product will represent an improvement over more commonly utilized data of coarser spatial resolution such as National Land Cover Data (NLCD).

• 대한원격탐사학회지
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• 제37권3호
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• pp.577-589
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• 2021

드론 매핑 시스템은 재난 피해 조사, 국토 환경 모니터링, 건설 공정 모니터링 등 여러 분야에 응용 가능하다. 드론에 장착된 다양한 개별 센서를 통합하여 활용하려면 시간동기화 등 여러가지 절차가 필요했다. 최근, 영상 센서와 GPS/INS가 함께 내장된 복합센서가 다수 출시되었다. 복합센서는 여러 가지 센서 데이터를 내부적으로 통합하여, 위치/자세를 영상 파일에 바로 태깅하여 제공한다. 이러한 복합센서를 드론 매핑 시스템에 활용하려면 매핑 정확도를 확인해 볼 필요가 있다. 이에 본 연구에서는 다양한 데이터 취득 환경과 사전 캘리브레이션 여부를 중심으로 복합센서의 매핑 정확도를 확인하였다. 첫째, 매핑 정확도가 지상기준점의 개수에 따라 어떻게 변하는지 살펴보았다. 지상기준점 개수가 2개일 때부터 총 RMSE가 1 m 이상에서 약 60 cm로 40 cm가량 줄어드는 것을 확인할 수 있었다. 둘째, 데이터 취득 상황과 사전 캘리브레이션 여부에 따른 매핑 정확도를 확인하였다. 지상기준점이 있는 경우에는 개수가 적을지라도 사전 캘리브레이션의 영향이 크지 않은 것을 확인할 수 있었다. 영상의 중복도가 충분하지 않을 때는 사전 캘리브레이션 하는 것이 정확도 개선에 영향을 주는 것을 확인할 수 있었다. 지상기준점이 없는 경우에는 카메라, 탑재체 모두 사전 캘리브레이션 하는 것이 정확도를 개선시키는데 영향이 있음을 확인하였다. 본 연구를 기반으로, 향후 복합센서를 이용한 드론 매핑 수행 시 데이터 취득 조건에 따라 지상기준점 측량과 캘리브레이션 과정을 효율화 하는데 기여할 것으로 기대한다.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2004년도 Proceedings of ISRS 2004
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• pp.656-660
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• 2004

The Mobile Mapping System is an effective method to acquire the position and image data using vehicle equipped with the GPS (Global Positioning System), IMU (Inertial Measurement Unit), and CCD camera. It is used in various fields of road facility management, map update, and etc. In the general photogrammetry such as aerial photogrammetry, GCP (Ground Control Point)s are needed to compute the image exterior orientation elements (the position and attitude of camera). These points are measured by field survey at the time of data acquisition. But it costs much time and money. Moreover, it is not possible to make sufficient GCP as much as we want. However Mobile Mapping System is more efficient both in time and money because it can obtain the position and attitude of camera at the time of photographing. That is, Indirect Georeferencing must use GCP to compute the image exterior orientation elements, but on the other hand Direct Georeferencing can directly compute the image exterior orientation elements by GPS/INS. In this paper, we analyze about the positional accuracy comparison of ground point using the Direct Georeferencing and Indirect Georeferencing.

• Journal of Biosystems Engineering
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• 제33권3호
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• pp.186-195
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• 2008

In this paper, a prototype tele-operative system with a mobile base was developed in order to automate cultivation of house melon. A man-machine interactive hybrid decision-making system via tele-operative task interface was proposed to overcome limitations of computer image recognition. Identifying house melon including position data from the field image was critical to automate cultivation. And it was not simple especially when melon is covered partly by leaves and stems. The developed system was composed of 5 major modules: (a) main remote monitoring and task control module, (b) wireless remote image acquisition and data transmission module, (c) three-wheel mobile base mounted with a 4 dof articulated type robot manipulator (d) exchangeable modular type end tools, and (e) melon storage module. The system was operated through the graphic user interface using touch screen monitor and wireless data communication among operator, computer, and machine. Once task was selected from the task control and monitoring module, the analog signal of the color image of the field was captured and transmitted to the host computer using R.F. module by wireless. A sequence of algorithms to identify location and size of a melon was performed based on the local image processing. Laboratory experiment showed the developed prototype system showed the practical feasibility of automating various cultivating tasks of house melon.

• 한국군사과학기술학회지
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• 제15권2호
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• pp.155-160
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• 2012

In this paper, a strip modeling method is developed for the acquisition of target positions in remote area and validated using the imagery of SPOT satellite. This method utilizes the parameters given in header files and constructs a camera model without ground control points. In most cases, the root mean squared error of check points is less than pixel size with one ground control point. The model error of reference image is evaluated using ground control points and used to remove the model error of target images acquired along the same satellite orbit, which enables one to calculate target positions in remote area where no ground control points are available.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2006년도 Proceedings of ISRS 2006 PORSEC Volume I
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• pp.204-207
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• 2006

COMS will receive two different meteorological signals in S-Band from IDACS (Image Data Acquisition and Control System) in ground station before transmitting them in L-Band to user station. MODCS (Meteorological Ocean Data Communication Subsystem) in satellite released the value of required PFD (Power Flux Density) to receive two signals. Thus, DATS (Data Acquisition and Transmission Subsystem) needs to send two signals to satellite with a satisfied EIRP. The value of minimum HPA (High Power Amplifier) output power was estimated by subtracting antenna directional gain and path loss between antenna and HPA from the needed EIRP in this paper. Besides the minimum output power of HPA, the maximum output power was also calculated with considering IMD (Inter-Modulation Distortion) characteristics. IMD is always occurred in the output of HPA when LRIT and HRIT are amplified by using single HPA as COMS application. In this paper, the setting of maximum output power was determined when the IMD of modelled HPA was corresponded to the requirement of MODCS.

• 한국정보통신학회논문지
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• 제20권6호
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• pp.1215-1220
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• 2016

사회가 고도의 디지털 정보화 시대로 급속히 발전함에 따라 영상 및 음성 데이터를 획득, 전송, 저장을 위한 멀티미디어 통신 서비스가 상용화 되어가고 있다. 그러나 여전히 데이터를 처리하는 과정에서 다양한 잡음에 의해 영상의 열화가 발생하고 있으며 이러한 잡음 제거에 관한 연구는 지금까지 계속되고 있다. 영상에 첨가되는 잡음에는 다양한 종류가 있으며, salt and pepper 잡음, AWGN, 복합잡음이 대표적이다. 따라서 본 논문에서는 영상에 첨가된 복합잡음의 영향을 완화하기 위하여 잡음 판단 후, salt and pepper 잡음은 국부 마스크 내의 잡음 밀도에 따라 선형 보간법, 히스토그램을 이용한 가중치 필터, 메디안 필터로 처리하고, AWGN은 국부 마스크의 화소 정보를 이용하여 가중치를 설정하고 처리하는 영상복원 필터 알고리즘을 제안하였다. 그리고 객관적 판단을 위해 기존의 방법들과 비교하였으며, 판단의 기준으로 PSNR(peak signal to noise ratio)을 사용하였다.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 1998년도 Proceedings of International Symposium on Remote Sensing
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• pp.252-256
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• 1998

Accurate mapping of satellite images is one of the most important Parts in many remote sensing applications. Since the position and the attitude of a satellite during image acquisition cannot be determined accurately enough, it is normal to have several hundred meters' ground-mapping errors in the systematically corrected images. The users which require a pixel-level or a sub-pixel level mapping accuracy for high-resolution satellite images must use a number of Ground Control Points (GCPs). In this paper, the performance of two geometric correction algorithms is tested and compared. One is the polynomial warping algorithm which is simple and popular enough to be implemented in most of the commercial satellite image processing software. The other is full camera modelling algorithm using Physical orbit-sensor-Earth geometry which is used in satellite image data receiving, pre-processing and distribution stations. Several criteria were considered for the performance analysis : ultimate correction accuracy, GCP representatibility, number of GCPs required, convergence speed, sensitiveness to inaccurate GCPs, usefulness of the correction results. This paper focuses on the usefulness of the precision correction algorithm for regular image pre-processing operations. This means that not only final correction accuracy but also the number of GCPs and their spatial distribution required for an image correction are important factors. Both correction algorithms were implemented and will be used for the precision correction of KITSAT-3 images.