• 대한원격탐사학회지
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• 제16권4호
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• pp.367-373
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• 2000

Natural and artificial land features are very dynamic, changing somewhat repidly in our lifetime. It is important that such changes are inventoried accurately so that the physical and human processes at work can be more fully understood. Change detection is a technique used to determine the change between two or more time periods of a particular object of study. Change detection is an important process in monitoring and managing natural resources and urban development because it provides quantitative analysis of the spatial distribution in the population of interest. The purpose of this research is to detect environmental changes surrounding an area of Mountain Moscow, Idaho using Landsat Thematic Maper (TM) images of (July 8, 1990 and July 20, 1991). For accurate classification, the Image enhancement process was performed for improving the image quality of each image. A SPOT image (Aug. 14, 1992) was used for image merging in this research. Supervised classification was performed using the maximum likelihood method. Accuracy assessments were done for each classification. Two images were compared on a pixel-by-pixel basis using the post-classification comparison method that is used for detecting the changes of the study area in this research. The 'from-to' change class information can be detected by post classification comparison using this method and we could find which class change to another.

• 대한원격탐사학회지
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• 제24권5호
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• pp.445-452
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• 2008

Preliminary results are reported on ship detection using coherence images computed from cross-correlating images of multi-look-processed dual-polarization data (HH and HV) of ENVISAT ASAR. The traditional techniques of ship detection by radars such as CFAR (Constant False Alarm Rate) rely on the amplitude data, and therefore the detection tends to become difficult when the amplitudes of ships images are at similar level as the mean amplitude of surrounding sea clutter. The proposed method utilizes the property that the multi-look images of ships are correlated with each other. Because the inter-look images of sea surface are covered by uncorrelated speckle, cross-correlation of multi-look images yields the different degrees of coherence between the images and water. In this paper, the polarimetric information of ships, land and intertidal zone are first compared based on the cross-correlation between HH and HV images, In the next step, we examine the technique when the dual-polarization data are split into two multi-look images, It was shown that the inter-look cross-correlation method could be applicable in the performance improvement of small ship detection and the land masking, It was also found that a simple combination of coherence images from each co-polarised (HH) inter-look and cross-polarised (HV) inter-look data can provide much higher target-detection possibilities.

• 대한원격탐사학회지
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• 제20권6호
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• pp.409-418
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• 2004

LOD(Level of Detail)는 대용량의 데이터를 갖는 게임이나 애니메이션에서 실시간에 자연스러운 처리를 위해서는 사용되는 기법으로, i차원 게임이나 애니메이션에 자주 사용되고 있으며 3차원을 표현하기 위한 중요한 기술로 부각되고 있다. 본 논문에서는 기존의 2진 트리 방식에서 부모노드의 정보를 배제하여, 널리 사용되고 있는 2진 트리 방식인 ROAM(Realtime Optimally Adapting Meshes) 알고리즘 보다 메모리의 양을 적게 사용하며 성능은 오히려 향상된 새로운 LOD 알고리즘을 제시하고자 한다. 본 알고리즘의 성능을 검증하기 위하여 3차원 지형에서 실시간 네비게이션 시 기존의 ROAM알고리즘과 제안된 알고리즘을 비교하였으며 그 결과 메모리는 제안 알고리즘이 기존의 알고리즘에 약 1/4정도를 사용하고 수행 시간은 약 4배가량 빠른 것으로 조사되었다.

• 대한원격탐사학회지
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• 제22권3호
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• pp.199-209
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• 2006

The Global Land Cover 2000 (GLC 200) project, as a most recent issue, is to provide for the year 2000 a harmonized land cover database over the whole globe. The classifications were performed according to continental or regional scales by corresponding organization using the data of VEGETATION sensor onboard the SPOT4 Satellite. Even if the global land cover classification for Asia provided by Chiba University showed a good accuracy in whole Asian area, some problems were detected in Korean region. Therefore, the construction of new land cover database over Korea is strongly required using more recent data set. The present study focuses on the development of a new upgraded land cover map at 1 km resolution over Korea considering the widely used K-means clustering, which is one of unsupervised classification technique using distance function for land surface pattern classification, and the principal components transformation. It is based on data sets from the Earth observing system SPOT4/VEGETATION. Newly classified land cover was compared with GLC 2000 for Korean peninsula to access how well classification performed using confusion matrix.

• 대한원격탐사학회지
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• 제21권6호
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• pp.483-491
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• 2005

SAR 기술은 일반 레이더 분야와는 달리 영상을 제작해야 하므로 각종 신호처리 기술들이 필요하다. 이러한 기술들은 선진국에서 기술이전을 회피하는 분야로써 향후 항공기, 위성 및 무인기 SAR 체계를 국내 개발함에 있어 반드시 확보해야 할 분야이다. 본 연구에서는 SAR 영상 제작과 관련된 핵심기술들을 연구하고 실제로 활용도가 높은 상용 SAR 위성인 Radarsat을 대상으로 ASPR(ADD SAR Processor for Radarsat)을 자체 개발하고 성능을 검증해 봄으로써 향후 운용될 각종 SAR 체계에 필요한 영상제작 기술을 확보하고 국내개발 가능성을 검토해 본다. 개발된 ASPR의 성능비교를 위해 선진국 SAR 전문 업체인 MDA 및 Vexcel사에서 개발한 SAR Processor를 이용하여 비교 영상을 제작하였다.

• 대한원격탐사학회지
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• 제22권5호
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• pp.403-406
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• 2006

An algorithm for detection of yellow sand aerosols has been developed with infrared bands. This algorithm is a hybrid algorithm that has used two methods combined. The first method used the differential absorption in brightness temperature difference between $11{\mu}m\;and\;12{\mu}m\;(BTD1)$. The radiation at $11{\mu}m$ is absorbed more than at $12{\mu}m$ when yellow sand is loaded in the atmosphere, whereas it will be the other way around when cloud is present. The second method uses the brightness temperature difference between $3.7{\mu}m\;and\;11{\mu}m(BTD2)$. This technique is sensitive to dust loading, which the BTD2 is enhanced by reflection of $3.7{\mu}m$ solar radiation. First the Principle Component Analysis (PCA), a form of eigenvector statistical analysis from the two methods, is performed and the aerosol pixel with the lowest 10% of the eigenvalue is eliminated. Then the aerosol index (AI) from the combination of BTD 1 and 2 is derived. We applied this method to Multi-functional Transport Satellite-l Replacement (MTSAT-1R) data and obtained that the derived AI showed remarkably good agreements with Ozone Mapping Instrument (OMI) AI and Moderate Resolution Imaging Spectroradiometer (MODIS) aerosol optical depth.

• 대한원격탐사학회지
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• 제26권6호
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• pp.629-644
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• 2010

A real-time image georeferencing system requires all inputs to be determined in real-time. The intrinsic camera parameters can be identified in advance from a camera calibration process while other control information can be derived instantaneously from real-time GPS/INS data. The bottleneck process is tie point acquisition since manual operations will be definitely obstacles for real-time system while the existing extraction methods are not fast enough. In this paper, we present a fast-and-automated image matching technique based on the KLT tracker to obtain a set of tie-points in real-time. The proposed work accelerates the KLT tracker by supplying the initial guessed tie-points computed using the GPS/INS data. Originally, the KLT only works effectively when the displacement between tie-points is small. To drive an automated solution, this paper suggests an appropriate number of depth levels for multi-resolution tracking under large displacement using the knowledge of uncertainties the GPS/INS data measurements. The experimental results show that our suggested depth levels is promising and the proposed work can obtain tie-points faster than the ordinary KLT by 13% with no less accuracy. This promising result suggests that our proposed algorithm can be effectively integrated into the real-time image georeferencing for further developing a real-time surveillance application.

• 대한원격탐사학회지
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• 제9권2호
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• pp.7-19
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• 1993

In stereo vision, when we use two parallel axis images, small portion of object is contained and B/H(Base-line to Height) ratio is limited due to the size of object and depth information is inaccurate. To overcome these difficulities we take a non-parallel axis image which is rotated $\theta$ about y-axis and match other parallel-axis image. Epipolar lines of non-parallel axis image are not same as those of parallel-axis image and we can't match these two images directly. In this paper, we transform the non-parallel axis image geometrically with camera parameters, whose epipolar lines are alingned parallel. NCC(Normalized Cross Correlation) is used as match measure, area-based matching technique is used find correspondence and 9$\times$9 window size is used, which is chosen experimentally. Focal length which is necessary to get depth information of given object is calculated with least-squares method by CCD camera characteristics and lenz property. Finally, we select 30 test points from given object whose elevation is varied to 150 mm, calculate heights and know that height RMS error is 7.9 mm.

• 대한원격탐사학회지
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• 제12권1호
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• pp.26-42
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• 1996

CCD 지구 영상 실험 장치(CCD Earth Images Experiment, CEIE)는 우리별 1호의 탑재 체중의 하나이다. 우리별 1호가 발사된 후에 CEIE는 이제까지 약 500여장의 세계 곳곳의 지표면 영상을 촬영하였다. 내재한 방사학적(radiometric) 오차 및 기하학적(goemetric) 찌그러짐으로 인 해, 관측된 영상은 지표면의 모습과 아주 다르다. 관측된 영상을 다양한 목적의 응용을 위해 처리 하고 분석하기 전에 이러한 오차를 제거하기 위한 전처리 과정을 반드시 수행하여야 한다. 이 논 문은 우리별 1호가 관측한 영상에 방사학적 및 기하학적 보정을 수행하는 전처리 과정을 설명한 다.

• 대한원격탐사학회지
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• 제25권6호
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• pp.465-474
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• 2009

Convective/stratiform radar echo classification schemes by Steiner et al. (1995) and Biggerstaff and Listemaa (2000) are examined on a monsoonal front during the summer monsoon-Changma period, which is organized as a cloud cluster with mesoscale convective complex. Target radar is S-band with wavelength of 10cm, spatial resolution of 1km, elevation angle interval of 0.5-1.0 degree, and minimum elevation angle of 0.19 degree at Jindo over the Korean Peninsula. For verification of rainfall amount retrieved from the echo classification, ground-based rain gauge observations (Automatic Weather Stations) are examined, converting the radar echo grid data to the station values using the inverse distance weighted method. Improvement from the echo classification is evaluated based on the correlation coefficient and the scattered diagram. Additionally, an optimal use method was designed to produce combined rainfalls from the radar echo and Tropical Rainfall Measuring Mission Precipitation Radar (TRMM/PR) data. Optimal values for the radar rain and TRMM/PR rain are inversely weighted according to the error variance statistics for each single station. It is noted how the rainfall distribution during the summer monsoon frontal system is improved from the classification of convective/stratiform echo and the use of the optimal use technique.