• 대한임베디드공학회논문지
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• 제3권4호
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• pp.244-250
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• 2008

This paper describes the design and implementation of an unmanned ground vehicle (UGV) and also estimates how well autonomous navigation and remote control of UGV can be performed through the optimized arbitration of several sensor data, which are acquired from vision, obstacle detection, positioning system, etc. For the autonomous navigation, lane detection and tracing, global positioning, and obstacle avoidance are necessarily required. In addition, for the remote control, two types of experimental environments are established. One is to use a commercial racing wheel module, and the other is to use a haptic device that is useful for a user application based on virtual reality. Experimental results show that autonomous navigation and remote control of the designed UGV can be achieved with more effectiveness and accuracy using the proper arbitration of sensor data and navigation plan.

• 대한원격탐사학회지
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• 제18권2호
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• pp.97-105
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• 2002

In this paper, we proposed a simplified strategy for the epipolarity of linear pushbroom imagery. The proposed strategy is verified on "Gupta and Hartly" sensor model and "Orun and Natarajan" sensor model. It is also compared with the precise epipolarity model of each sensor model on SPOT and KOMPSAT imagery. For the quantitative analysis, 20 ground control points are used as independent checking points. Based on the results, the accuracy of the proposed strategy is not different from that of the precise epipolarity model of each sensor model (below 0.1 pixels). Under the worst circumstance, the proposed strategy is robust. We can assure that the proposed strategy will show high accuracy on most of sensor models based on the co-linearity equations.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2006년도 Proceedings of ISRS 2006 PORSEC Volume II
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• pp.578-581
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• 2006

Usually to achieve precise geolocation of satellite images, we need to get GCPs (Ground control points) from individual scenes. This requirement greatly increases the cost and processing time for satellite mapping. In this article, we focus on finding appropriate sensor models for entire image strips composing of several adjacent scenes. We tested the feasibility of modelling whole satellite image strips by establishing sensor models of one scene with GCPs and by applying the models to neighboring scenes without GCPs. For this, we developed two types of sensor models: collinearity-based type and orbit-based type and tested them using different sets of unknowns. Results indicated that although the performance of two types was very similar, for modelling individual scenes, it was not for modelling the whole strips. Moreover, the performance of sensor models was remarkably sensitive to different sets of unknowns. It was found that the orbit-based model using attitude biases as unknowns can be used to model SPOT image strips of 420 Km in length.

• 한국토양비료학회지
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• 제42권2호
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• pp.70-78
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• 2009

질소 스트레스 조건에서 재배된 연초 (Nicotiana tabacum L.)의 생체량 및 질소영양 상태와 원격측정센서 반사율 지표의 상호관계로부터 센서의 반사율 지표를 활용한 연초의 질소 덧거름 시비량 결정 및 수량 예측을 위한 도구로서의 활용 가능성을 평가하였다. 이식 후 30일째의 rNDVI와 gNDVI, 그리고 40일째의 반사율 지표들은 건물중 및 질소흡수량과 밀접한 정의 상관(P<0.05)을 보였다. 40일째 분광방사계의 gNDVI와 Crop Circle passive 센서의 aNDVI는 각각 건물중을 85%와 84%, 질소흡수량을 85%와 92% 설명하였다. 수량 및 수확기 질소 흡수량은 정식 후 35일, 40일, 45일, 50일, 수확기에 측정된 엽록소 측정값 및 반사율 지표와 고도로 유의성 있는 정의 상관을 보였다. 정식 후 40일째 분광방사계에 의한 gNDVI 지표는 연초 수량변동의 72% 설명 가능한 관계를 나타냈다. 따라서 연초의 경우 이식 후 40일째에 측정한 gNDVI 반사율 지표는 실시간에 비파괴적으로 수량을 예측할 수 있음을 시사하였다. 그리고 40일째 gNDVI로 계산한 충족지수는 질소시비수준의 73%를 설명할 수 있었다. 따라서 반사율 지표를 이용한 충족지수는 연초의 질소영양상태를 추정하여 위치별 변량시비가 가능한 방법으로 활용 가능할 것으로 판단되었다.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2003년도 Proceedings of ACRS 2003 ISRS
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• pp.225-227
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• 2003

Traditional photogrammetry and satellite image rectification technique have been developed based on control-points for many decades. These techniques are driven from linked points in image space and the corresponding points in the object space in rigorous colinearity or coplanarity conditions. Recently, digital imagery facilitates the opportunity to use features as well as points for images rectification. These implementations were mainly based on rigorous models that incorporated geometric constraints into the bundle adjustment and could not be applied to the new high-resolution satellite imagery (HRSI) due to the absence of sensor calibration and satellite orbit information. This research is an attempt to establish a new Line Based Transformation Model (LBTM), which is based on linear features only or linear features with a number of ground control points instead of the traditional models that only use Ground Control Points (GCPs) for satellite imagery rectification. The new model does not require any further information about the sensor model or satellite ephemeris data. Synthetic as well as real data have been demonestrated to check the validity and fidelity of the new approach and the results showed that the LBTM can be used efficiently for rectifying HRSI.

• 대한원격탐사학회지
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• 제18권4호
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• pp.233-242
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• 2002

본 논문에서는 위성 궤도 정보를 사용하지 않는 새로운 에피폴라 기하모델을 제안하고, 선형 Pushbroom 영상의 에피폴라 기하모델을 위한 방법들과 정량적으로 비교 분석을 한다. 정량적 분석에 사용된 에피폴라 기하모델은 항공영상에 적용되는 중심투영(Perspective) 센서의 에피폴라 기하모델, Gupta와 Hartley의 에피폴라 기하모델, 궤도정보를 사용하는 Orun과 Natarajan 센서모델의 에피폴라 기하모델이다. 대전과 보령의 SPOT 영상과 대전과 논산의 KOMPSAT 영상에 대해 지상기준점, 지상기준점에서 생성한 모델링데이터, 위성 궤도정보 및 숙련된 운영자가 추출한 독립검사점을 사용하여 실험을 수행하였다. 실험 결과에 따르면 중심투영 센서의 에피폴라 기하모델과 Gupta와 Hartley의 에피폴라 기하모델은 평균적으로 1픽셀 이내의 정확도를 보였으나 일부 검사점에서 높은 오차를 보였다. 제안한 에피폴라 기하모델은 중심투영 센서나 Gupta와 Hartley의 에피폴라 기하모델보다 정확도가 높고, 궤도 정보를 사용하는 Orun과 Natarajan 센서 모델의 에피폴라 기하모델과 유사한 정확도를 보였다.

• 한국토양비료학회지
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• 제42권4호
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• pp.274-279
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• 2009

지상원격탐사 센서를 이용한 황색종의 적숙엽 판단기준을 평가하기 위하여 성숙기에 중엽과 상엽부위에 대하여 수확엽의 녹색도를 5개 수준으로 구분하여 여러 가지 센서지표들의 상호관계를 평가하였다. 건조엽의 색 특성은 색차계(Colorimeter, CR-300)를 이용하여 L, a, b값을 측정하였고 건조엽의 청색도는 육안관찰에 의한 분포정도를 수치화하여 비교 검토하였다. 수확엽의 녹색도에 따른 반사율은 550nm와 675nm에서 녹색도가 증가할수록 감소되는 특성을 보였다. 건조엽의 반사율은 미숙된 엽이 건조된 후 녹색이 잔류되었기 때문에 미숙엽의 675nm 반사율이 더 낮아졌다. 그 결과 동일한 엽위에서 생엽과 건조엽의 반사율지표는 직선적인 정의 상관을 보였다. 또한 건조엽의 청색도는 모든 센서지표들과 유의성 있는 정의 상관을 보였고 명도를 나타내는 색차계 L값은 센서지표들과 유의성 있는 부의 상관을 보였다. 따라서 건조엽의 청색도로 평가된 센서 종류별 적숙엽의 기준은 엽록소 측정치 SPAD 값은 22 이하, 엽록소 측정치 CM-1000 값은 135 이하, 그리고 원격탐사센서 Crop Circle의 gNDVI 값은 0.43 이하로 평가되었다.

• 대한원격탐사학회지
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• 제22권5호
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• pp.451-456
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• 2006

Epipolar images have to be generated to stereo display aerial images or satellite images. Pushbroom sensor is used to acquire high resolution satellite images. These satellite images have curvilinear epipolar lines unlike the epipolar lines of frame images, which are straight lines. The aforementioned fact makes it difficult to generate epipolar images for pushbroom satellite images. If we assume a linear transition of the sensor having constant speed and attitude during image acquisition, we can generate epipolar images based on parallel projection model (20 Affine model). Recent high resolution images are provided with RPC values so that we can exploit these values to generate epipolar images without using ground control points and tie point. This paper provides a procedure based on the parallel projection model for generating epipolar images directly from a stereo IKONOS images, and experimental results.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2005년도 Proceedings of ISRS 2005
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• pp.91-94
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• 2005

A numerical formula that presents relationship between a point of a satellite image and its ground position is called a sensor model. For precise geolocation of satellite images, we need an error-free sensor model. However, the sensor model based on GOES ephemeris data has some error, in particular after Image Motion Compensation (IMC) mechanism has been turned off. To solve this problem, we investigate three sensor models: Collinearity model, Direct Linear Transform (DLT) model and Orbit-based model. We apply matching between GOES images and global coastline database and use successful results as control points. With control points we improve the initial image geolocation accuracy using the three models. We compare results from three sensor models that are applied to GOES-9 images. As a result, a suitable sensor model for precise geolocation of GOES-9 images is proposed.

• 한국토양비료학회지
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• 제49권5호
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• pp.598-607
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• 2016

This study was conducted to evaluate the amount of nitrogen (N) top dressing based on the normalized difference vegetation indices (NDVI) by ground based sensors for leaf perilla under the polyethylene house. Experimental design was the randomized complete block design for five N fertilization levels and conventional fertilization with 3 and 4 replications in Gumsan-gun and Milyang-si field, respectively. Dry weight (DW), concentration of N, and amount of N uptake by leaf perilla as well as NDVIs from sensors were measured monthly. Difference of growth characteristics among treatments in Gumsan field was wider than Milyang. SPAD-502 chlorophyll meter reading explained 43.4% of the variability in N content of leaves in Gumsan field at $150^{th}$ day after seedling (DAS) and 45.9% in Milyang at $239^{th}$ DAS. Indexes of red sensor (RNDVI) and amber sensor (ANDVI) at $172^{th}$ day after seedling (DAS) in Gumsan explained 50% and 57% of the variability in N content of leaves. RNDVI and ANDVI at $31^{th}$ DAS in Milyang explained 60% and 65% of the variability in DW of leaves. Based on the relationship between ANDVI and N application rate, ANDVI at $172^{th}$ DAS in Gumsan explained 57% of the variability in N application rate but non significant relationship in Milyang field. Average sufficiency index (SI) calculated from ratio of each measurement index per maximum index of ANDVI at $172^{th}$ DAS in Gumsan explained 73% of the variability in N application rate. Although the relationship between NDVIs and growth characteristics was various upon growing season, SI by NDVIs of ground based remote sensors at top dressing season was thought to be useful index for recommendation of N top dressing rate of leaf perilla.