• 대한전기학회:학술대회논문집
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• 대한전기학회 2000년도 하계학술대회 논문집 D
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• pp.3047-3049
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• 2000

The ability to efficiently and robustly recover accurate 3D terrain models from sets of stereoscopic images is important to many civilian and military applications. To develop an effective and practical terrain modeling system. We propose the methods which detect unreliable elevations in digital elevation maps (DEMs). and fuse several DEMs from multiple sources into an accurate and reliable result. This paper focuses on two key factors for generating robust 3D terrain models. the ability to detect unreliable elevation estimates. and to fuse the reliable elevations into a single optimal terrain model. We apply the correlation score methodology to reconstruct accurate DEM for multi-image and show the method is more effective than the conventional averaging method. The photo-realistic simulator is used for generating four simulated images from ground truth DEM and orthoimage.

• 한국시뮬레이션학회:학술대회논문집
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• 한국시뮬레이션학회 2002년도 추계학술대회 논문집
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• pp.163-170
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• 2002

Terrain surfaces have to be modeled in very detail and wheel-surface contacting geometry must be well defined in order to obtain proper ground-reaction and friction forces for realistic simulation of off-road vehicles. Delaunay triangulation is one of the most widely used methods in modeling 3-dimensional terrain surfaces, and T-search is a relevant algorithm for searching resulting triangular polygons. The T-search method searches polygons in successive order and may not allow real-time computation of off-road vehicle dynamics if the terrain is modeled with many polygons, depending on the computer performance used in the simulation. In order to accelerate the searching speed of T-search, a terrain database of triangular polygons is modeled in multi-levels by adopting the LOD (Level of Detail) method used in realtime computer graphics. Simulation results show that the new LOD search is effective in shortening the required computing time. The LOD search can be even further accelerated by introducing an NN (Neural Network) algorithm, in the cases where a appropriate range of moving paths can be predicted by cultual information of the simulated terrain, such as lakes, houses, etc.. Numerical tests show that LOD-NN search almost double the speed of the original T-search.

• 한국대기환경학회지
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• 제14권6호
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• pp.643-650
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• 1998

Many atmospheric dispersion models have been based on the Gaussian distribution concept of plume spread. In application of Gaussian plume dispersion models, vertical dispersion coefficient 3 has been known as a sensitive variable. Vertical diffusivity K2 (=Oz2/2t) tends to increase with surface roughness, and the value of K3 in urban area is larger than that in rural area due to heat emission as well as increased roughness. Though Pasquill proposed a modification scheme for qz vs x system of Pasquill-Gifford under consideration of roughness effect in 1976, there appears not to be realistic reexamination on the modification scheme. In this study literature review on the effect of terrain or roughness on venical plume dispersion has been carried out in order to improve the prediction results of atmospheric pollution concentration. Again a few research objectives on vertical atmospheric dispersion in complex terrain were Proposed.

• 대한원격탐사학회지
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• 제22권5호
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• pp.351-356
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• 2006

Based on current practical needs for geo-spatial information on mobile platform, the main theme of this study is a design and implementation of dynamic 3D terrain rendering system using spaceborne imagery, as a kind of texture image for photo-realistic 3D scene generation on mobile environment. Image processing and 3D graphic techniques and algorithms, such as TIN-based vertex generation with regular spacing elevation data for generating 3D terrain surface, image tiling and image-vertex texturing in order to resolve limited resource of mobile devices, were applied and implemented by using graphic pipeline of OpenGL|ES (Embedded System) API. Through this implementation and its tested results with actual data sets of DEM and satellite imagery, we demonstrated the realizable possibility and adaptation of complex typed and large sized 3D geo-spatial information in mobile devices. This prototype system can be used to mobile 3D applications with DEM and satellite imagery in near future.

• 한국환경과학회지
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• 제14권3호
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• pp.297-309
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• 2005

Recently air quality modeling studies for industrial complex and large cities located in the coastal regions have been carried out Especially, the representation of atmospheric flow fields within a model domain is very important, because an adequate air quality simulation requires an accurate portrayal of the realistic three­dimensional wind fields. Therefore this study investigated effect of using high resolution terrain height data and FDDA with observational data to reflect local characteristics in numerical simulation. So the experiments were designed according to FDDA and the detail terrain height with 3sec resolution or not Case 30s was the experiment using the terrain height data of USGS without FDDA and Case 3s was the experiment using the detail terrain height data of Ministry of Environment without FDDA and Case 3sF was experiment using the detail terrain height data of Ministry of Environment with FDDA. The results of experiments were more remarkable, In Case 3s and Case 3sF, temperature indicated similar tendency comparing to observational data predicting maximum temperature during the daytime and wind speed made weakly for difference of terrain height Also Case 3sF had more adequate tendency than Case 3s at dawn.

• 대한공간정보학회지
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• 제5권2호
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• pp.77-85
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• 1997

컴퓨터 그래픽스 분야와 지리정보시스템 분야에서 사진과 같은 지형을 모델링하는 방법이 연구되고 있다. 이러한 지형 모델링은 비행 시뮬레이터, 임무 예행연습과 건설 계획과 같은 응용프로그램에 사용된다 지형을 표현하는 일반적인 접근방법은 수치고도모델을 사용하는 것이다. 수치고도모델이란 지형의 고도 값을 저장한 2차원 배열을 말하며 인공위성을 통해 얻어진다. 수치고도데이터를 가지고 3차원 지형을 표현하는 처리과정은 3단계로 구성되어진다. 첫 번째 단계는 수치고도 모델에서 정확도에 따라 의미점을 추출한다. 두 번째 단계는 추출된 의미점을 바탕으로 불규칙삼각망을 구성한다. 세번째 단계는 표현된 3차원 지형을 렌더링한다. 이 논문의 목적은 불규칙 삼각망을 가진 3차원 지형을 구성하는데 있다. 불규칙 삼각망의 구성을 위해 래디얼 스위프 알고리즘을 사용하였다. 래디얼 스위프 알고리즘은 불규칙 삼각망을 빠르고 효과적으로 만든다. 그러나, 불규칙 삼각망은 삼각형된 표면의 근사치에 의해 발생하는 문제를 가지고 있다. 이러한 문제를 해결하기 위해 최적화 삼각형에 의한 개선된 래디얼 스위프알고리즘을 제안한다.

• 대기
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• 제31권1호
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• pp.85-100
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• 2021

The necessity of accurate high-resolution meteorological forecasts becomes increasing in socio-economical applications and disaster risk management. The Korea Meteorological Administration Post-Processing (KMAPP) system has been operated to provide high-resolution meteorological forecasts of 100 m over the South Korea region. This study evaluates and improves the KMAPP performance in simulating wind speeds over complex terrain areas using the ICE-POP 2018 field campaign measurements. The mountainous measurements give a unique opportunity to evaluate the operational wind speed forecasts over the complex terrain area. The one-month wintertime forecasts revealed that the operational Local Data Assimilation and Prediction System (LDAPS) has systematic errors over the complex mountainous area, especially in deep valley areas, due to the orographic smoothing effect. The KMAPP reproduced the orographic height variation over the complex terrain area but failed to reduce the wind speed forecast errors of the LDAPS model. It even showed unreasonable values (~0.1 m s-1) for deep valley sites due to topographic overcorrection. The model's static parameters have been revised and applied to the KMAPP-Wind system, developed newly in this study, to represent the local topographic characteristics better over the region. Besides, sensitivity tests were conducted to investigate the effects of the model's physical correction methods. The KMAPP-Wind system showed better performance in predicting near-surface wind speed during the ICE-POP period than the original KMAPP version, reducing the forecast error by 21.2%. It suggests that a realistic representation of the topographic parameters is a prerequisite for the physical downscaling of near-ground wind speed over complex terrain areas.

• 한국콘텐츠학회논문지
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• 제12권2호
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• pp.78-85
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• 2012

본 논문은 3D 컴퓨터 게임 개발에 있어서 필수적인 3D 지형 툴 개발을 위한 효율적인 알고리즘을 제안한다. 특히 본 논문은 Picking 속도를 향상시키기 위한 교차검출 기법에 대하여 제안한다. 즉, 본 논문에서는 기존의 광선과 삼각형으로 구성된 교차검출 기법보다 광선과 평행사변형으로 구성된 효율적인 교차검출 기법을 제안함으로서 보다 빠른 Picking 속도를 확인할 수 있었다. 본 논문에서 제안하는 기법이 기존의 기법과 비교하여 더 빠른 Picking 속도를 내고 있다는 것을 확인하기 위해서는 DirectX SDK의 샘플들 중 Picking 예제를 실험에 사용하였다. 또한 기존의 기법과 본 논문에서 제안하는 기법으로 교차검출을 위한 함수 호출 횟수를 비교해본 결과 본 논문에서 제안하는 기법이 기존의 기법보다 약 50% 줄어든 것을 확인할 수 있었다. 그리고 이를 시간적으로 계산해 보았을 때에는 기존의 기법보다 1~2초 정도 단축되었음을 확인할 수 있었다. 추가적으로 본 논문에서는 3D 지형 툴로서 갖추어야할 기능들 중 텍스처 스플래팅, 지형의 높낮이 조절, 객체 배치 및 사실적인 물 효과 등의 기능들을 보다 개선된 알고리즘으로 제공함으로서 실제 3D 컴퓨터 게임 개발에 효율적으로 사용가능하도록 하였다.

• 대한기계학회논문집A
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• 제27권5호
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• pp.681-687
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• 2003

Terrain surfaces have to be modeled in very detail and wheel-surface contacting geometry must be well defined in order to obtain proper ground-reaction and friction forces fur realistic simulation of off-road vehicles. Delaunay triangulation is one of the most widely used methods in modeling 3-dimensional terrain surfaces, and the T-search is a relevant algorithm for searching resulting triangular polygons. The T-search method searches polygons in a successive order and may not allow real-time computation of off-road vehicle dynamics if the terrain is modeled with many polygons, depending on the computer performance used in the simulation. The dynamic T-search, which is proposed in this paper, combines conventional T-search and the concept of the dynmaic-window search which uses reduced searching windows or sets of triangular surface polygons at each frame by taking advantage of the information regarding dynamic charactereistics of a simulated vehicle. Numerical tests show improvement of searching speeds by about 5% for randomly distributed triangles. For continuous search following a vehicle path, which occurs in actual vehicle simulation, the searching speed becomes 4 times faster.

• 한국콘텐츠학회논문지
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• 제6권5호
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• pp.42-55
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• 2006

대부분의 멀티미디어 시스템들의 환경은 수동적인 배경으로 이루어진다. 그러나 가상환경에서 실세계 시뮬레이션에 있어서 지형은 바람이나 비, 구름과 같은 많은 이벤트에 영향을 미친다. 그러므로 지형과 기상 현상 모델링은 현실적인 가상환경을 시뮬레이션 하기 위하여 필요하다. 이러한 모델링에서는 높이와 지역정보 뿐만 아니라 온도와 습도와 같은 환경적 요소도 중요하다. 하나의 이벤트는 전제조건, 절차, 결과로 이루어지며, 이벤트의 결과가 다른 이벤트의 전제조건을 만족하는 형식의 인과관계를 통하여 여러 가지 이벤트들이 발생하게 된다. 본 논문에서는 등고선을 이용하여 자연현상 시뮬레이션에서 환경이 되는 개체들의 범위와 속성들을 표현하고 이를 통해 자연현상 이벤트를 표현하는 방법을 제시한다.