• Proceedings of the KSRS Conference
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• 2003.11a
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• pp.753-756
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• 2003

The paper presents the results of the project GISMO, which aimed on generating and interactively visualising a 3D urban landscape model of the city of Stuttgart, Germany. With respect to the desired flexibility to support walkthrough and flyover applications, a combined approach using continuous level of detail, the impostor technique and a method for generalizing 3D building models was used to speed up the visualization. To reduce the costs of the project, the data collection tools and the visualization environment was built solely with open-source software.

• Journal of Korea Multimedia Society
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• v.7 no.12
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• pp.1729-1736
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• 2004

This paper proposes an efficient collision detection method in the dynamic spatial subdivisions for the MMORPG engine which requires realtime interactions. An octree is a suitable structure for static scenes or terrain processing. An octree spatial subdivision enhances rendering speed of scenes. Current spatial subdivisions tend to be highly optimized for efficient traversal, but are difficult to update quickly for a changing geometry. When an object moves to the outside extent for the spatial subdivisions, the acceleration structure would normally have to be rebuilt. The OSP based on a tree is used to divide dynamically wide outside which is the subject of 3D MMORPG. TBV does not reconstruct all tree nodes of OSP and has reduced rebuilding times by TBV information of a target node. A collision detection is restricted to those objects contained in the visibility range of sight by using the information established in TBV. We applied the HBV and ray tracing for an efficient collision detection.

• Journal of the Korean Institute of Landscape Architecture
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• v.24 no.3
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• pp.29-41
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• 1996

The purposes of this study were to develope some techniques which can be used in the landscape simulation process using PC based computer grahics. As a result, a couple of utilities were programmed in AutoLISP language. The one(DSLINE.LSP) is to digitize 2-dimensional structuer forms in the interactive mode considering error handling, and the other one (IMPOST.LSP) is for superimposing and visualizing the digitized plan data to 3-dimension solids & surfaces referring to topographic elevations of meshes in digital terrain model. By applying utilities to present site, the followings may be described. 1) The utility DSLINE.LSP for digitizing simplified building structure form were proved to be easy to input data of polygons including orthogonal edges by handling user coordinates system and checking invalid intersection and default colsing. 2) IMPOST.LSP utility for superimposing and visualizing tool were proved to be more complicated and speedy in calculating process compared with a practical application of modeling tool before rendering process in landscape simulation of built environment on topographic relief, on specially mesospace level of assessment.

• Journal of the Korea Society of Computer and Information
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• v.24 no.4
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• pp.51-56
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• 2019

In this paper, we propose an algorithm that can quickly generate and synthesize city maps in racing games. Racing games are characterized by moving a wide map rather than a fixed map, but designing and developing a wide map requires a lot of production time. This problem can be mitigated by creating a large map in the preprocessing step, but a fixed map makes the game tedious. It is also inefficient to process all the various maps in the preprocessing step. In order to solve this problem, we propose a technique to create a terrain pattern in the preprocessing process, to generate a map in real time, and to synthesize various maps randomly. In addition, we reduced unnecessary rendering computations by integrating view-dependent techniques into the proposed framework. This study was developed in Unity3D and can be used for various contents as well as racing game.

• Journal of the Korea Computer Graphics Society
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• v.24 no.2
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• pp.21-28
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• 2018

We present interactive methods for visualizing the cloud height data and the backscatter data collected from ceilometers in the three-dimensional virtual space. Because ceilometer data is high-dimensional, large-size data associated with both spatial and temporal information, it is highly improbable to exhibit the whole aspects of ceilometer data simply with static, two-dimensional images. Based on the three-dimensional rendering technology, our visualization methods allow the user to observe both the global variations and the local features of the three-dimensional representations of ceilometer data from various angles by interactively manipulating the timing and the view as desired. The cloud height data, coupled with the terrain data, is visualized as a realistic cloud animation in which many clouds are formed and dissipated over the terrain. The backscatter data is visualized as a three-dimensional terrain which effectively represents how the amount of backscatter changes according to the time and the altitude. Our system facilitates the multivariate analysis of ceilometer data by enabling the user to select the date to be examined, the level-of-detail of the terrain, and the additional data such as the planetary boundary layer height. We demonstrate the usefulness of our methods through various experiments with real ceilometer data collected from 93 sites scattered over the country.

• Journal of Mechanical Science and Technology
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• v.20 no.1
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• pp.29-41
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• 2006

Nowadays, with the advancement of computers, computer simulation linked with VR (Virtual Reality) technology has become a useful method for designing the automotive driving system. In this paper, the VR simulation system was developed to investigate the driving performances of the ASV (Advanced Safety Vehicle) equipped with an ACC (Adaptive Cruise Control) system. For this purpose, VR environment which generates visual and sound information of the vehicle, road, facilities, and terrain was organized for the realistic driving situation. Mathematical models of vehicle dynamic analysis, which includes the ACC algorithm, have been constructed for computer simulation. The ACC algorithm modulates the throttle and the brake functions of vehicles to regulate their speeds so that the vehicles can keep proper spacing. Also, the real-time simulation algorithm synchronizes vehicle dynamics simulation with VR rendering. With the developed VR simulation system, several scenarios are applied to evaluate the adaptive cruise controlled vehicle for various driving situations.

• Journal of Astronomy and Space Sciences
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• v.32 no.2
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• pp.113-120
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• 2015

When humans explore the Moon, lunar caves will be an ideal base to provide a shelter from the hazards of radiation, meteorite impact, and extreme diurnal temperature differences. In order to ascertain the existence of caves on the Moon, it is best to visit the Moon in person. The Google Lunar X Prize(GLXP) competition started recently to attempt lunar exploration missions. Ones of those groups competing, plan to land on a pit of Lacus Mortis and determine the existence of a cave inside this pit. In this pit, there is a ramp from the entrance down to the inside of the pit, which enables a rover to approach the inner region of the pit. In this study, under the assumption of the existence of a cave in this pit, a 3D model was developed based on the optical image data. Since this model simulates the actual terrain, the rendering of the model agrees well with the image data. Furthermore, the 3D printing of this model will enable more rigorous investigations and also could be used to publicize lunar exploration missions with ease.

• Journal of KIISE:Computer Systems and Theory
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• v.32 no.6
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• pp.314-323
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• 2005

This paper proposes a real-time 3D visualization system for situational awareness of Air force operations. This 3D system of situational awareness supports a high-level commander of Air force during the war game operations. These situation aware supporting data such as the aircraft track data of radar, aircraft schedule database, map and satellite image data are integrated into one structured data and those are visualized as 3D structure. By using an Out-of-Core method, we can visualize a 3D huge data in real-time in mobile notebook environment. The experiment shows several examples of 3D visualization supporting situation awareness for Air force operation.

• Transactions of the Korean Society of Automotive Engineers
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• v.12 no.4
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• pp.163-172
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• 2004

Nowadays, to analyze the dynamic characteristics of the automotive driving system, the computer simulation linked up with VR(Virtual Reality) technology is treated as the useful method with the improvement of computing ability. In this paper, the VR simulation system has been developed to investigate the driving characteristics of the ASV(Advanced Safety Vehicle) equipped with an ACC(Adaptive Cruise Control) system. For the purpose, VR environment which generates 3D graphic and sound information of the vehicle, the road, the facilities, and the terrain has been organized for the driving reality. Mathematical models of vehicle dynamic analysis including the ACC model have been constructed for computer simulation. The ACC modulates the throttle and brake functions to regulate the vehicle speed so that vehicles could keep proper spacing. Also, the real-time simulation algorithm synchronizes vehicle dynamic simulation with the graphic rendering. With the developed VR simulation system, simple scenarios are applied to analyze the dynamic characteristics. It is shown that the VR simulation system could be useful to evaluate the adaptive cruise controlled vehicle on various driving conditions.

• Proceedings of the Korean Information Science Society Conference
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• 2012.06c
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• pp.314-316
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• 2012

대용량 지형 데이터를 실시간에 렌더링 하기 위해 여러 가지 연속상세단계 기법들이 연구되었다. 하지만 이러한 방법을 적용해도 지형 데이터가 하드웨어에서 처리할 수 있는 크기보다 클 경우 과도한 간략화로 인한 기하오차가 발생하거나 프레임률이 저하된다. 또한 기존 연속상세단계 기법을 수행하기 위해 만들어진 자료구조들 또한 지형 데이터의 크기에 비례하여 커지므로 메모리와 전처리 시간이 많이 소요된다. 본 논문에서는 적은 개수의 정점으로 효과적인 지형 렌더링이 가능한 편향맵을 다해상도로 확장하여 별도의 자료구조가 따로 필요 없는 간단한 연속상세단계 기법을 제안한다. 이 방법은 적은 메모리 용량으로 높은 정확도의 지형을 실시간에 렌더링 할 수 있다. 연속상세단계 선택은 보다 빠른 처리를 위해 GPU에서 패치 단위의 테셀레이션을 통해서 단일 패스로 수행된다. 상세단계가 선택으로 세분화 된 지형의 각 정점들은 화면 공간상의 오차를 참조하여 각각의 상세단계를 선택한 후 해당되는 편향맵에 저장된 이동벡터만큼 이동하여 최종 지형 메쉬를 생성한다. 제안한 방법은 전처리 단계를 포함한 모든 처리가 GPU에서 수행되므로 속도가 빠르고 적은 정점으로 보다 정확한 지형을 렌더링 할 수 있다.