Byounghyun Yoo, Korean Journal of Remote Sensing, 24(5), pp.497-506, 2008.

Abstract:

The needs for digital models of real environment such as 3D terrain or cyber city model are increasing. Most of applications related with modeling and simulation require virtual environment constructed from geospatial information of real world in order to guarantee reliability and accuracy of the simulation. The most fundamental data for building virtual environment, terrain elevation and orthogonal imagery is acquired from optical sensor of satellite or airplane. Providing interoperable and reusable digital model is important to promote practical application of high-resolution satellite imagery. This paper presents the new research regarding representation of geospatial information, especially for 3D shape and appearance of virtual terrain, and describe framework for constructing real-time 3D model of large terrain based on high-resolution satellite imagery. It provides infrastructure of 3D simulation with geographical context. Web architecture, XML language and open protocols to build a standard based 3D terrain are presented. Details of standard-based approach for providing infrastructure of real-time 3D simulation using high-resolution satellite imagery are also presented. This work would facilitate interchange and interoperability across diverse systems and be usable by governments, industry scientists and general public.

Keywords: interactive simulation, interoperability, X3D Earth, application infrastructure, standard

Byounghyun Yoo, Soonhung Han, Journal of Korea Information Science Society: Computer System and Theory, 33(10), pp.777-788, 2006.

Abstract:

This paper describes a displacement mapping technique which represents protruded shapes on the surface of an object. Previous approaches for image-based displacement mapping can represent only shapes depressed from the polygon surface. The proposed technique can represent shapes protruded from the underlying surface in real-time. Two auxiliary surfaces which are perpendicular to the underlying surface are added along the boundary of the polygon surface, in order to represent the pixels which overflow over the boundary of the polygon surface. The proposed approach can represent accurate silhouette of protruded shape. It can represent not only smooth displacement of protruded shape, but also abrupt displacement such as perpendicular protrusion by means of adding the supplementary texture information to the steep surface of protruded shape. By per-pixel instructions on the programmable GPU this approach can be executed in real-time. It provides an effective solution for the representation of protruded shape such as high-rise buildings on the ground.

Keywords: image-based rendering, motion parallax, protruded shape representation, real-time rendering, silhouette rendering, steep displacement mapping, surface details

Byounghyun Yoo, Soonhung Han, Journal of Korea Society for Simulation, 14(3), pp.55-66, 2005.

Abstract:

Virtual reality (VR) simulators have been extended to transfer knowledge and education, and demands for exhibition systems for science education and cultural experiences has also increased. Existing VR simulators, which are based on the dynamics equations of motion, cannot easily be adapted to changes in simulation contents. In order to effectively transfer knowledge and maintain interests through educational applications, an experiential system that has multi-sensory effects as well as motion effects is required. In this study, we designed and implemented a motion generation that is tailored to experiential exhibition systems and multi-sensory VR effects. Both the sense of motion which is generated from the movement of the viewpoint of the visual image, and motion effects which are constructed in advance, are applied to motion simulation. Motion effects which occur during interaction between the user and the exhibition system can be easily added. Various sensory cues that are appropriate to the exhibition system are also considered.

Keywords: motion generation, multi-sensory VR effect system, virtual reality simulator

Byounghyun Yoo, Soonhung Han, Journal of the Korean Association of Geographic Information Studies, 8(1), pp.49-62, 2005.

Abstract:

The VR (virtual reality) simulator such as helicopter simulation needs virtual environment of existing urban area. But the real urban environment keeps changing. We need a modeling method to make use of the GIS data that are updated periodically. The flight simulation needs to visualize not only buildings in near distance but also a large number of buildings in the far distance. We propose a method for modeling urban environment from aerial image and digital map with a comparatively small manual work. Image based modeling is applied to urban model which considers the characteristic of Korean cities. Buildings in the distance can be presented without creating a lot of polygons. Proposed method consists of the pre-processing stage which prepares the model from the GIS data and the modeling stage which makes the virtual urban environment. The virtual urban environment can be modeled with the simple process which utilizes the height map of buildings.

Keywords: aerial image, digital map, displacement map, flight simulation, image-based modeling, urban modeling, virtual environment

Byounghyun Yoo, Soonhung Han, Transactions of the Society of CAD/CAM Engineers, 9(2), pp.148-157, 2004.

Abstract:

Interactive simulators that simulate mechanical systems are being developed for the purpose of performance evaluation of product design, replacement of physical training, and entertainment game. Use of flight simulator is increasing to reduce risk and cost of physical training, and we need virtual environment which covers large area terrain. We need a method that can reduce development cost and construction time of virtual environment that simulate the real environment. There have been attempts to link GIS or remote sensing field with virtual reality. This paper examines a method that helps to construct virtual environment, and attempts to link geographic information with virtual reality. A construction method of virtual environment based on digital map and satellite image has been studied.

Keywords: flight simulation, GIS, level of detail, satellite image, virtual environment, virtual reality

Byounghyun Yoo, Soonhung Han, Transactions of the Society of CAD/CAM Engineers, 5(4), pp.293-300, 2000.

Abstract:

The non-manifold geometric modeling technique is to improve design process and to integrate design, analysis, and manufacturing by handling mixture of wireframe model, surface model, and solid model in a single data structure. For the non-manifold geometric modeling, Euler operators and other high level modeling methods are necessary. Boolean operation is one of the representative modeling method for the non-manifold geometric modeling. This thesis studies Boolean operations of non-manifold model with the data structure of selective storage. The data structure of selective storage is improved non-manifold data structure in that existing non-manifold data structures using ordered topological representation method always store non-manifold information even if edges and vertices are in the manifold situation. To implement Boolean operations for non-manifold model, intersection algorithm for topological cells of three different dimensions, merging and selection algorithm for three dimensional model, and Open Inventor™, a 3D toolkit of SGI, are used.

Keywords: non-manifold modeling, solid modeling, Euler operations, Boolean operations, intersection, boundary representation