• Journal of the Korea Computer Graphics Society
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• v.13 no.3
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• pp.19-24
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• 2007

In this paper, we describe a method of defining an object's real length in order to compare objects' lengths precisely using all real length units in the real world. The browser in our study represents an object's length by referencing to the physical length property defined at modeling when it displays the object. Since objects' lengths are appropriately scaled according to these units, objects can be precisely and visually compared in sire using real world length units. The concept of defining the real length unit is extended to the X3D specification. The units are ranged from $10^{-24}(yotta)\;to\;10^{24}(yocto)$. In addition, we explain the method for processing LOD (Levels Of Detail) and for applying the property of LOLD (Levels of Length Detail) when objects with different LOLD are read into the browser.

• Journal of the Korea Computer Graphics Society
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• v.13 no.3
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• pp.25-31
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• 2007

Current computer graphics technology creates and displays virtual objects in a normalized environment. We cannot know or assume the real physical properties of objects related to appearance without textual information. It is also difficult to represent any two objects in relation to each other when the difference between the two objects' size is large because of the limited resolution of the computer display. In order to solve the problem, we define and implement the real length property among the physical properties in virtual environments. We define the concept of LOLD (Level of Length Detail) to represent real-world length for objects in metric units such as millimeter, meter, kilometer, etc.

• Journal of the Korea Computer Graphics Society
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• v.13 no.1
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• pp.25-32
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• 2007

Computer graphics technology has advanced such that all objects can be represented within a computer display. However, because computer displays have a finite resolution, the variety of objects that can be realistically represented together in the same view is restricted by the difference in their relative size. In addition, objects cannot be rendered according to their physical properties in terms of real length units in current computer graphics technology. To solve these problems, we have defined a method that allows objects to be described using real-world physical property units, such as metric units, in a computer graphics system, and developed a 3D browser based on X3D, which implements the concept of relative proportion properties.

• Journal of KIISE:Software and Applications
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• v.37 no.3
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• pp.194-204
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• 2010

A space, real or virtual, comprises regions as its parts and physical objects residing in them. A coherent and sophisticated representaion scheme for their spatial relations premises the precision and plausibility in its associated agents' inferencing on the spatial relations and the development of events occurring in such a space. The existing spatial models are not suitable for a comprehensive representation of the general spatial relations in that they have limited expressive powers based on the dichotomy between the large and small scales, or support only a small set of topological relations. The representaion model we propose has the following distinctive chracteristics: firstly, our model provides a comprehensive representation scheme to accommodate large and small scale spaces in an integrated fashion; secondly, our model greatly elaborated the spatial relations among the small-scale objects based on their contact relations and the compositional relations among their respective components objects beyond the basic topological relations like disjoint and touch; thirdly, our model further diversifies the types of supported relations by adding the container property besides the soildness together with considering the gravity direction. The resulting integrated spatial knowledge representation scheme considering the gravity allows the diverse spatial relations in the real world to be simulated in a precise manner in relation to the associated spatial events and provides an expression measure for the agents in such a cyber-world to capture the spatial knowledge to be used for recognizing the situations in the spatial aspects.

• Asia-pacific Journal of Multimedia Services Convergent with Art, Humanities, and Sociology
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• v.7 no.6
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• pp.897-906
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• 2017

Projection Mapping, also known as Spatial Augmented Reality(SAR) has attracted much attention recently and used for many division, which can augment physical objects with projected various virtual replications. However, conventional approaches towards projection mapping have faced some limitations. Target objects' geometric transformation property does not considered, and movements of flexible objects-like paper are hard to handle, such as folding and bending as natural interaction. Also, precise registration and tracking has been a cumbersome process in the past. While there have been many researches on Projection Mapping on static objects, dynamic projection mapping that can keep tracking of a moving flexible target and aligning the projection at interactive level is still a challenge. Therefore, this paper propose a new method using Unity3D and ARToolkit for high-speed robust tracking and dynamic projection mapping onto non-rigid deforming objects rapidly and interactively. The method consists of four stages, forming cubic bezier surface, process of rendering transformation values, multiple marker recognition and tracking, and webcam real time-lapse imaging. Users can fold, curve, bend and twist to make interaction. This method can achieve three high-quality results. First, the system can detect the strong deformation of objects. Second, it reduces the occlusion error which reduces the misalignment between the target object and the projected video. Lastly, the accuracy and the robustness of this method can make result values to be projected exactly onto the target object in real-time with high-speed and precise transformation tracking.