• Journal of KIISE:Computer Systems and Theory
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• v.31 no.12
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• pp.682-691
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• 2004

We present a novel haptic sculpting system where the user intuitively adds to and carves out material from a volumetric model using new sculpting tools in the similar way to handling real clay Haptic rendering and model deformation are implemented based on volumetric implicit surface. We enhance previous volume-based haptic sculpting systems by presenting fast and stable force computation on 3D models to be deformed. In order to bridge the gap between fast haptic process (1 KHz) and much slower visual update frequency(~30Hz), the system generates intermediate implicit surfaces between two consecutive physical models being deformed. It performs collision detection and force computation on the intermediate surface in haptic process. The volumetric model being sculpted is visualized as a geometric model which is adaptively polygonized according to the surface complexity. We also introduce various visual effects for the real-time sculpting system including mesh-based solid texturing, painting, and embossing/engraving techniques.

• Journal of the Korean Society of Radiology
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• v.1 no.2
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• pp.23-30
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• 2007

This paper presents a method of generating 3-dimensional images by preprocessing 2-dimensional abdominal images obtained using CT (computed tomography) and MRI (magnetic resonance imaging) through segmentation, threshold technique, etc. and apply the method to virtual endoscopy. Three-dimensional images were visualized using indirect volume rendering, which can render at high speed using a general-purpose graphic accelerator used in personal computers. The algorithm used in the rendering is Marching Cubes, which has only a small volume of calculation. In addition, we suggested a method of producing 3-dimensional images in VRML (virtual reality modeling language) running on the Web browser without a workstation or an exclusive program. The number of nodes, the number of triangles and the size of a 3-dimensional image file from CT were 85,367, 174,150 and 10,124, respectively, and those from MRI were 34,029, 67,824 and 3,804, respectively.

• Journal of the Korea Computer Graphics Society
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• v.10 no.1
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• pp.7-13
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• 2004

본 논문에서는 cavity 변형 물체의 전역적 변형 형태는 유지하면서 계산 복잡도를 줄이기 위하여 모델의 다중해상도적 표현 기법 및 서로 다른 상세 레벨간 물리적 특성변수에 대한 적응기법을 제안한다. 또한, 객체의 안정적 변형을 지원하기 위한 형태유지 스프링을 제안한다. 일반적으로 위나 풍선과 같은 cavity 변형객체는 전체 구성노드의 수를 줄이기 위하여 표면 메쉬 구조로 모델링 된다. 이 경우, 표면의 인접 노드만이 감쇠(damping) 스프링으로 연결되고, 모델의 체적정보의 부재로 인하여 외부 힘이 일정시간 동안 지속적으로 주어지는 경우, 객체의 형태변형이 왜곡되고, 초기형태로의 복원이 불가능해진다. 본 논문에서 제안하는 형태유지 스프링은 외부힘에 의한 변형 후 초기형태로의 복원을 보장함으로써, 복잡한 계산과정 없이 간접적으로 객체의 볼륨유지 효과를 제공하고 변형의 불안전성을 제거한다.