• Journal of KIISE:Computer Systems and Theory
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• v.34 no.5_6
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• pp.228-237
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• 2007

displacement mapping enables us to add realistic details to polygonal meshes without changing geometry. We present a real-time artifacts-free inverse displacement mapping method. In each pixel, we construct a ray and trace the ray through the displacement map to find an intersection. To skip empty regions safely, we traverse the image pyramid of displacement map in top-down order. Furthermore, when the displacement map is enlarged, intersection with bilinear interpolated displacement map can be found. When the displacement map is at distance, our method supports mipmap-like prefiltering to enhance image quality and speed. Experimental results show that our method can produce correct images even at grazing view angles. Rendering speed of a test scene is over hundreds of frames per second and the influence of resolution of displacement map to rendering speed is little. Our method is simple enough to be added to existing virtual reality systems easily.

• Journal of the Korea Computer Graphics Society
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• v.21 no.3
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• pp.27-35
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• 2015

This study presents a volume rendering method using ambient occlusion which is one of global illumination methods. By considering the volume density distribution as normal distribution, ambient occlusion can be calculated at real-time speed regardless of modification of opacity transfer function. We calculate and store the averages and standard deviations of densities in a block centered at each voxel in pre-processing time. In rendering process, we determine the illumination value by estimating the nearby opacity. We generalized theoretical model and generated better quality images improving our previous research. In detail, various shapes of transfer function can be used due to the proposed equation model. Moreover, we introduced a multi-range model to give nearer objects more weight. As the result, more realistic volume rendering image can be generated at real-time speed by mixing local and ambient occlusion shading.

• Journal of Korea Multimedia Society
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• v.9 no.8
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• pp.1045-1053
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• 2006

We introduce a new method of painterly rendering. Instead of using the gradient direction of the source image to generate a brush stroke, we extract regions that can be drawn in one stroke using MHN filtering followed by identification of connected components, and make a brush stroke from each, based on an approximation to the medial axis. This method results in realistic-looking brush strokes of varying width that have an irregular directions where necessary.

• Journal of the Korea Computer Graphics Society
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• v.13 no.1
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• pp.7-14
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• 2007

In this paper we present an illumination model for rendering realistic stained glass. This techniques simulates the phenomenon of stained glass in real world by applying important optical component of the stained glass to the rendering algorithm. The optics for stained glass involves three basic physical mechanisms. First, diffuse light and highlight contribute to the brightness of stained glass which is typically white and changes along with the light source and the view position. Next, Fresnel refraction dominates the amount of refracted (transmitted) light. Finally, we express volume absorption occurs in all stained glass. Then, the rendered stained glass images achieve excellent realism.

• Journal of Korea Multimedia Society
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• v.10 no.2
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• pp.187-199
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• 2007

The purpose of painterly rendering is to express real painting work from input image. For expression of real pain ting impression, drawing condition is one of main element. In this paper, we propose new algorithm for using density of edges. Drawing condition of new algorithm uses color difference and density of edges. And for finding next position from current position, we used dynamic grid. We did direction interpolation for coherence direction. Also using various texture brush, we express the feel of a material effective. We show results of images rendered more realistic oil painting effect, and discuss long-term goals for more effective result.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.12 no.12
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• pp.5936-5954
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• 2018

Eight out of the top ten the largest technology companies in the world are involved in some way with the coming mobile VR revolution since Facebook acquired Oculus. This trend has allowed the technology related with mobile VR to achieve remarkable growth in both academic and industry. Therefore, the importance of reproducing the acoustic expression for users to experience more realistic is increasing because auditory cues can enhance the perception of the complicated surrounding environment without the visual system in VR. This paper presents a audio downmixing system for auralization based on hardware, a stage of sound rendering pipelines that can reproduce realiy-like sound but requires high computation costs. The proposed system is verified through an FPGA platform with the special focus on hardware architectural designs for low power and real-time. The results show that the proposed system on an FPGA can downmix maximum 5 sources in real-time rate (52 FPS), with 382 mW low power consumptions. Furthermore, the generated 3D sound with the proposed system was verified with satisfactory results of sound quality via the user evaluation.

• 한국HCI학회:학술대회논문집
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• 2006.02a
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• pp.1113-1119
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• 2006

본 논문에서는 광고나 포스터제작에 사용될 수 있는 이미지 모자이크 기법을 소개한다. 모자이크는 임의의 개수의 셀로 하나의 전체 이미지를 표현하는 기법이다. 이중 포토 모자이크는 사진의 조합으로 새로운 사진을 생성한다. 이는 만들고자 하는 영상을 격자를 이용해 나누고 해당 격자에 최적의 이미지를 영상 DB 로부터 찾아 격자를 채움으로써 하나의 이미지 모자이크를 생성한다. 본 논문에서는 하나의 단위 이미지(색이 할당되지 않고 형태만 갖는 영상)를 사용하여 경계로 구분된 특정 영역을 채워나감으로써 하나의 추상화된 예술적 모자이크 영상을 생성하는 알고리즘을 소개한다. 하나의 단위 이미지는 회전, 이동을 통해 다양하게 변할 수 있으며 입력영상의 그래디언트의 방향과 에지정보를 이용해 해당영역을 채우게 된다. 이를 위해서 에지를 넘어서지 않도록 단위 이미지를 변환시키며 최적의 위치를 찾게된다. 또한 입력영상의 색상이나 임의의 색상이나 특정 색상테이블을 이용해 단위 이미지에 색상을 할당함으로써 만들고자 하는 입력영상과 비슷한 모양을 갖거나 형태만을 유지한 추상화된 모자이크 영상 생성이 가능하다.

• Journal of the Korea Computer Graphics Society
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• v.2 no.1
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• pp.15-23
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• 1996

Bump mapping is an elegant rendering technique to simulate wrinkled surfaces such as bark, which enables to produce more realistic image than texture-mapped one. This paper presents a new algorithm for bump mapping along with a hardware architecture to run our algorithm in real-time. The proposed approach is more efficient than previous one, and in particular, our hardware architecture is simpler to implement.

• Journal of Korea Multimedia Society
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• v.17 no.7
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• pp.906-914
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• 2014

There are many studies to create realistic paint effects and the research area still has attracted attention in these days. However, the consideration for the characteristics of the real paint effects from the point of viewers is not enough. In this paper, we extract the important paint features and survey the importance values. Based on the survey results, we suggest a new paint system. The paint system utilizes the paint simulation that reflects viscoelasticity and mixing suggested by You et al. (2013) and proposes the paint rendering method that represents the details of a paint, a solvent, and pigments. We survey the quality of our results and prove that our paint system is superior to the previous studies.

• 한국HCI학회:학술대회논문집
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• 2007.02b
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• pp.452-457
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• 2007

본 논문은 연극이나 영화 애니메이션의 기획단계(Pre-Production)의 최종단계이자 시나리오를 영상으로 표현하는 첫 단계인 스토리보드를 기획의도와 연출 방향을 효과적으로 반영하는 방법에 대한 논문이다. 일반적으로 스토리보드라 한다면 필름화 할 동작들을 분할하여 그림이나 사진으로 연결시켜 놓고 그에 해당하는 짧은 설명을 써놓은 것으로 생각하는 경우가 많다. 하지만 정적인 그림과 사진으로서는 근래의 영화에서 보여지는 역동적인 장면들을 표현하기 어려우므로 최근 애니매틱스(animatics)라 불리는 3D와 2D를 이용한 스토리보드를 사용하는 사례가 늘고 있다. 이에 본 논문은 연구를 통하여 애니메틱스의 현황과 사례를 살펴보고 좀더 감각적이고 직관적인 스토리보드의 제작 방법을 제시하고자 한다.