• Title/Summary/Keyword: Efficient Ray Casting

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Efficient Computation of Isosurface Curvatures on GPUs Based on the de Boor Algorithm (드 부어 알고리즘을 이용한 GPU에서의 효율적인 등가면 곡률 계산)

  • Kim, Minho
    • Journal of the Korea Computer Graphics Society
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    • v.23 no.3
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    • pp.47-54
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    • 2017
  • In this paper, we propose an improved curvature-based GPU (Graphics Processing Unit) isosurface ray-casting technique. Our method adopts the fast evaluation method proposed by Sigg et al. [1] to find the isosurface, but replaces the computation of the gradient and Hessian with the de Boor algorithm. In this way, we can reduce the number of additional texture fetches from 84 to 27 thus improving the performance by up to ${\approx}30%$, depending on the platforms.

High-quality Shear-warp Volume Rendering Using Efficient Supersampling and Pre-integration Technique (효율적인 수퍼샘플링과 선-적분을 이용한 고화질 쉬어-왑 분해 볼륨 렌더링)

  • Kye, Hee-Won;Kim, Tae-Young
    • Journal of Korea Multimedia Society
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    • v.9 no.8
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    • pp.971-981
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    • 2006
  • As shear-warp volume rendering is the fastest rendering method among the software based approaches, image quality is not good as that of other high-quality rendering methods. In this paper, we propose two methods to improve the image quality of shear-warp volume rendering without sacrificing computational efficiency. First, supersampling is performed in intermediate image space. We propose an efficient method to transform between volume and image coordinates at the arbitrary ratio. Second, we utilize pre-integrated rendering technique for shear-warp rendering. We propose new data structure called overlapped min-max map. Using this structure, empty space leaping can be performed so that we can maintain the rendering speed even though pre-integrated rendering is applied. Consequently, shear-warp rendering can generate high-qualify images comparable to those generated by the ray-casting without degrading speed.

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Efficient High Quality Volume Visualization Using Cardinal Interpolation (카디널 보간을 이용한 효율적인 고화질 볼륨 가시화)

  • Kye, Hee-Won
    • Journal of Korea Multimedia Society
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    • v.14 no.3
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    • pp.339-347
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    • 2011
  • As the volume visualization has been applied to render medical datasets, there has been a requirement to produce high quality images. Even though nice images can be generated by using previous linear filter, high order filter is required for better images. However, it takes much time for high order resampling, so that, overall rendering time is increased. In this paper, we perform high quality volume visualization using the cardinal interpolation. By enabling the empty space leaping which reduces the number of resampling, we achieve the efficient visualization. In detail, we divide the volume data into small blocks and leap empty blocks by referring the upper and lower bound value for each block. We propose a new method to estimate upper and lower bound value of for each block. As the result, we noticeably accelerated high quality volume visualization.

Preparation and Characterization of Chitosan/Cellulose Acetate Blend Film (키토산/셀룰로오스 아세테이트 복합필름의 제조와 특성)

  • Jung, Young-Jin;An, Byung-Jae;Choi, Hae-Wook;Kim, Hong-Sung;Lee, Young-Hee
    • Textile Coloration and Finishing
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    • v.19 no.4
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    • pp.10-17
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    • 2007
  • Chitosan(CS) and cellulose acetate(CA) composite films were prepared using formic acid as a cosolvent by casting, solvent evaporating and neutralization method. This study examines if the blending method, which uses formic acid as a cosolvent is efficient in improving the mechanical properties of CS film, especially wet strength and elongation. Formic acid is an effective cosolvent for the blend of CS and CA. Under wet condition, tensile strength and elongation of the composite films were obviously higher than those of the films made from pure CS. FTIR, DSC, and X-ray diffraction showed that the composite films exhibit a high level of compatibility and that strong interaction between the CS and CA was caused by intermolecular hydrogen bonding. The affinity series of composite film to transition metal ions are Cu(II) > Cd(II) > Cr(III). The adsorption of Cu((II) ion was shown to be highly pH sensitive.

High quality volume visualization using B-spline interpolation (B 스플라인 보간을 이용한 고화질 볼륨 가시화)

  • Shin, Yongha;Kye, Heewon
    • Journal of the Korea Computer Graphics Society
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    • v.22 no.3
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    • pp.1-9
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    • 2016
  • Linear interpolation is a basic sampling method for volume visualization. This method generates good images but sometimes it is inferior to our high expectation because it is encouraged to produce high quality images in the medical applications. In this paper, B spline based tri-cubic interpolation is used for the re-sampling step. The conventional B spline is an approximation method which does not cross control points so that we moved the control points and the curve crosses the original control points. In the rendering step, the empty space leaping is applicable to increase rendering speed. We have to calculate the maximum and minimum values for each block to detect empty space. The convex hull property of B spline enables the values of control points to be used as the maximum and minimum values. As a result, tri-cubic interpolated volume rendering is possible in interactive speed.

GPU-only Terrain Rendering for Walk-through (Walk-through를 지원하는 GPU 기반 지형렌더링)

  • Park, Sun-Yong;Oh, Kyoung-Su;Cho, Sung-Hyun
    • Journal of Korea Game Society
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    • v.7 no.4
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    • pp.71-80
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    • 2007
  • In this paper, we introduce an efficient GPU-based real-time rendering technique applicable to every kind of game. Our method, without an extra geometry, can represent terrain just with a height map. It makes it possible to freely go around in the air or on the surface, so we can directly apply it to any computer games as well as a virtual reality. Since our method is not based on any geometrical structure, it doesn't need special LOD policy and the precision of geometrical representation and visual quality absolutely depend on the resolution of height map and color map. Moreover, GPU-only technique allows the general CPU to be dedicated to more general work, and as a result, enhances the overall performance of the computer. To date, there have been many researches related to the terrain representation, but most of them rely on CPU or confmed its applications to flight simulation, Improving existing displacement mapping techniques and applying it to our terrain rendering, we completely ruled out the problems, such as cracking, poping etc, which cause in polygon-based techniques, The most important contributions are to efficiently deal with arbitrary LOS(Line Of Sight) and dramatically improve visual quality during walk-through by reconstructing a height field with curved patches. We suggest a simple and useful method for calculating ray-patch intersections. We implemented all these on GPU 100%, and got tens to hundreds of framerates with height maps a variety of resolutions$(256{\times}256\;to\;4096{\times}4096)$.

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