• Title/Summary/Keyword: Volume Rendering

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Adaptive B-spline volume representation of measured BRDF data for photorealistic rendering

  • Park, Hyungjun;Lee, Joo-Haeng
    • Journal of Computational Design and Engineering
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    • v.2 no.1
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    • pp.1-15
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    • 2015
  • Measured bidirectional reflectance distribution function (BRDF) data have been used to represent complex interaction between lights and surface materials for photorealistic rendering. However, their massive size makes it hard to adopt them in practical rendering applications. In this paper, we propose an adaptive method for B-spline volume representation of measured BRDF data. It basically performs approximate B-spline volume lofting, which decomposes the problem into three sub-problems of multiple B-spline curve fitting along u-, v-, and w-parametric directions. Especially, it makes the efficient use of knots in the multiple B-spline curve fitting and thereby accomplishes adaptive knot placement along each parametric direction of a resulting B-spline volume. The proposed method is quite useful to realize efficient data reduction while smoothing out the noises and keeping the overall features of BRDF data well. By applying the B-spline volume models of real materials for rendering, we show that the B-spline volume models are effective in preserving the features of material appearance and are suitable for representing BRDF data.

TF color mapping for direct volume rendering with CNN (직접 볼륨 렌더링을 위한 CNN 기반 TF 색상 매핑)

  • Kim, Seokyeon;Jang, Yun
    • Journal of the Korea Computer Graphics Society
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    • v.27 no.5
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    • pp.25-32
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    • 2021
  • Direct Volume Rendering(DVR) renders by projecting data into a two-dimensional space without calculating the volume surfaces. In DVR, the transfer function(TF) assigns light properties such as color and transparency to the volume. However, it takes a long time for beginners to manipulate TF to understand volume data and assign colors. This paper proposes an approach to colorize the volume using sample images for intuitive volume rendering. We also discuss color extraction methods using K-means clustering.

Improvement Depth Perception of Volume Rendering using Virtual Reality (가상현실을 통한 볼륨렌더링 깊이 인식 향상)

  • Choi, JunYoung;Jeong, HaeJin;Jeong, Won-Ki
    • Journal of the Korea Computer Graphics Society
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    • v.24 no.2
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    • pp.29-40
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    • 2018
  • Direct volume rendering (DVR) is a commonly used method to visualize inner structures in 3D volumetric datasets. However, conventional volume rendering on a 2D display lacks depth perception due to dimensionality reduction caused by ray casting. In this work, we investigate how emerging Virtual Reality (VR) can improve the usability of direct volume rendering. We developed real-time high-resolution DVR system in virtual reality, and measures the usefulness of volume rendering with improved depth perception via a user study conducted by 38 participants. The result indicates that virtual reality significantly improves the usability of DVR by allowing better depth perception.

An efficient space-leaping method using double leaping (이중 도약을 이용한 효율적인 공간 도약법)

  • 이정진;신병석;신영길
    • Journal of KIISE:Computer Systems and Theory
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    • v.30 no.3_4
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    • pp.109-116
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    • 2003
  • Space leaping is one of accelerated image-order volume rendering. This method accelerates rendering speed by finding and leaping the empty space. Although its rendering speed is very fast, it takes long pre-processing time to make the data structure to leap the space. In this paper we propose the look-ahead sampling algorithm to double the leaping distance comparing with previous approaches. This algorithm reduces the preprocessing time to make the distance map without significant changes of rendering time. Also, it accelerates the rendering time.

Exploiting Programmable Shaders in Hardware-Assisted Volume Rendering (PC용 그래픽스 가속기의 쉐이더 기능을 이용한 볼륨 렌더링)

  • Im, In-Seong;Gang, Byeong-Gwon
    • Journal of the Korea Computer Graphics Society
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    • v.8 no.2
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    • pp.23-29
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    • 2002
  • In this paper, we describe an implementation technique that extends the classification and shading capabilities offered by previously reported hardware-assisted volume rendering algorithms. In designing our rendering scheme, we exploited the programmable shader technology supported by the latest consumer PC graphics hardware. Our direct volume rendering technique enables to simultaneously display up to four materials, and to dynamically control gradient magnitude to emphasize or de-emphasize surface boundaries. It can easily create lighting effects such as light source attenuation, depth cueing, and multiple light sources that were often difficult to realize in previous hardware-assisted volume rendering.

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A Fast Volume Rendering Algorithm for Virtual Endoscopy

  • Ra Jong Beom;Kim Sang Hun;Kwon Sung Min
    • Journal of Biomedical Engineering Research
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    • v.26 no.1
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    • pp.23-30
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    • 2005
  • 3D virtual endoscopy has been used as an alternative non-invasive procedure for visualization of hollow organs. However, due to computational complexity, this is a time-consuming procedure. In this paper, we propose a fast volume rendering algorithm based on perspective ray casting for virtual endoscopy. As a pre-processing step, the algorithm divides a volume into hierarchical blocks and classifies them into opaque or transparent blocks. Then, in the first step, we perform ray casting only for sub-sampled pixels on the image plane, and determine their pixel values and depth information. In the next step, by reducing the sub-sampling factor by half, we repeat ray casting for newly added pixels, and their pixel values and depth information are determined. Here, the previously obtained depth information is utilized to reduce the processing time. This step is recursively performed until a full-size rendering image is acquired. Experiments conducted on a PC show that the proposed algorithm can reduce the rendering time by 70- 80% for bronchus and colon endoscopy, compared with the brute-force ray casting scheme. Using the proposed algorithm, interactive volume rendering becomes more realizable in a PC environment without any specific hardware.

Selective Rendering of Specific Volume using a Distance Transform and Data Intermixing Method for Multiple Volumes (거리변환을 통한 특정 볼륨의 선택적 렌더링과 다중 볼륨을 위한 데이타 혼합방법)

  • Hong, Helen;Kim, Myoung-Hee
    • Journal of KIISE:Computer Systems and Theory
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    • v.27 no.7
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    • pp.629-638
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    • 2000
  • The main difference between mono-volume rendering and multi-volume rendering is data intermixing. In this paper, we first propose a selective rendering method for fast visualizing specific volume according to the surface level and then present data intermixing method for multiple volumes. The selective rendering method is to generate distance transformed volume using a distance transform to determine the minimum distance to the nearest interesting part and then render it. The data intermixing method for multiple volumes is to combine several volumes using intensity weighted intermixing method, opacity weighted intermixing method, opacity weighted intermixing method with depth information and then render it. We show the results of selective rendering of left ventricle and right ventricle generated from EBCT cardiac images and of data intermixing for combining original volume and left ventricular volume or right ventricular volume. Our method offers a visualization technique of specific volume according to the surface level and an acceleration technique using a distance transformed volume and the effective visual output and relation of multiple images using three different intermixing methods in three-dimensional space.

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Volume Haptic Rendering Algorithm for Realistic Modeling (실감형 모델링을 위한 볼륨 햅틱 렌더링 알고리즘)

  • Jung, Ji-Chan;Park, Joon-Young
    • Korean Journal of Computational Design and Engineering
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    • v.15 no.2
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    • pp.136-143
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    • 2010
  • Realistic Modeling is to maximize the reality of the environment in which perception is made by virtual environment or remote control using two or more senses of human. Especially, the field of haptic rendering, which provides reality through interaction of visual and tactual sense in realistic model, has brought attention. Haptic rendering calculates the force caused by model deformation during interaction with a virtual model and returns it to the user. Deformable model in the haptic rendering has more complexity than a rigid body because the deformation is calculated inside as well as the outside the model. For this model, Gibson suggested the 3D ChainMail algorithm using volumetric data. However, in case of the deformable model with non-homogeneous materials, there were some discordances between visual and tactual sense information when calculating the force-feedback in real time. Therefore, we propose an algorithm for the Volume Haptic Rendering of non-homogeneous deformable object that reflects the force-feedback consistently in real time, depending on visual information (the amount of deformation), without any post-processing.

Volume Rendering Technique for 3-D Visualization and Its Performance Improvements (물체의 3차원적 도시를 위한 입체묘사기법의 성능향상 및 그 응용)

  • Lee, Min-Seop;Cheon, Gang-Uk;Ra, J.B
    • Journal of Biomedical Engineering Research
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    • v.12 no.2
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    • pp.79-88
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    • 1991
  • Semi-transparent volume rendering technique can provide 3-D visualization well by voxel level Processing and alleviate segmentation arf, ifacts compared wish the surface rendering technique. In this Paper, we consider several new schemes which can improve she Perform ance of volume rendering. A directional interpolation method is proposed to reduce the artifact due to the anisotrophic resolution in X-ray CT data. The computation time for rendering is shortened by using the depth information of the 3-D object. And also, we reduce the quantization artifacts in the rendering by introducing the opacity-dependent sampling interval to sampling in ray-tracing.

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Fast Ambient Occlusion Volume Rendering using Local Statistics (지역적 통계량을 이용한 고속 환경-광 가림 볼륨 가시화)

  • Nam, Jinhyun;Kye, Heewon
    • Journal of Korea Multimedia Society
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    • v.18 no.2
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    • pp.158-167
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    • 2015
  • This study presents a new method to improve the speed of high quality volume rendering. We improve the speed of ambient occlusion which is one of the global illumination techniques used in traditional volume visualization. Calculating ambient occlusion takes much time because it determines an illumination value of a sample by integrating opacities of nearby samples. This study proposes an improved method for this by using local statistics such as averages and standard deviations. We calculate local statistics for each volume block, a set of nearby samples, in pre-processing time. In the rendering process, we efficiently determine the illumination value by assuming the density distribution as a normal distribution. As the results, we can generate high quality images that combine ambient occlusion illumination with local illumination in real time.