• Journal of Korea Game Society
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• v.13 no.2
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• pp.99-110
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• 2013

As volume rendering has been applied for computer game, the visualization of volume data with surface data in one scene has been required. Though a hybrid rendering of volume and surface data have been developed using the GPGPU functionality, computer games which run on low-level hardware are difficult to perform the hybrid rendering. In this paper, we propose a new hybrid rendering based on DirectX 9.0 and general hardware. We generate the layered depth images from surface data using a new method to reduce the depth complexity and generation time. Then, we perform the hybrid rendering using the layered depth images. In the rendering process, we suggest a new method to transform the coordinate system from a surface coordinate to a volume coorinate and propose an accelerated rendering technique. As the result, we can perform volume-surface hybrid rendering in an efficient way.

• 한국전산유체공학회:학술대회논문집
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• 1999.11a
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• pp.158-162
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• 1999

This thesis presents applications of three dimensional visualization technique based on shear-warp volume rendering to medical information. Volume rendering is compared to surface rendering and acceleration technique is also presented. The presented rendering techniques by using three-dimensional arrays of data are a widely used representation for computational fluid dynamics and geological structures as well as medical information.

• Korean Journal of Computational Design and Engineering
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• v.13 no.6
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• pp.469-477
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• 2008

Physically-based rendering is an image synthesis technique based on simulation of physical interactions between light and surface materials. Since generated images are highly photorealistic, physically-based rendering has become an indispensable tool in advanced design visualization for manufacturing and architecture as well as in film VFX and animations. Especially, BRDF (bidirectional reflectance distribution function) is critical in realistic visualization of materials since it models how an incoming light is reflected on the surface in terms of intensity and outgoing angles. In this paper, we introduce techniques to represent BRDF as B-spline volumes and to utilize them in physically-based rendering. We show that B-spline volume BRDF (BVB) representation is suitable for measured BRDFs due to its compact size without quality loss in rendering. Moreover, various CAGD techniques can be applied to B-spline volume BRDFs for further controls such as refinement and blending.

• Journal of Biomedical Engineering Research
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• v.21 no.4
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• pp.433-439
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• 2000

Volume rendering is a powerful tool for visualizing sampled scalar values from 3D data without modeling geometric primitives to the data. The volume rendering can describe the surface-detail of a complex object. Owing to this characteristic. volume rendering has been used to visualize medical data. The size of volume data is usually too big to handle in real time. Recently, various volume rendering algorithms have been proposed in order to reduce the rendering time. However, most of the proposed algorithms are not proper for fast rendering of large non-coded volume data. In this paper, we propose a block-based fast volume rendering algorithm using a shear-warp factorization for non-coded volume data. The algorithm performs volume rendering by using the organ segmentation data as well as block-based 3D volume data, and increases the rendering speed for large non-coded volume data. The proposed algorithm is evaluated by rendering 3D X-ray CT body images and MR head images.

• Journal of International Society for Simulation Surgery
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• v.1 no.1
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• pp.27-31
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• 2014

In this paper, an overview of segmentation and 3D visualization methods are presented. Commonly, the two kinds of methods are used to visualize organs and vessels into 3D from medical images such as CT(A) and MRI - Direct Volume Rendering (DVR) and Iso-surface Rendering (IR). DVR can be applied directly to a volume. It directly penetrates through the volume while it determines which voxels are visualizedbased on a transfer function. On the other hand, IR requires a series of processes such as segmentation, polygonization and visualization. To extract a region of interest (ROI) from the medical volume image via the segmentation, some regions of an object and a background are required, which are typically obtained from the user. To visualize the extracted regions, the boundary points of the regions should be polygonized. In other words, the boundary surface composed of polygons such as a triangle and a rectangle should be required to visualize the regions into 3D because illumination effects, which makes the object shaded and seen in 3D, cannot be applied directly to the points.

• 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.

• 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.

• 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.

• 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.

• Journal of KIISE:Computer Systems and Theory
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• v.27 no.5
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• pp.441-449
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• 2000

Binary volume data has its widespread use in the application of color volume rendering and surgical simulation system where gray-scale volume is inappropriate. For the efficient representation of binary volume, this paper proposes a new data structure - the Slice-based Binary Shell (SBS) - along with its rendering algorithm. Since SBS stores the minimal set of surface voxels in slice order and supports the direct computation of voxel coordinates, it shows high efficiency for rendering multiple objects. The rendering algorithm of SBS running on a PC with no specialized hardware renders more than one hundred binary objects in a second.