• 한국HCI학회:학술대회논문집
• /
• 2009.02a
• /
• pp.719-724
• /
• 2009

Fur rendering is difficult in that there are huge numbers of objects and it takes so much time. The previous method considers fur as cylinder, transforms it into 2D ribbon, triangulates and commits rendering. But this method has problem like under sampling and takes rendering time so long. To resolve these shortcuts we proposed new algorithm. We divide fur into thick and thin fur and we applied adaptive rendering methods for each type of fur. Also we can perform an effective rendering according to the proposed rendering framework.

• Journal of Computational Design and Engineering
• /
• v.2 no.1
• /
• pp.1-15
• /
• 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
• /
• v.27 no.1
• /
• pp.6-13
• /
• 2006

Ultrasound visualization is a typical diagnosis method to examine organs, soft tissues and fetus data. It is difficult to visualize ultrasound data because the quality of the data might be degraded by artifact and speckle noise, and gathered with non-linear sampling. Rendering speed is too slow since we can not use additional data structures or procedures in rendering stage. In this paper, we use several visualization methods for fast rendering of ultrasound data. First method, denoted as adaptive ray sampling, is to reduce the number of samples by adjusting sampling interval in empty space. Secondly, we use early ray termination scheme with sufficiently wide sampling interval and low threshold value of opacity during color compositing. Lastly, we use bilinear interpolation instead of trilinear interpolation for sampling in transparent region. We conclude that our method reduces the rendering time without loss of image quality in comparison to the conventional methods.

• Journal of Digital Contents Society
• /
• v.9 no.3
• /
• pp.509-516
• /
• 2008

We propose the Hybrid Rendering model to support multi-resolution for computer graphics. LOD method for computer graphics system considering performance of device environment and end-user preference usually adopts mesh resolution, mipmap in texture rendering, or oct-tree data structure in ray tracing. The hybrid rendering model, as a local shading model combining Gouraud shading model and a flat shading model, applies a proper shading method to each of polygons consisting of an object. This method can be an effective alternative to reduce real-time rendering time so that it can be utilized in real time adaptive service of computer graphic contents among various device environments under ubiquitous environments.

• Journal of Digital Contents Society
• /
• v.9 no.4
• /
• pp.771-778
• /
• 2008

A Device performance analyzing method for appropriate level in hybrid rendering model is suggested. In recent research, we proposed a hybrid rendering model which is applying a proper shading method to each of polygons consisting of an object. The number of polygon for Gouraud shading and that for flat shading should be considered according to a current device performance and system environments. Therefore, this paper suggests the method to calculate automatically a proper resolution of a mesh of object and a proper level of mixture between Gouraud and a flat shading, considering a current device performance and a preference of end-user. The rendering model is so simple that it can be an efficient replacement to reduce a real-time rendering time since it provides automatically multi-level of rendering resolution to an executing environments. Moreover, it can be adopted in real-time adaptive service for 3D graphic contents like a graphic game under various device environments.

• The KIPS Transactions:PartA
• /
• v.10A no.5
• /
• pp.425-432
• /
• 2003

This paper presents an EMR(Electronic Medical Record) chart for efficient PDA through the quad tree image rendering based on the mobile. Using the intermediate image space algorithm instead of the final one for volume rendering, we have solved the probems of th eholes coming from the point-to-point to mapping. The quad-tree based on the delta-tree efficiently represents volume expressions and results in higher compression effects. With the volume rendering, we can decrease the rendering time and get a higher quality and efficiency for PDA through image based rendering.

• Journal of KIISE:Computer Systems and Theory
• /
• v.33 no.11
• /
• pp.853-858
• /
• 2006

In this paper, we propose a practical method for hardware-accelerated rendering of the depth image-based representation(DIBR) of 3D graphic object using graphic processing unit(GPU). The proposed method overcomes the drawbacks of the conventional rendering, i.e. it is slow since it is hardly assisted by graphics hardware and surface lighting is static. Utilizing the new features of modem GPU and programmable shader support, we develop an efficient hardware-accelerating rendering algorithm of depth image-based 3D object. Surface rendering in response of varying illumination is performed inside the vertex shader while adaptive point splatting is performed inside the fragment shader. Experimental results show that the rendering speed increases considerably compared with the software-based rendering and the conventional OpenGL-based rendering method.

• International Journal of CAD/CAM
• /
• v.6 no.1
• /
• pp.139-148
• /
• 2006

Catmull-Clark subdivision scheme provides a powerful method for building smooth and complex surfaces. But the number of faces in the uniformly refined meshes increases exponentially with respect to subdivision depth. Adaptive tessellation reduces the number of faces needed to yield a smooth approximation to the limit surface and, consequently, makes the rendering process more efficient. In this paper, we present a new adaptive tessellation method for general Catmull-Clark subdivision surfaces. Different from previous control mesh refinement based approaches, which generate approximate meshes that usually do not interpolate the limit surface, the new method is based on direct evaluation of the limit surface to generate an inscribed polyhedron of the limit surface. With explicit evaluation of general Catmull-Clark subdivision surfaces becoming available, the new adaptive tessellation method can precisely measure error for every point of the limit surface. Hence, it has complete control of the accuracy of the tessellation result. Cracks are avoided by using a recursive color marking process to ensure that adjacent patches or subpatches use the same limit surface points in the construction of the shared boundary. The new method performs limit surface evaluation only at points that are needed for the final rendering process. Therefore it is very fast and memory efficient. The new method is presented for the general Catmull-Clark subdivision scheme. But it can be used for any subdivision scheme that has an explicit evaluation method for its limit surface.

• Journal of KIISE:Computer Systems and Theory
• /
• v.30 no.11
• /
• pp.655-662
• /
• 2003

In some volume visualization fields such as medical imaging, anisotropic volume data are more common than isotropic ones. In this paper, we propose an efficient rendering method for anisotropic volume data, which directly computes the intensity of intermediate samples by interpolating the intensity of two corresponding voxels on consecutive slices. Unlike density interpolation method, it does not require a preprocessing step for generating intermediate slices or additional memory for storing them. Additionally, we propose an adaptive intermediate voxel insertion method that avoids overblurring on object surfaces. This may occur when we render high frequency areas using the intensity interpolation method. Using these methods, we can improve the rendering speed without sacrificing image quality.

• Journal of Broadcast Engineering
• /
• v.27 no.2
• /
• pp.216-227
• /
• 2022

The MPEG-I (Immersive) group is working on a standardization project for immersive video that provides 6 degrees of freedom (6DoF). The MPEG Immersion Video (MIV) standard technology is intended to provide limited 6DoF based on depth map-based image rendering (DIBR) technique. Many efficient coding methods have been suggested for MIV, but efficient transmission strategies have received little attention in MPEG-I. This paper proposes group-based adaptive rendering method for immersive video streaming. Each group can be transmitted independently using group-based encoding, enabling adaptive transmission depending on the user's viewport. In the rendering process, the proposed method derives weights of group for view synthesis and allocate high quality bitstream according to a given viewport. The proposed method is implemented through the Test Model for Immersive Video (TMIV) test model. The proposed method demonstrates 17.0% Bjontegaard-delta rate (BD-rate) savings on the peak signalto-noise ratio (PSNR) and 14.6% on the Immersive Video PSNR(IV-PSNR) in terms of various end-to-end evaluation metrics in the experiment.