• The Transactions of the Korea Information Processing Society
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• v.3 no.2
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• pp.407-415
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• 1996

This paper introduces two schemes to improve the frame buffer access bandwidth. The first scheme suggests a rasterizer called SBUFRE that has Span Z Buffer and Span Z＆ Color Buffer within a rasterizer. The second scheme suggests a ZDRAM that has Z-value comparator within the DRAM. These schemes are to convert read- modify-write Z buffer compare into single write only operation that improves approximately 50% frame buffer access bandwidth.

• Journal of Digital Contents Society
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• v.8 no.1
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• pp.85-91
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• 2007

This paper proposes a new hybrid anti-aliasing method for reducing aliasing appearing on an implicit surface using the point sampling. The hybrid anti-aliasing method is a method that finds differences in the values of pixel shown in Z-buffers for an implicit surface and thereby uses each of three types of Z-buffer. After determining the level of differences, it expresses a 3 dimensional object by using a multi Z-buffer if the level is severe, a double Z-buffer for a middle level, and only the original Z-buffer for a negligible difference. In comparison with the existing method in which multi Z-buffers have been entirely used for enhancing the anti-aliasing effect, the hybrid anti-aliasing method is an efficient method demonstrating an effect similar to the one using a multi Z-buffer while reducing the number of Z-buffers to be used.

• Journal of Digital Contents Society
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• v.9 no.2
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• pp.363-369
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• 2008

In this paper, we have proposed 3D shape reconstruction using superquadrics and single z-buffer Constructive Solid Geometry (CSG) rendering algorithm. Superquadrics can obtain various 3D model using 11 parameters and both superquadrics and deformed-superquadrics play a role of primitives which are consisted of CSG tree. In addition, we defined some effective equations using z-buffer algorithm and stencil buffer for synthesizing 3D model. Using this proposed algorithm, we need not to consider the coordinate of each 3D model because we simply compare the depth value of 3D model.

• Korean Journal of Computational Design and Engineering
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• v.8 no.2
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• pp.65-74
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• 2003

For virtual reality, virtual manufacturing system, or simulation based design, we need to visualize very large and complex 3D models which are comprising of very large number of polygons. To overcome the limited hardware performance and to attain smooth realtime visualization, there have been many researches about algorithms which reduce the number of polygons to be processed by graphics hardware. One of these algorithms, occlusion culling is a method of rejecting the objects which are not visible because they are occluded by other objects, and then passing only the visible objects to graphics hardware. Existing occlusion culling algorithms have some shortcomings such as the required long preprocessing time, the limitation of occluder shape, or the need for special hardware implementation. In this study, an efficient occlusion culling algorithm is proposed. The proposed algorithm reads and analyzes Z-buffer of graphics hardware using Microsoft DirectX, and then determines each object's visibility. This proposed algorithm can speed up visualization by reading Z-buffer using DirectX which can access hardware directly compared to OpenGL, by reading only the region to which each object is projected instead of reading the whole Z-Buffer, and the proposed algorithm can perform more exact visibility test by using simplified model instead of using bounding box. For evaluation, the proposed algorithm was applied to very large polygonal models. And smooth realtime visualization was attained.

• Journal of Korea Multimedia Society
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• v.9 no.1
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• pp.41-50
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• 2006

This paper aims to improve the efficiency of a 3D-graphic software engine in a PDA platform and the performance of a rasterizer. There are many problems in implementing a software engine in a mobile platform, due to its relatively weak processing power. Taking the advantages and complementing weaknesses of the depth-sort algorithm and the Z-buffer algorithm, we implemented an adaptive Z-buffer algorithm and proved its performance on several PDA platforms. Our algorithm was evaluated to have midway speed compared with two conventional algorithms. It also removed reversal errors in comparison with the depth-sort algorithm.

• Proceedings of the Korean Information Science Society Conference
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• 1999.10b
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• pp.512-514
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• 1999

효율적인 물체인식을 위해서는 물체의 형상특징을 직선적으로 기술할 수 있는 체적소 기반 물체 표현 방법이 필요하다. 본 논문에서는 몇 개의 계수를 가지고 3차원 정보를 효율적으로 표현할 수 있는 superquadric을 이용하여 기본적인 3차원 물체를 모델링 한다. 그리고 보다 복잡하고 정교한 물체의 표현을 위해서 변형된 superquadric을 함께 이용한다. 이렇게 만들어진 개개의 3차원 모델에 z-buffer 알고리즘을 적용하여 하나의 완전한 3차원 물체로 표현하는 방법을 제시하고 실험을 통해 그 유용성을 입증하였다.

• Journal of Korea Multimedia Society
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• v.7 no.1
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• pp.44-53
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• 2004

This paper aims at presenting high quality at low resolution apply by a new antialiasing method for voxelized implicit surfaces. Implicit surfaces create a unique type of 3D-modeling. Some use of implicit surfaces are scientific and medical visualization, animation, medical simulation and interactive modeling. One of previous antialiasing methods for implicit surfaces presented by raytracing or texture mapping is making use of a stochastic sampling. But this method requires more calculation time and costs which is caused by complicated and difficult implicit functions. In the meanwhile, voxelized implicit surfaces generally use high resolution for good quality images but it costs to generate. In order to this problem, this paper suggests a shifted double Z-buffer which is very simple, more efficient and easy. Tn addition, there are applied box-filter and tent-filter to the double Z-buffer antialiasing method for better images. For results this method generate high quality image and it is easy to apply to various filters and is able to extend to multi Z-buffer.

• Journal of KIISE:Computer Systems and Theory
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• v.27 no.1
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• pp.13-22
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• 2000

We present a method that enhances the rendering speed of z-buffer algorithm using temporal coherence between two contiguous frames on fixed viewing conditions. Conventional z-buffer algorithm stores depth value for each pixel on a view plane while rendering some polygons, then it determines the visibility of the remaining polygons based on the stored depth values. If we can get color and depth information for some polygons without rendering, it is possible to generate an image by rendering only the remaining ones. In case of high frame rate, we can find the fact that sets of static polygons of the two contiguous frames are almost the same. This temporal coherence enables us to get the color and depth information of static polygons efficiently. Our algorithm stores color and depth information of static polygons and reuses it for generating the next frame. This method can be easily implemented since it does not require complex data structure and modification for conventional z-buffer algorithm. Also it is adequate for hardware implementation.

• Journal of the Korea Computer Graphics Society
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• v.6 no.1
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• pp.29-36
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• 2000

In this work, we propose ZF-buffer algorithm in order to accelerate the intersection test of ray-tracing algorithm. ZF-buffer is used in the preprocessing of ray-tracing and records the pointer that points to a parent face of a depth value(z value) of an object determined in Z-buffer. As a result, the face which intersects with the first ray can be determined easily by using the pointer stored in F-buffer. Though ZF-buffer and vista-buffer resemble each other, the difference between the two methods is that what ZF-buffer records is not bounding volume but the pointer of a displayable face. We applied the ZF-buffer algorithm for the first ray to Utah teapot which consists of 9216 polygons. By comparing the elapse time of our method with vista-buffer algorithm, we can acquire improvement in speed that it is 3 times faster than vista-buffer algorithm. We expanded our algorithm to the second ray.

• Journal of Digital Contents Society
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• v.5 no.3
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• pp.176-179
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• 2004

Superquadrics can represent various and complex 3D object with only wome parameters(size, position, deformation etc). So if we use both superquadrics and deformed superquadrics, we can reoresent more realistic 3D object which are existed in real world. In this paper we use the Z-buffer algorithm and stencil buffer together because this is very useful when the wuperquadric primitives are combined. The fundamental ideas are illustrated with a number of tables and figures.