• Journal of Korea Multimedia Society
• /
• v.23 no.8
• /
• pp.903-914
• /
• 2020

In this paper, we present a novel algorithm to generate a 3D model of patient-specific orbital implant, which is finally produced by the 3D printer. Given CT (computed tomography) scan data of the defective orbital wall or floor, we compose the depth image of the defect site by using the depth buffering, which is a computer graphics technology. From the depth image, we compute the 3D surface which fills the broken part by interpolating the points around the broken part. By thickening the 3D surface, we get the 3D volume mesh of the orbital implant. Our algorithm generates the patient-specific orbital implant whose shape is accurately coincident to the broken part of the orbit. It provides the significant time efficiency for manufacturing the implant with supporting high user convenience.

• Proceedings of the Korea Concrete Institute Conference
• /
• 1996.04a
• /
• pp.270-274
• /
• 1996

Until recently pre & post-processing of finite element model has been heavily relied on expensive graphic peripheral devices. But today, with the aid of inexpensive microcomputers, very effective pre & postprocessor graphics has been developed. In this study, Pre & Post processor(MASSPRE, MASSPOST) of prediction analysis of thermal stress in mass concrete structure is developed. The developed pre & post processors are raise to the efficiency in making input data for the main program and analysis of the results produced by the main program. This MASSPOST presents a stress contour graph, volume slice, time-temperature history graph, time-stress history graph, etc.

• The Transactions of the Korean Institute of Electrical Engineers
• /
• v.38 no.8
• /
• pp.658-666
• /
• 1989

In this paper, an efficient algorithm for estimation volume and surface area and a reconstruction algorithm for 3-dimensional graphics are presented.In order to improve computing efficiency, the graph theory is utilized and the algorithm to obtain proper contour points is developed by considering several tolerances. Search for the contour points is limited by the change of curvature of cross sectional contour to provide efficiency in searching the minimum cost path. In computer simulation of these algorithms, the results show that, for the tolerance values of 1.001 and 1.002, the execution time reduced to 66%-80% and the error for the measured value is less than 3%. The reconstructed 3-dimensional images from the cross sections can be analyzed in many directions using the graphic scheme.

• Proceedings of the Korean Society of Computer Information Conference
• /
• 2022.01a
• /
• pp.373-376
• /
• 2022

본 논문에서는 삼각형 메쉬 기반에서 옷감 시뮬레이션(Cloth simulation)에서 계산양이 큰 자기충돌(Self-collision) 처리를 GPU기반으로 가속화시킬 수 있는 방법에 대해 소개한다. CUDA기반으로 병렬 최적화하기 위해 본 논문에서는 1)재귀적으로 계산하여 충돌판정을 하는 BVH(Bounding volume hierarchy) 트리를 GPU기반에서 효율적으로 빌드, 업데이트, 트리 순회하는 방법을 제안하고, 2)삼각형 메쉬 기반에서는 중복되는 프리미티브(Primitive) 충돌검사를 최소화하기 위해 R-Triangle기법을 GPU에서 최적화 시키는 방법을 소개한다. 결과적으로 본 논문에서 제안하는 기법은 GPU 환경에서 옷감 시뮬레이션의 자기충돌과 객체충돌 처리를 빠르고 효율적으로 처리할 수 있도록 하였고, 다양한 장면에서 실험한 결과 모든 결과에서 빠른 시뮬레이션 결과를 얻을 수 있었다.

• Journal of the Korea Computer Graphics Society
• /
• v.19 no.4
• /
• pp.1-11
• /
• 2013

In this paper, we represented the HTML5 webpage in 3D space for the 3D stereoscopic display by using CSS3 stylesheet; browser-based declarative contents, and proposed CSS Stereo 3DTV Profile. First, we suggested various webpage separation methods for reconstructing webpages in the 3D space effectively. Next, we suggested 3D view volume setting method by using extended CSS3 modules. And then, pre-processor converts sample contents which is written extended CSS stylesheet into the present CSS stylesheet for displaying in the webkit based browser. For the resulting stereoscopic images, we developed a rendering engine emulator which is implemented in JavaScript for simple display in the web browser, which produced dual images from virtual left and right-eyed cameras. And we have checked the sample contents displayed on the 3DTV.

• Journal of Digital Convergence
• /
• v.13 no.11
• /
• pp.331-336
• /
• 2015

The texture mapping used for the low-polygon models is one of the important workflows in the graphical representation of the 3D game. Only one hand painted texture is mapped on the surface of the 3D model and represents the color of the material and visual sense of touching by itself in that process. In the 3D game graphics, it is very important to visualize the textile sensation such as protruding and denting. It can be interpreted by the Gestalt Law to recognize a plane as a 3D sense of volume. Moreover, the concept of Affordance is necessary to recognize and perceive the textile sensation. It means visual recognizing of that relationship in the learning process. In this paper, The questionnaire survey targeting 3D game graphic designers is carried out. By analyzing the survey results, we suggest the important characteristic in the process of making hand painted texture.

• Journal of the Korea Computer Graphics Society
• /
• v.6 no.1
• /
• pp.29-36
• /
• 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 the Korea Computer Graphics Society
• /
• v.21 no.3
• /
• pp.36-45
• /
• 2015

It is important subject of research in engineering and natural science field that creating continuing high-definition image from very large volume data. The necessity of software that helps analyze useful information in data has improved by effectively showing visual image information of high resolution data with visualization technique. In this paper, we designed multi-platform visualization system based on client-server to analyze and express earth environment data effectively constructed with observation and prediction. The visualization server comprised of cluster transfers data to clients through parallel/distributed computing, and the client is developed to be operated in various platform and visualize data. In addition, we aim user-friendly program through multi-touch, sensor and have made realistic simulation image with image-based lighting technique.

• 한국HCI학회:학술대회논문집
• /
• 2007.02c
• /
• pp.306-317
• /
• 2007

We present an interactive and accurate collision detection algorithm for deformable, polygonal objects based on the streaming computational model. Our algorithm can detect all possible pairwise primitive-level intersections between two severely deforming models at highly interactive rates. In our streaming computational model, we consider a set of axis aligned bounding boxes (AABBs) that bound each of the given deformable objects as an input stream and perform massively-parallel pairwise, overlapping tests onto the incoming streams. As a result, we are able to prevent performance stalls in the streaming pipeline that can be caused by expensive indexing mechanism required by bounding volume hierarchy-based streaming algorithms. At run-time, as the underlying models deform over time, we employ a novel, streaming algorithm to update the geometric changes in the AABB streams. Moreover, in order to get only the computed result (i.e., collision results between AABBs) without reading back the entire output streams, we propose a streaming en/decoding strategy that can be performed in a hierarchical fashion. After determining overlapped AABBs, we perform a primitive-level (e.g., triangle) intersection checking on a serial computational model such as CPUs. We implemented the entire pipeline of our algorithm using off-the-shelf graphics processors (GPUs), such as nVIDIA GeForce 7800 GTX, for streaming computations, and Intel Dual Core 3.4G processors for serial computations. We benchmarked our algorithm with different models of varying complexities, ranging from 15K up to 50K triangles, under various deformation motions, and the timings were obtained as 30~100 FPS depending on the complexity of models and their relative configurations. Finally, we made comparisons with a well-known GPU-based collision detection algorithm, CULLIDE [4] and observed about three times performance improvement over the earlier approach. We also made comparisons with a SW-based AABB culling algorithm [2] and observed about two times improvement.

• Journal of Information Processing Systems
• /
• v.8 no.1
• /
• pp.55-66
• /
• 2012

This paper presents a dual modeling method that simulates the graphic and haptic behavior of a volumetric deformable object and conveys the behavior to a human operator. Although conventional modeling methods (a mass-spring model and a finite element method) are suitable for the real-time computation of an object's deformation, it is not easy to compute the haptic behavior of a volumetric deformable object with the conventional modeling method in real-time (within a 1kHz) due to a computational burden. Previously, we proposed a fast volume haptic rendering method based on the S-chain model that can compute the deformation of a volumetric non-rigid object and its haptic feedback in real-time. When the S-chain model represents the object, the haptic feeling is realistic, whereas the graphical results of the deformed shape look linear. In order to improve the graphic and haptic behavior at the same time, we propose a dual modeling framework in which a volumetric haptic model and a surface graphical model coexist. In order to inspect the graphic and haptic behavior of objects represented by the proposed dual model, experiments are conducted with volumetric objects consisting of about 20,000 nodes at a haptic update rate of 1000Hz and a graphic update rate of 30Hz. We also conduct human factor studies to show that the haptic and graphic behavior from our model is realistic. Our experiments verify that our model provides a realistic haptic and graphic feeling to users in real-time.