• Journal of the Korea Computer Graphics Society
• /
• v.7 no.1
• /
• pp.27-35
• /
• 2001

Shadows are important elements in producing a realistic image. In rendering. generation of the exact shape and position of shadow is crucial in providing the user with visual cues on the scene. While the shadow map technique quickly generates a shadow for the scene wherein objects and light sources are fixed. it gets slow down as they start to move. In this paper. we apply an image-based rendering technique to generate shadows in real-time using graphics hardware. Due to the heavy requirement of storage for a shadow map repository. we use a wavelet-based compression scheme for effective compression. Our method will be efficiently used in generating realistic scenes in many real-time applications such as 3D games and virtual reality systems.

• Journal of the Korea Computer Graphics Society
• /
• v.19 no.1
• /
• pp.11-20
• /
• 2013

This paper introduces a user interface for large 3D meshes in mobile systems, which have limited memory, screen size and battery power. A large 3D mesh is divided into partitions and simplified in multi-resolutions so a large file is transformed into a number of small data files and saved in a PC server. Only selected small files specified by the user are hierarchically transmitted to the mobile system for 3D browsing and rendering. A 3D preview in a pop-up shows a simplified mesh in the lowest resolution. The next step displays simplified meshes whose resolutions are automatically controlled by the user interactions. The last step is to render a set of detailed original partitions in a selected range. As a result, while minimizing using mobile system resources, our interface enables us to browse and display 3D meshes in mobile systems through real-time interactions. A mobile 3D viewer and a 3D app are also presented to show the utility of the proposed user interface.

• Journal of the Korea Computer Graphics Society
• /
• v.13 no.4
• /
• pp.1-6
• /
• 2007

In this paper we describe the method of controlling the animation of 3D characters according to ISO/IEC 19774 (H-Anim) specification, which has been released by Wed3D Consortium and ISO/IEC SC24 WG6. The animation structure of the H-Anim character can be defined and modified in our H-Anim editor program. Our H-Anim animator generates the character's motion automatically according to the input of motion parameters at the character's joints interactively. This paper is focused on the development of a motion generation tool for human-like characters defined by H-Anim structures.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• v.13 no.3
• /
• pp.1418-1433
• /
• 2019

In computer graphics, 3D mesh segmentation is a challenging research field. This paper presents a 3D mesh model segmentation algorithm that focuses on removing exterior salient parts from the original 3D mesh model based on prominent feature points and marching plane. To begin with, the proposed approach uses multi-dimensional scaling to extract prominent feature points that reside on the tips of each exterior salient part of a given mesh. Subsequently, a set of planes intersect the 3D mesh; one is the marching plane, which start marching from prominent feature points. Through the marching process, local cross sections between marching plane and 3D mesh are extracted, subsequently, its corresponding area are calculated to represent local volumes of the 3D mesh model. As the boundary region of an exterior salient part generally lies on the location at which the local volume suddenly changes greatly, we can simply cut this location with the marching plane to separate this part from the mesh. We evaluated our algorithm on the Princeton Segmentation Benchmark, and the evaluation results show that our algorithm works well for some categories.

• ETRI Journal
• /
• v.41 no.3
• /
• pp.277-288
• /
• 2019

VWorld is run by the Ministry of Land, Infrastructure, and Transport of South Korea and provides national spatial information, such as aerial images, digital elevation models, and 3D structural models. We propose herein an open platform for 3D spatial information based on WebGL using spatial information from VWorld. WebGL is a web-based graphics library and has the advantage of being compatible with various web browsers. Our open platform is also compatible with various web browsers. Accordingly, it is easily accessible via the VWorld site and uses the three-dimensional (3D) map program. In this study, we describe the proposed platform configuration, and the requests, management, and visualization approaches for VWorld spatial information data. Our aim is to establish an approach that will provide a stable rendering speed even on a low-end personal computer without a graphics processing unit based on a quadtree structure. We expect that users will be able to visualize 3D spatial information through the VWorld open platform, and that the proposed platform will become the basis for various applications.

• Journal of the Korea Computer Graphics Society
• /
• v.29 no.4
• /
• pp.17-24
• /
• 2023

In computer graphics and computer vision research and its applications, various representations of 3D objects, such as point clouds, voxels, or triangular meshes, are used depending on the purpose. The need for animating characters using these representations is also growing. In a typical animation pipeline called skeletal animation, "skinning weight painting" is required to determine how joints influence a vertex on the character's skin. In this paper, we introduce a neural network for automatically performing skinning weight painting for characters represented in various formats. We utilize signed distance fields (SDF) to handle different representations and employ graph neural networks and multi-layer perceptrons to predict the skinning weights for a given point.

• Journal of KIISE:Computer Systems and Theory
• /
• v.29 no.8
• /
• pp.431-439
• /
• 2002

Due to the recent development of graphics hardware, real-time rendering of complex scenes is still a challenging task. As results of researches on image based rendering, the rendering schemes based on post-rendering 3D warping have been proposed. In general, these methods produce good rendering results. However, they are not appropriate for real-time rendering since it is not easy to accelerate the time-consuming algorithms within graphics subsystem. As an attempt to resolve this problem of the post-rendering 3D warping technique, we present a new real-time scheme based on projective texture. In our method, two reference images obtained by rendering complicated objects at two consecutive points of time are used. Rendering images of high quality for intermediate points of time are obtained by projecting the reference images onto a simplified object, and then blending the resulting images. Our technique will be effectively used in developing real-time graphics applications such as 3D games and virtual reality software and so on.

• Journal of Computing Science and Engineering
• /
• v.4 no.3
• /
• pp.207-224
• /
• 2010

This paper presents a compression scheme for mesh geometry, which is suitable for mobile graphics. The main focus is to enable real-time decoding of compressed vertex positions while providing reasonable compression ratios. Our scheme is based on local quantization of vertex positions with mesh partitioning. To prevent visual seams along the partitioning boundaries, we constrain the locally quantized cells of all mesh partitions to have the same size and aligned local axes. We propose a mesh partitioning algorithm to minimize the size of locally quantized cells, which relates to the distortion of a restored mesh. Vertex coordinates are stored in main memory and transmitted to graphics hardware for rendering in the quantized form, saving memory space and system bus bandwidth. Decoding operation is combined with model geometry transformation, and the only overhead to restore vertex positions is one matrix multiplication for each mesh partition. In our experiments, a 32-bit floating point vertex coordinate is quantized into an 8-bit integer, which is the smallest data size supported in a mobile graphics library. With this setting, the distortions of the restored meshes are comparable to 11-bit global quantization of vertex coordinates. We also apply the proposed approach to compression of vertex attributes, such as vertex normals and texture coordinates, and show that gains similar to vertex geometry can be obtained through local quantization with mesh partitioning.

• Proceedings of the Korean Information Science Society Conference
• /
• 2006.06a
• /
• pp.196-198
• /
• 2006

Shader architecture is one of the fastest growing fields in the ever advancing 3D graphics, and massive amounts of Ideas and technologies are being introduced to the market continuously. In this paper, we present a flexible cycle-accurate simulation environment to accelerate and alleviate the process of developing and verifying these ideas and technologies. Combination of 3D graphics API and hardware simulator allows OpenGL applications to be emulated off-the-shelf for a given shader micro-architecture. Easily modified parameters allow the simulation environment to be tailored to specific demands or requirements.

• Journal of the Korea Computer Graphics Society
• /
• v.24 no.2
• /
• pp.29-40
• /
• 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.