This paper proposes to pre-compute approximate normal distribution functions and store them in textures such that real-time applications can process complex specular surfaces simply by sampling the textures. The proposed method is compatible with the GPU pipeline-based algorithms, and rendering is completed at real time. The experimental results show that the features of complex specular surfaces, such as the glinty appearance of leather and metallic flakes, are successfully reproduced.

Shadow is an important effect that makes virtual 3D scenes more realistic. In this paper, we propose a fast and correct soft shadow generation method for area lights of various shapes and colors. To conduct efficient as well as accurate visibility tests, we exploit the complexity of shadow and area light color.

Recently in the mobile graphic industry, ultra-realistic visual qualities with 60fps and limited power budget for GPU have been required. For graphics-heavy applications that run at 30 fps, we easily observed very noticeable flickering artifacts. Further, the workload imposed by high resolutions at high frame rates directly decreases the battery life. Unlike the recent frame rate up sampling algorithms which remedy the flickering but cause inevitable significant overheads to reconstruct intermediate frames, we propose a dynamic rendering quality scaling (DRQS) that includes dynamic rendering based on resolution changes and quality scaling to increase the frame rate with negligible overhead using a transform matrix. Further DRQS reduces the workload up to 32% without human visual-perceptual changes for graphics-light applications.

Light source estimation and virtual lighting must be believable in terms of appearance and correctness in augmented reality scenes. As a result of illumination complexity in an outdoor scene, realistic lighting for augmented reality is still a challenging problem. In this paper, we propose a framework based on an estimation of environmental lighting from well-defined objects, specifically human faces. The method is tuned for outdoor use, and the algorithm is further enhanced to illuminate virtual objects exposed to direct sunlight. Our model can be integrated into existing mobile augmented reality frameworks to enhance visual perception.

Massive digital elevation models require a large number of geometric primitives that exceed the throughput of the existing graphics hardware. For the interactive visualization of these datasets, several adaptive reconstruction methods that reduce the number of primitives have been introduced over the decades. Quadtree triangulation, based on subdivision of the terrain into rectangular patches at different resolutions, is the most frequently used terrain reconstruction method. This usually accomplishes the triangulation using LOD (level-of-detail) selection and crack removal based on geometric errors. In this paper, we present bimodal vertex splitting, which performs LOD selection and crack removal concurrently on a GPU. The first mode splits each vertex for LOD selection and the second splits each vertex for crack removal. By performing these two operations concurrently on a GPU, we can efficiently accelerate the rendering speed by reducing the computation time and amount of transmission data in comparison with existing quadtree-based rendering methods.

In terrain visualization, the quadtree is the most frequently used data structure for progressive mesh generation. The quadtree provides an efficient level of detail selection and view frustum culling. However, most applications using quadtrees are performed on the CPU, because the pointer and recursive operation in hierarchical data structure cannot be manipulated in a programmable rendering pipeline. We present a quadtree-based terrain rendering method for GPU (Graphics Processing Unit) execution that uses vertex splitting and triangle splitting. Vertex splitting supports a level of detail selection, and triangle splitting is used for crack removal. This method offers higher performance than previous CPU-based quadtree methods, without loss of image quality. We can then use the CPU for other computations while rendering the terrain using only the GPU.

Caustics are patterns of light focused by reflective or refractive objects. Because of their visually fascinating patterns, several methods have been developed to render caustics. We propose a method for the quick rendering of caustics formed by refracted and converged light through transparent objects. First, in the preprocess, we calculate sampling rays incident on each vertex of the object, and trace the rays until they leave the object taking refraction into account. The position and direction of each ray that finally transmits the transparent object are obtained and stored in a lookup table. Next, in the rendering process, when the object is illuminated, the positions and directions of the rays leaving the object are calculated using the lookup table. This makes it possible to render refractive caustics due to transparent objects at interactive frame rates, allowing us to change the light position and direction, and translate and rotate the object.

We present a new method in multiresolution rendering of a complex object. Our method uses viewer-centered features including the silhouette in generating multiresolution model. Because the silhouette of an object depends on the position of the viewer, the silhouette has difficulties in real-time generation. We propose the AGSphere for real-time management of the silhouette. The AGSphere easily identifies silhouette parts and manages it in multiresolution manner. The primary applicable feature of the AGSphere is the silhouette from the viewer, but we can also use the AGSphere for other directional features like light silhouette. In this paper, we show experimental results for the silhouette either from the viewer or the light. The efficiency of the proposed method is compared with other methods. We also propose new texture map generation method to use with the multiresolution geometry. Generated texture map has valid mapping function for the multiresolution geometry minimizing texture distortions.