Byoung-Tae Choi

Layered-depth image using pixel grouping

Recent advance in computer hardware and Internet technology makes more realistic images affordable on our computer systems. However, the image creation by using conventional geometry modelling have limitations in terms of rendering time and image quality to be used in interactive rendering applications. Image-based rendering (IBR) technique is a good solution to reducing those limitations in such applications. As an improvement on the well-known layered-depth image (LDI) method, we propose a way of pixel grouping from depth images and making image generation efficient by utilizing the information obtained from the grouping.

Hierarchical triangular patches for terrain rendering with their matching blocks

To efficiently represent large artificial terrains on todays graphic hardwares, we propose a new terrain rendering scheme with hierarchical triangular patches and pre-constructed match ing blocks. It renders terrain patches at different LODs(levels-of-details) according to the current visual requirement. The hierarchical structure can reduce the total number of draw primitive(DirectX) calls significantly by replacing a large set of triangles with a single patch where appropriate while other conventional methods try to reduce the total number of primitives to be rendered. After the initial construction of patches, the new scheme does not re-triangulate during runtime, further enhancing its performance. We also propose a specially designed matching method to eliminate cracks on the boundaries between neighboring patches. It constructs a few matching blocks at initialization with which it replaces original patches on boundaries where cracks may occur.

Camera motion estimation in ocean scene

CG and Photo-realistic image composition in ocean scenes is frequently used in movies and TV advertisement. For complete image composition, we need camera motion data. In the case of an ocean scene, camera tracking is a very difficult task because its impossible to use calibration tool in outdoor environment. Auto-calibration algorithm proposed by Pollefeys is also not appropriate because natural features like KLT cant be extracted from ocean background. We propose a simple, practical method for solving camera motion tracking using previous knowledge about background structure. We applied our method to the production of a commercial movie, Hanbando and the result was satisfactory.

High dynamic range image texture mapping based on VRML

In this paper, we describe a technique for representing and displaying high dynamic range image (HDRI) as a texture map in VRML structure. To do this, we designed and implemented extended texture nodes for supporting HDRI in VRML and developed HDRI-based mapping tool that can be used for authoring objects with HDR image as a texture data. Even though the authoring result of our tool is not identical with standard VRML format exactly, it is good enough to be used in virtual world. To verify this, we developed an extended VRML browser that supports a parsing and viewing of our new texture nodes related to HDRI and allows the exposure to be adjusted continuously and arbitrarily at the time of navigation.