Taosong He

Wavelet-based volume morphing

This paper presents a technique for performing volume morphing between two volumetric datasets in the wavelet domain. The idea is to decompose the volumetric datasets into a set of frequency bands, apply smooth interpolation to each band, and reconstruct to form the morphed model. In addition, a technique for establishing a suitable correspondence among object voxels is presented. The combination of these two techniques results in a smooth transition between the two datasets and produces morphed volume with fewer high frequency distortions than those obtained from spatial domain volume morphing.<<ETX>>

Voxel based object simplification

Presents a simple, robust and practical method for object simplification for applications where gradual elimination of high-frequency details is desired. This is accomplished by sampling and low-pass filtering the object into multi-resolution volume buffers and applying the marching cubes algorithm to generate a multi-resolution triangle-mesh hierarchy. Our method simplifies the genus of objects and can also help existing object simplification algorithms achieve better results. At each level of detail, a multi-layered mesh can be used for an optional and efficient antialiased rendering.

Controlled topology simplification

We present a simple, robust, and practical method for object simplification for applications where gradual elimination of high frequency details is desired. This is accomplished by converting an object into multi resolution volume rasters using a controlled filtering and sampling technique. A multiresolution triangle mesh hierarchy can then be generated by applying the Marching Cubes algorithm. We further propose an adaptive surface generation algorithm to reduce the number of triangles generated by the standard Marching Cubes. Our method simplifies the topology of objects in a controlled fashion. In addition, at each level of detail, multilayered meshes can be used for an efficient antialiased rendering.

VolVis: a diversified volume visualization system

VolVis is a diversified, easy to use, extensible, high performance, and portable volume visualization system for scientists and engineers as well as for visualization developers and researchers. VolVis accepts as input 3D scalar volumetric data as well as 3D volume-sampled and classical geometric models. Interaction with the data is controlled by a variety of 3D input devices in an input device-independent environment. VolVis output includes navigation preview, static images, and animation sequences. A variety of volume rendering algorithms are supported ranging from fast rough approximations, to compression-domain rendering, to accurate volumetric ray tracing and radiosity, and irregular grid rendering.<<ETX>>

Integrated volume compression and visualization

Volumetric data sets require enormous storage capacity even at moderate resolution levels. The excessive storage demands not only stress the capacity of the underlying storage and communications systems, but also seriously limit the speed of volume rendering due to data movement and manipulation. A novel volumetric data visualization scheme is proposed and implemented in this work that renders 2D images directly from compressed 3D data sets. The novelty of this algorithm is that rendering is performed on the compressed representation of the volumetric data without pre-decompression. As a result, the overheads associated with both data movement and rendering processing are significantly reduced. The proposed algorithm generalizes previously proposed whole-volume frequency-domain rendering schemes by first dividing the 3D data set into subcubes, transforming each subcube to a frequency-domain representation, and applying the Fourier projection theorem to produce the projected 2D images according to given viewing angles. Compared to the whole-volume approach, the subcube-based scheme not only achieves higher compression efficiency by exploiting local coherency, but also improves the quality of resultant rendering images because it approximates the occlusion effect on a subcube by subcube basis.

Fast stereo volume rendering

We present new volume rendering techniques for efficiently generating high-quality stereoscopic images and propose criteria to evaluate stereo volume rendering algorithms. Specifically, we present fast stereo volume ray casting algorithms using segment composition and linearly-interpolated re-projection. A fast stereo shear-warp volume rendering algorithm is also presented and discussed.

Navigation and Animation in a Volume Visualization System

The VolVis system for volume visualization supports numerous visualization algorithms and methods within a consistent and well-organized framework. Navigation and Animation components have been incorporated into VolVis which allow interactive object manipulation and quick specification of complex animation sequences. Navigation is controlled by a variety of 2D and 3D input devices. VolVis includes a unified protocol for communicating with these input devices, allowing for input device independent development.