Barry G. Becker

Sorting and hardware assisted rendering for volume visualization

We present some techniques for volume rendering unstructured data. Interpolation between vertex colors and opacities is performed using hardware assisted texture mapping, and color is integrated for use with a volume rendering system. We also present an O(n{sup 2}) method for sorting n arbitrarily shaped convex polyhedra prior to visualization. It generalizes the Newell, Newell and Sancha sort for polygons to 3-D volume elements.

Flow volumes for interactive vector field visualization

Flow volumes are the volumetric equivalent of stream lines. They provide more information about the vector field being visualized than do stream lines or ribbons. Presented is an efficient method for producing flow volumes, composed of transparently rendered tetrahedra, for use in an interactive system. The problems of rendering, subdivision, sorting, composing artifacts, and user interaction are dealt with. Efficiency comes from rendering only the volume of the smoke, and using hardware texturing and compositing.<<ETX>>

Unsteady flow volumes

Flow volumes are extended for use in unsteady (time-dependent) flows. The resulting unsteady flow volumes are the 3D analogs of streaklines. There are few examples where methods other than particle tracing have been used to visualize time-varying flows. Since particle paths can become convoluted in time, there are additional considerations to be made when extending any visualization technique to unsteady flows. We present some solutions to the problems which occur in subdivision, rendering and system design. We apply the unsteady flow volumes to a variety of field types, including moving multi-zoned curvilinear grids.

Vector field visualization

We present two new techniques for rendering 3D vector fields in scientific visualisation. We also present a new technique called texture splats for rendering these volumes efficiently.<<ETX>>

Bump shading for volume textures

Bump mapping was introduced as a method of rendering realistic shading on bumpy surfaces, without actually rendering a full 3D model of the bumps. Bump mapping works well for parameterized surfaces. The authors interpret the 3D texture as a displacement function to be added to the surface position.<<ETX>>

Using MineSet for knowledge discovery

MineSet aids knowledge discovery and supports decision making based on relational data. It uses visualization and data mining to arrive at interesting results. Providing diverse visualization tools lets users choose the most appropriate method for a given problem. The client-server architecture performs most of the computationally intensive tasks on a server, while the processed results return to the client for visualization. The paper discusses MineSet database visualization and data mining visualization.

Volume rendering of 3D scalar and vector fields at LLNL

Simulation of complex 3D phenomena generate data sets which are hard to comprehend using conventional 2D oriented visualization tools. One way to overcome this limitation is to use various volume visualization techniques. While early volume visualization techniques worked well on simple scalar volumes they failed to exploit frame buffer hardware capabilities and handle higher order data such as vector fields. Work at Lawrence Livermore National Laboratory has centered on developing new techniques and extending existing techniques. This paper describes the various algorithms developed for volume rendering, and presents new methods of examining vector fields in a volumetric fashion.

Approximating scatterplots of large datasets using distribution splats

Many situations exist where the plotting of large data sets with categorical attributes is desired in a 3D coordinate system. For example, a marketing company may conduct a survey involving one million subjects and then plot peoples favorite car type against their weight, height and annual income. Scatter point plotting, in which each point is individually plotted at its correspond cartesian location using a defined primitive, is usually used to render a plot of this type. If the dependent variable is continuous, we can discretize the 3D space into bins or voxels and retain the average value of all records falling within each voxel. Previous work employed volume rendering techniques, in particular, splatting, to represent this aggregated data, by mapping each average value to a representative color.