What May Visualization Processes Optimize?

In this paper, we present an abstract model of visualization and inference processes and describe an information-theoretic measure for optimizing such processes. In order to obtain such an abstraction, we first examined six classes of workflows in data analysis and visualization, and identified four levels of typical visualization components, namely disseminative, observational, analytical and model-developmental visualization. We noticed a common phenomenon at different levels of visualization, that is, the transformation of data spaces (referred to as alphabets) usually corresponds to the reduction of maximal entropy along a workflow. Based on this observation, we establish an information-theoretic measure of cost-benefit ratio that may be used as a cost function for optimizing a data visualization process. To demonstrate the validity of this measure, we examined a number of successful visualization processes in the literature, and showed that the information-theoretic measure can mathematically explain the advantages of such processes over possible alternatives.Comment: 10 page

Three-dimensional Radial Visualization of High-dimensional Datasets with Mixed Features

We develop methodology for 3D radial visualization (RadViz) of high-dimensional datasets. Our display engine is called RadViz3D and extends the classical 2D RadViz that visualizes multivariate data in the 2D plane by mapping every record to a point inside the unit circle. We show that distributing anchor points at least approximately uniformly on the 3D unit sphere provides a better visualization with minimal artificial visual correlation for data with uncorrelated variables. Our RadViz3D methodology therefore places equi-spaced anchor points, one for every feature, exactly for the five Platonic solids, and approximately via a Fibonacci grid for the other cases. Our Max-Ratio Projection (MRP) method then utilizes the group information in high dimensions to provide distinctive lower-dimensional projections that are then displayed using Radviz3D. Our methodology is extended to datasets with discrete and continuous features where a Gaussianized distributional transform is used in conjunction with copula models before applying MRP and visualizing the result using RadViz3D. A R package radviz3d implementing our complete methodology is available.Comment: 12 pages, 10 figures, 1 tabl

Mode transition of plasma expansion for laser induced breakdown in Air

High-speed shadowgraph visualization experiments conducted using a 10 J pulse transversely excited atmospheric (TEA) CO2 laser in ambient air provided a state transition from overdriven to Chapman–Jouguet in the laser-supported detonation regime. At the state transition, the propagation velocity of the laser-supported detonation wave and the threshold laser intensity were 10 km/s and 1011 W/m2, respectively. State transition information, such as the photoionization caused by plasma UV radiation, of the avalanche ionization ahead of the ionization wave front can be elucidated from examination of the source seed electrons

Simulation of fluid flows during growth of organic crystals in microgravity

Several counter diffusion type crystal growth experiments were conducted in space. Improvements in crystal size and quality are attributed to reduced natural convection in the microgravity environment. One series of experiments called DMOS (Diffusive Mixing of Organic Solutions) was designed and conducted by researchers at the 3M Corporation and flown by NASA on the space shuttle. Since only limited information about the mixing process is available from the space experiments, a series of ground based experiments was conducted to further investigate the fluid dynamics within the DMOS crystal growth cell. Solutions with density differences in the range of 10 to the -7 to 10 to the -4 power g/cc were used to simulate microgravity conditions. The small density differences were obtained by mixing D2O and H2O. Methylene blue dye was used to enhance flow visualization. The extent of mixing was measured photometrically using the 662 nm absorbance peak of the dye. Results indicate that extensive mixing by natural convection can occur even under microgravity conditions. This is qualitatively consistent with results of a simple scaling analysis. Quantitave results are in close agreement with ongoing computational modeling analysis

Top 10 unsolved information visualization problems

IEEE Computer Graphics and Applications, 25 (4). 12-16. Retrieved 6/21/2006 from http://www.pages.drexel.edu/~cc345/papers/cga2005.pdf.Athought-provoking panel, organized by Theresa- Marie Rhyne, at IEEE Visualization 2004 addressed the top unsolved problems of visualization.1 Two of the invited panelists, Bill Hibbard and Chris Johnson, addressed scientific visualization problems. Steve Eick and I identified information visualization problems. The following top 10 unsolved problems list is a revised and extended version of the information visualization problems I outlined on the panel. These problems are not necessarily imposed by technical barriers; rather, they are problems that might hinder the growth of information visualization as a field. The first three problems highlight issues from a user-centered perspective. The fifth, sixth, and seventh problems are technical challenges in nature. The last three are the ones that need tackling at the disciplinary level

Environmental Flow Regimes for Dysidea avara Sponges

The aim of our research is to design tank systems to culture Dysidea avara for the production of avarol. Flow information was needed to design culture tanks suitable for effective production. Water flow regimes were characterized over a 1-year period for a shallow rocky sublittoral environment in the Northwestern Mediterranean where D. avara sponges are particularly abundant. Three-dimensional Doppler current velocities at 8¿10-m depths ranged from 5 to 15 cm/s over most seasons, occasionally spiking to 30¿66 cm/s. A thermistor flow sensor was used to map flow fields in close proximity (¿2 cm) to individual sponges at 4.5-, 8.8-, and 14.3-m depths. These ¿proximal flows¿ averaged 1.6 cm/s in calm seas and 5.9 cm/s during a storm, when the highest proximal flow (32.9 cm/s) was recorded next to a sponge at the shallowest station. Proximal flows diminished exponentially with depth, averaging 2.6 cm/s¿±¿0.15 SE over the entire study. Flow visualization studies showed that oscillatory flow (0.20¿0.33 Hz) was the most common regime around individual sponges. Sponges at the 4.5-m site maintained a compact morphology with large oscula year-around despite only seasonally high flows. Sponges at 8.8 m were more erect with large oscula on tall protuberances. At the lowest-flow 14.3-m site, sponges were more branched and heavily conulated, with small oscula. The relationship between sponge morphology and ambient flow regime is discussed