Francesca Samsel

Colormaps that Improve Perception of High-Resolution Ocean Data

Scientists from the Climate, Ocean and Sea Ice Modeling Team (COSIM) at the Los Alamos National Laboratory (LANL) are interested in gaining a deeper understanding of three primary ocean currents: the Gulf Stream, the Kuroshio Current, and the Agulhas Current & Retroflection. To address these needs, visual artist Francesca Samsel teamed up with experts from the areas of computer science, climate science, statistics, and perceptual science. By engaging an artist specializing in color, we created colormaps that provide the ability to see greater detail in these high-resolution datasets. The new colormaps applied to the POP dataset enabled scientists to see areas of interest unclear using standard colormaps. Improvements in the perceptual range of color allowed scientists to highlight structures within specific ocean currents. Work with the COSIM team members drove development of nested colormaps which provide further detail to the scientists.

The Good, the Bad, and the Ugly: A Theoretical Framework for the Assessment of Continuous Colormaps

A myriad of design rules for what constitutes a “good” colormap can be found in the literature. Some common rules include order, uniformity, and high discriminative power. However, the meaning of many of these terms is often ambiguous or open to interpretation. At times, different authors may use the same term to describe different concepts or the same rule is described by varying nomenclature. These ambiguities stand in the way of collaborative work, the design of experiments to assess the characteristics of colormaps, and automated colormap generation. In this paper, we review current and historical guidelines for colormap design. We propose a specified taxonomy and provide unambiguous mathematical definitions for the most common design rules.

Interactive Colormapping: Enabling Multiple Data Range and Detailed Views of Ocean Salinity

Ocean salinity is a critical component to understanding climate change. Salinity concentrations and temperature drive large ocean currents which in turn drive global weather patterns. Melting ice caps lower salinity at the poles while river deltas bring fresh water into the ocean worldwide. These processes slow ocean currents, changing weather patterns and producing extreme climate events which disproportionally affect those living in poverty. Analysis of salinity presents a unique visualization challenge. Important data are found in narrow data ranges, varying with global location. Changing values of salinity are important in understanding ocean currents, but are difficult to map to colors using traditional tools. Commonly used colormaps may not provide sufficient detail for this data. Current editing tools do not easily enable a scientist to explore the subtleties of salinity. We present a workflow, enabled by an interactive colormap tool that allows a scientist to interactively apply sophisticated colormaps to scalar data. The intuitive and immediate interaction of the scientist with the data is a critical contribution of this work.

Visualization and Analysis of Large-Scale Atomistic Simulations of Plasma-Surface Interactions

We present a simulation–visualization pipeline that uses the LAMMPS Molecular Dynamics Simulator and the Visualization Toolkit to create a visualization and analysis environment for atomistic simulations of plasma–surface interactions. These simulations are used to understand the origin of fuzz-like, microscopic damage to tungsten and other metal surfaces by helium. The proposed pipeline serves both as an aid to visualization, i.e. drawing the surfaces of gas bubbles and voids/cavities in the metal, as well as a means of analysis, i.e. extracting various statistics and gas bubble evolution details. The result is a better understanding of the void and bubble formation process that is difficult if not impossible to get using conventional atomistic visualization software.

Employing Color Theory to Visualize Volume-rendered Multivariate Ensembles of Asteroid Impact Simulations

We describe explorations and innovations developed to help scientists understand an ensemble of large scale sim- ulations of asteroid impacts in the ocean. The simulations were run to help scientists determine the characteristics of asteroids that NASA should track, so that communities at risk from impact can be given advanced notice. Of rel- evance to the CHI community are 1) hands-on workflow issues specific to exploring ensembles of large scientific data, 2) innovations in exploring such data ensembles with color, and 3) examples of multidisciplinary collaboration.

Coming Into Focus: An Interview with Ellen Jantzen

Ellen Jantzen, the artist (www.ellenjantzen.com), works with geographic composition that focuses attention on graphic elements in a scene, which might make her career particularly interesting to those working with geographic data and visualization. Her work explores reality and time, both how it is experienced and revealed, and the healing powers of the natural environment.

Analyzing Task-Based User Study Data to Determine Colormap Efficiency

Domain scientists need colormaps to visualize their data and are especially useful for identifying areas of interest, like in ocean data to identify eddies or characterize currents. However, traditional Rainbow colormap performs poorly for understanding details, because of the small perceptual range. In order to assist domain scientists in recognizing and identifying important details in their data, different colormaps need to be applied to allow higher perceptual definition. Visual artist Francesca Samsel used her understanding of color theory to create new colormaps to improve perception. While domain scientists find the new colormaps to be useful, we implemented a rigorous and quantitative study to determine whether or not the new colormaps have perceptually more colors. Color count data from one of these studies will be analyzed in depth in order to determine whether or not the new colormaps have more perceivable colors and what affects the number of perceivable colors.

Murmurations: Drawing Together Art, Visualization, and Physical Phenomena

Dennis Hylnsky, a professor at the Rhode Island School of Design and head of the Film/Animation/Video Department, is a practicing artist and early adopter of electronic media. At RISD he has studied 3D modeling and animation. One of his current projects focuses on the movement of small animals and what animal visualizations can tell us. In this issues Art on Graphics, department editors Bruce Campbell and Francesca Samsel talk with Hylnsky about his work and how it can help to bridge the gap between art and science practice and facilitate a dialogue between the two communities.

Oil, pixels and poetry

Oil, Pixels and Poetry is a collaboration between TACC, their 75-monitor tile display and Francesca Samsel, a visual artist, producing a series depicting the 2010 Gulf Oil Disaster.