Glyphs for visualizing uncertainty in vector fields

Abstract

Environmental data have inherent uncertainty which is often ignored in visualization. Meteorological stations and doppler radars, including their time series averages, have a w ealth of uncertainty information that traditional vector visualization methods such as meteorological wind barbs and arrow glyphs simply ignore. We h a ve d e v eloped a new vector glyph to visualize uncertainty in winds and ocean currents. Our approach is to include uncertainty in direction and magnitude, as well as the mean direction and length, in vector glyph plots. Our glyph shows the variation in uncertainty, and provides fair comparisons of data from instruments, models, and time averages of varying certainty. W e also de ne visualizations that incorporate uncertainty in an unambiguous manner as verity visualization. We use both quantitative and qualitative methods to compare our glyphs to traditional ones. Subjective comparison tests with experts are provided, as well as objective tests, where the information density of our new glyphs and traditional glyphs are compared. The design of the glyph and numerous examples using environmental data are given. We s h o w enhanced visualizations, data together with their uncertainty information, that may improve understanding of environmental vector eld data quality.

How to Assess Visual Communication of Uncertainty? A Systematic Review of Geospatial Uncertainty Visualisation User Studies

“…Studies that do not appear in our list include, e.g. conceptual evaluations that use heuristics derived from general guidelines and rules for data visualisation coined by Bertin, Tufte, Ware and Chambers (Riveiro, 2007a;Riveiro, 2007b;Wittenbrink et al, 1996;Zuk and Carpendale, 2006). Such studies, while not our focus here, do provide basic statements on the usability of different methods and therefore can help to choose suitable visualisation techniques.…”

“…Pang and colleagues designed glyphs to represent data and uncertainty in combination. In an early study by Wittenbrink et al (1996), the authors compared arrow glyphs including uncertainty information ('verity visualisation') to common arrow glyphs without uncertainty and found that they encoded bearing, magnitude, and uncertainty with almost the same effectiveness as with the simple arrow glyphs. In the study by Newman and Lee (2004) already mentioned above, three extrinsic techniques received the highest ratings regarding effectiveness: multi-point, ball and arrow glyphs.…”

“…We identified two kinds of value retrieval tasks that are used. In the first, data and/or uncertainty values have to be retrieved separately (Aerts et al, 2003;Alberti, 2013;Kubíček and Šašinka, 2011;MacEachren et al, 1998;Nadav-Greenberg et al, 2008;Wittenbrink et al, 1996). In the second, retrieval of both data values and uncertainty happens simultaneously (Blenkinsop et al, 2000;Drecki, 2002;Kolbeinsson, 2013;Kubíček and Šašinka, 2011).…”

“…Much of the work has focused on developing typologies of uncertainty that represent various aspects of data and how it might be signified (Buttenfield and Weibel, 1988;Pang et al, 1997;Sanyal et al, 2009;Thomson et al, 2005) and on developing methods to depict uncertainty visually (e.g. Cedilnik and Rheingans, 2000;Ehlschlaeger et al, 1997;Sanyal et al, 2010;Wittenbrink et al, 1996). A comprehensive review of uncertainty typologies is provided by MacEachren et al (2005) and a review of uncertainty visualisation across science by Brodlie et al (2012).…”

Volume Rendering Data with Uncertainty Information

“…For example, Cedilnik and Rheingans [1] looked at different ways of imparting uncertainty over 2D fields using procedural methods to distort overlaid grid lines, Interrante [3] discussed how one might use natural textures over a map to show uncertainty, Djurcilov and Pang [2] looked at different ways of incorporating uncertainty information in contour lines and isosurfaces of sparse data sets, Wittenbrink et al [11] included uncertainty in direction and uncertainty in magnitude into glyph designs, and Pang et al [7] described some general methods for incorporating uncertainty into visual displays.…”