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| = Pargnostics: Screen-Space Metrics for Parallel Coordinates =
| | You've hit the ball out the park! Icnrdeible! |
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| == Introduction ==
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| Visualization still takes place in a space with a limited number of discrete
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| pixels. The result of this often is over-plotting, clutter or other things.
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| Most of the time this structures are avoided. But sometimes this artifacts can be useful, because they might point out interesting structures in the data.
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| Until know not a lot of attention is paid to the way visualzation is presented on the screen.
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| For the case of parallel coordinates so called Pargnostics (Parallel coordinates diagnostics) should act as a bridge between the created visualization and the perceptual system of the user.
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| Based on metrics it's possible to provide an optimization which maximize or minimize certain visual artifacts.
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| == Metrics ==
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| [[Image:Dasgupta+Kosara Pixel-Space Histograms.png|thumb|300px|right|Figure 1: Pixel-space histograms, see [Dasgupta and Kosara, 2010] p1018]]
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| To automatically enhance the analytical tasks of users Dasgupta and Kosara [2010] proposed several metrics.
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| The metrics are used to measure the properties of parallel coordinates.
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| For calculating these metrics, first ''pixel-space histograms'' need to be calculated.
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| Pixel-space histograms discretize the lines drawn in parallel coordinates into bins - each bin being one pixel (for a total of ''h'' pixels in an axis):
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| * ''One-Dimensional Axis Histogram'': A vector ''b'' containing the number of lines that start or end at this pixel - see columns A and B in figure 1.
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| * ''One-Dimensional Distance Histogram'': A vector ''d'' where each component measures the slope of lines.
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| * ''Two-Dimensional Axis Pair Histogram'': A matrix where each cell ''x<sub>i,j</sub>'' means that ''n'' lines are going from pixel ''i'' to pixel ''j'' - see matrix in figure 1.
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| === Metrics ... ===
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| * Number of Line Crossings
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| * Angles of Crossing
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| * Parallelism
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| * Mutual Information
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| * Convergence, Divergence
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| * Over-plotting
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| * Pixel-based Entropy
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| == Dimension Order Optimization ==
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| == Conclusion ==
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| == References ==
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| [Dasgupta and Kosara, 2010] Aritra Dasgupta and Robert Kosara. Pargnostics: Screen-Space Metrics for Parallel Coordinates. ''IEEE Transactions on Visualization and Computer Graphics'', 16(6):1017-1026, November/December 2010
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