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Map visualization


Perhaps the most important features of ENTIRE are its visualization capabilities. The visualization is based on two different kinds of presentations of the map: the component planes and the u-matrix, shown in figure 4.2. Both are visualized as 2-dimensional colour images, where the colour of a map unit corresponds to its value. On top of these images different kinds of markings can be drawn including labels and operation point trajectories. The ability to show several component planes at the same time is an important property, because it allows direct visual inspection of correlations between components. In addition to component planes and u-matrix, the user can calculate and visualize the Sammon's projection of the SOM (see figure 4.4).

The basic colour map used by ENTIRE is a gray scale of 100 shades ranging from pure white to pure black. The colour map can be changed, however. Using the colour controls shown in figure 4.3a the user can select the number of colours used, the range of values they correspond to and the specific colours themselves. Figure 4.3b shows four different kinds of views of a component plane. In the first image (top left) the standard set of 100 shades of gray are used. In the second image (top right) only 5 colours are used. Also in the third image (bottom left) 5 colours are used, but their positioning is logarithmic rather than equidistant. In the last image (bottom right) only two colours are used and the bottom colour has been changed to red. Using a smaller number of colours is sometimes beneficial because it visualizes better the categories of values that can be found from the map.

Juha Vesanto
Tue May 27 12:40:37 EET DST 1997