Change the Method for Determining the Center Color Value

In the Options dialog box for a visualization, you can change the method that Vision uses to determine the center value for the color gradient. (You can also change the center value manually in the Visualization window.)

Vision uses your selection in Color Shading on the Metrics tab of the Options dialog box to determine the metric value that marks the central point in the range of colors for a metric. By default, blocks with a metric value equal to that center value are white. Blocks with higher values are displayed in lighter or darker shades of the high color, and blocks with lower values are displayed in lighter or darker shades of the low color.

To change the method that Vision uses to determine the center value for the color gradient, complete the following steps:

1. In the Reports grid, click the Options column for the visualization.
2. Click to display the Options dialog box.
3. Click the Metrics tab.
4. In the row for the metric for which you want to change the method, select one of the following settings in Color Shading:

   Option	Description
   Average	Vision determines the center value based on an average of the values for the metric: Sum of the metric values / Number of values.
   Manual	You enter, in the associated High Color Value and Low Color Value fields, specific metric values at which Vision displays the pure high and low colors. Vision then sets the metric value that marks the central point in the range of colors at the average of these two values. (You might want to select Manual if you first selected Average, and colors in the visualization map were so similar that it was difficult to distinguish the differences in metric value. If you narrow the range of the color gradient, color differences between blocks are more pronounced.)
   Zero Center	Zero is the center value. Vision displays blocks in the pure center color (white, by default) if the metric equals zero. Blocks with negative metric values are varying combinations of the center color and low color, and blocks with positive values are varying combinations of the center color and high color. This option is often the best choice for a metric that commonly has both positive and negative values.

5. Repeat step 4 for each metric for which you want to change the color shading.
6. Click Apply.
7. Generate the visualization map.