The Volume plot attributes window provides controls for setting the limits of the variable being plotted. Limits are artificial minima or maxima that are specified by the user. Setting the limits to a smaller range of values than present in the database cause the plot's colors to be distributed among a smaller range of values, resulting in a plot with more color variety.
You set the limits for the variable being plotted in the Color area of the window. To set the limits are set by first clicking the Min or Max check box next to the Min or Max text field. Clicking a check box enables a text field into which you can type a new minimum or maximum value.
Like VisIt's other plots that map scalar values to colors, the Volume plot allows for the data values to be scaled using Linear, Log, and Skew functions. To select a scaling function other than linear where values in the data range are mapped 1:1 to values in the color range, click on the Log10 or Skew radio buttons.