The intensity graph works the same as the intensity chart, except it does not retain previous data values and does not include update modes. Each time new data values pass to an intensity graph, the new data values replace old data values. Like other graphs, the intensity graph can have cursors. Each cursor displays the x, y, and z values for a specified point on the graph.

Using Color Mapping with Intensity Graphs and Charts

An intensity graph or chart uses color to display 3D data on a 2D plot. When you set the color mapping for an intensity graph or chart, you configure the color scale of the graph or chart. The color scale consists of at least two arbitrary markers, each with a numeric value and a corresponding display color. The colors displayed on an intensity graph or chart correspond to the numeric values associated with the specified colors. Color mapping is useful for visually indicating data ranges, such as when plot data exceeds a threshold value.

You can set the color mapping interactively for the intensity graph and chart the same way you define the colors for a color ramp numeric control.

You can set the color mapping for the intensity graph and chart programmatically by using the Property Node in two ways. Typically, you specify the value-to-color mappings in the Property Node. For this method, specify the Z Scale:Marker Values property for the z-scale. This property consists of an array of clusters, in which each cluster contains a numeric limit value and the corresponding color to display for that value. When you specify the color mapping in this manner, you can specify an upper out-of-range color using the Z Scale:High Color property for the z-scale and a lower out-of-range color using the Z Scale:Low Color property for the z-scale. The intensity graph and chart are limited to a total of 254 colors, with the lower and upper out-of-range colors bringing the total to 256 colors. If you specify more than 254 colors, the intensity graph or chart creates the 254-color table by interpolating among the specified colors.

If you display a bitmap on the intensity graph, you specify a color table using the Color Table property. With this method, you can specify an array of up to 256 colors. Data passed to the chart are mapped to indexes in this color table based on the color scale of the intensity chart. If the color scale ranges from 0 to 100, a value of 0 in the data is mapped to index 1, and a value of 100 is mapped to index 254, with interior values interpolated between 1 and 254. Anything below 0 is mapped to the out-of-range below color (index 0), and anything above 100 is mapped to the out-of-range above color (index 255).

Note The colors you want the intensity graph or chart to display are limited to the exact colors and number of colors your video card can display. You also are limited by the number of colors allocated for your display.

Refer to the Modifying the Color Table VI in the labview\examples\Controls and Indicators\Graphs and Charts\Intensity Graphs and Charts for an example of color mapping.