Displaying Barbs using the Flow Tab

An an alternative to using the Barbs tab, the Flow tab can also be used to place arrows based on flow speed and direction.  The Flow tab can color the barbs according to the various colorings available in the Flow tab.  To produce barbs from flow settings, the user must modify the steady flow settings as follows:

• Set "Steady integration direction" to "Forward"
• Under Appearance settings, un-check "Automatically scale steady field".  This enables two settings "Samples per flow line" and "Steady Field Scale Factor"
• Set "Samples per flow line" to 2 (the minimum)
• Set the Shape to "Arrow"
• Enable the flow.  Adjust the "Steady Field Scale Factor" until the arrows (barbs) are the desired length.

One barb will originate at each of the seed points.  Adjust the flow rake (or list of seeds) to position the barbs as desired.

The color of the barbs will be determined by the appearance settings.  By adjusting the flow color mapping, the barbs can be colored by a variable mapping or by seed index.

Note that the barbs produced by this technique are interpolating the fleld between the start position and a subsequent point along the associated streamline.  Therefore these barbs will be slightly different in direction and length from arrows that are based solely on the field values at the starting position of the barb.