Stream lines  

General options

Color Mode: Allows the user to define the colors used to paint the stream lines:
Monochrome: All the stream lines are drawn with the same color, which can be adjusted with 'Change color'.
Color: Allows the definition of the color of the monochrome stream lines.
Stream contour filled: The color of the streamlines changes, ala Contour Fill according to the modulus of the vector used to create the stream line.
Result contour filled: The stream lines are drawn with the color scale of the current contour fill, i.e., the current contour fill is also drawn over the stream lines. If no contour fill is displayed, then the monochrome color is used.

Label: This option lets you select the kind of label:
None: No labels are drawn.
0-End: Labels are drawn according to the following convention: 0 at the start of the stream line, and the total time taken for the particle to travel at the end.
Ini-End: Labels are drawn according to the following convention: 0 at the chosen point, with - time before at the beginning of the stream line and + time after at the end.
Maximum length: To avoid infinite curves (e.g. in vortex).
Maximum points: To avoid curves with excessive (and memory expensive) number of points.

Stream lines render options

Line size: determine the thickness of the line given as a pixel factor.
Quality: the stream line can be drawn using a line element (Quick) or a volumetric element (Nice). Nice is slower than Quick.

If the Quality option selected is Nice the following options can be selected to draw:

Detail: Defines how the stream lines are drawn, ie. which volumetric element is used:
Points: showing the points calculated for the stream lines and used to draw them.
Ribbons: stream ribbons showing the swirl of the velocities field.
Set initial rotation: Sets the initial rotation of the stream ribbons at the selected nodes.
4 sided prisms: stream 'tubes' with constant width based on a 4 sided prisms.
8 sided prisms: stream 'tubes' with constant width based on a 8 sided prisms.

Show arrows: With this option GiD draws arrows on the stream lines showing the sense of them.
Monocolor: Defines the color of the arrows when the color mode of the stream lines is monochrome.
Size: The size of the arrows.
Spacing: The space between the arrows.