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[ferret_users] vector, flowline and density

Hi everyone,

I have a question about the use of the command "VECTOR/flowline".
With something as simple as this:

shade temperature,lon,lat
vector/overlay/flowline u,v,lon,lat

I have been trying to draw a 2D wind field over a 2D temperature field, without any success 
so far apart from loosing hair.
The temperature is just plotted with SHADE. The wind field is drawn from the variables u and 
v and I want it to appear as a flow line instead of the well known arrows.
The latter is the tricky part: I can easily get the flow lines, but I can not decrease the number 
of drawn flowlines. They are so many that the graphic is not legible at all (see attached 
screen capture which is the best i could get so far).

Until now, I have tried:
- the "/density=..." qualifier. The bigger the number, the more numberous the flow lines are. 
The best I could get is with a decimal number (any of them) between 0.1 and 0.9. Negative 
numbers are not of any help.
- the "/xskip=.../yskip=..." qualifiers. Except if the wind field is drawn as arrows instead of 
flowlines, it doesn't change anything to the graph. I even tried the "pplus/...,xskip,yskip" 
formula, unsuccessfully.
- the "/length=..." qualifier. That doesn't work.
- different amusing combinations of all possible qualifiers, without any success.
- a different way to give my variables u and v. I indicated u
[x=-1000:1000:100,y=-1000:1000:100] (units=km), idem for v, hoping Ferret would be 
forced to use only a sample of u and v, but that didn't work either.

Does anyone have a solution for that?
By the way, I couldn't reduce the size of the arrows drawn on the flowline, any hint about this 
would be very welcomed too!

Thanks in advance for any help,


P.S.: I am using Ferret v5.81 on a Linux(g77) 2.4.18, according to the Ferret header.

Attachment: Image 1.png
Description: PNG image

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