[IDV #UPY-185961]: Vector Cross Section

Hi Donna-

> My inquiry has to do with plotting model output winds with the Vector
> Cross Section Display.  As far as I can see, what I want to do is not
> possible with the current capabilities of IDV.  If this is true, then
> consider the following to be feature requests.

It'll be a little of both.  The instructions below are for version 
2.0 which we just released.

> 1) Adjust the vertical scale of the vector cross section.  Instead of
> the 0-16000m that comes up by default, I would like to see 0-4000m at
> higher resolution.  The vertical model fields will support this
> increased resolution.

It depends whether you mean the cross section display in the
main display or in the separate window.

If the latter, it's on our list of things to do but there's another
way to skin the cat (see below).  If it's the former, you could 
change the vertical scale in the main display and set clipping
on (View->Show->Clip at Box menu).

As for the other way to skin this cat, you could use the Transect Display
to show the contours (and overlay other parameters).  This is a newer
feature (starting in 1.3b2).  To use this, go to the File->New->Display
Window->Misc->Transect and Map menu to bring up a Transect Display
with a map.  Minimize or close any other display windows.  Click on
the Transect Display to set it active and then load in your cross section.
On the Transect Display, use the View->Vertical Scale menu to set
the vertical scale to what you want.  You can change the transect location
using the Transects->Edit menu.  That will show the current transect
in the map display.  You can use the Transect Control to add new transects
or move the currently displayed one.  See the section in the IDV
User's Guide for more information on using the Transect Display and
Transect Control.  You could add other paramters to the display as well.

> 2) Color code the vectors by wind speed.  E.g. vectors 10-19 m/s would
> be green, 20-29 would be yellow, 30-39 would be red...

Normally, I'd say this could be done, but it looks like there is a
bug doing this for the vertical cross sections.  You get the award
for uncovering the first bug of version 2.0.

You can do this for Wind Barb Plan Views (or vectcors) using
the System->One value colored by another formula.

- from the Field Selector, choose the Formulas Data Source and
right click on the System->One value colored by another formula. 
This will pop up a menu and you should choose the "Evaluate and Save" 
option.
- From the Field Selector that pops up, select the 
parameters you want colored by another.  For the Data Field, 
choose the vector field (e.g. True Wind vectors) you want to use.  
For the Color Field, select Windspeed and then click OK.  The
IDV will read in the data and combine the fields.  When it's
done, you will be prompted for a name.  Either keep the default
or put in something like "vectors colored by speed".  This will
add a Cached Data  data source to the Field Selector.
- From the Field Selector, choose the Formulas Data source and the
System->Any Field formula and the Flow Display (except cross section)
that you want to use.  We need to use the Any Field formula so we 
can select the appropriate display.  Click the Create Display button.
- When the Field Selector pops up, choose the Cached Data field
that you saved previously.
- Also, it looks like there's a problem with the default range
for the color table in this case.  It looks like it's using the
range for the u component rather than the wind speed.  You can
change the color table range by right clicking on the color bar
in the legend and using the Change Range dialog.

We'll get the vertical cross section bug fixed for the next
release (probably October).

> I have a specific application in mind and I am planning ahead.  It
> would be nice to see it anytime but I really intend to make extensive
> use of it in about 9-10 months.

Okay.  Let me know if you have questions on the steps above.

Ticket Details
===================
Ticket ID: UPY-185961
Department: Support IDV
Priority: Normal
Status: Open