Re: [idvusers] Cross-section of derived fields + multiple times = NullPointerException

  • To: Don Murray <dmurray@xxxxxxxxxxxxxxxx>
  • Subject: Re: [idvusers] Cross-section of derived fields + multiple times = NullPointerException
  • From: HansPeter Roesli <satmet.hp@xxxxxxxxxx>
  • Date: Sun, 23 May 2010 10:29:39 +0200
Hi Don -

Recently I have frequently been using a colour table partially that includes (semi-)transparent stretches. The colour scale displays correctly in the selection list of colour tables, i.e. you see the (semi-)transparent stretches. However, in all other instances (in the legend and when burnt into the display + other places?) the colour scale shows no transparency signature. It would be especially useful to have the signature in the display. Is this a bug or oversight?

cheers, HP

On 2010-05-21 17:29, Don Murray wrote:
Kevin-

Kevin R. Tyle wrote:
Thanks Don!  I need to keep you busy before you leave!!!

No rest for the weary. ;-)

Couple related questions:

1. Is there a way (or future plans for) to use a different vertical coordinate than height? Typically in a cross section one uses pressure as the y-axis.

It's on the todo list, but with Jeff and I leaving, it probably won't happen soon.

Also, when using isosurfaces with one parameter colored
by another, it would be nice to be able to have, say, the jet core colored by pressure in hPa instead of geopotential height in gpm.

For the colored-by parameter, you could select Formulas->Grid->Define a Grid Diagnostic and in the dialog enter the formula extractPressureFromNWPGrid(a). When prompted for A, pick any field in the data source that has pressure as it's vertical coordinate. This will create a pressure grid and then use it to color the wind speed isosurface.

2. Can parameters be scaled (aka like the SCALE parameter in GEMPAK) by powers of ten? Say I wish to display height values in decameters instead of meters?

Tom Whittaker wrote:
> In the Display Control, click on the "Edit" menu and "Change Display
> Unit".  For example, if the unit is "gpm", change it to "gpm*10".  You
> will have to change the contour interval stuff as well.  Hope that
> helps.

Tom is correct and you can use things like m*10E5. However, it should automatically adjust the contour values to the new unit (as best it can when the new unit is not just a scale e.g. K->degF).

If you always want decageopotential meters for height fields, you can use the Tools->Parameter Defaults Editor to set that, or once you have it displayed and have the units correct, select the File->Save->Save as Parameter Default from the control window to do that.

Don

On 05/21/2010 12:36 PM, Don Murray wrote:
Kevin-

Oh sure, just when we are about to do a release, you have to find a bug. ;-)

I've implemented a fix and it will be in the next nightly build (and the 2.9 release). Thanks for catching this.

To the list, we are planning a 2.9 full release next week. Please check out the test release at:

http://www.unidata.ucar.edu/downloads/idv/test

(or the nightly build) and let us know ASAP of any issues you find.

Don

Kevin R. Tyle wrote:
I've run into this problem where if I try to draw cross-sections on a derived field (e.g., potential temperature) and try to load more than one forecast time, the display will not appear and I get the following errors:

ERROR: Creating display: Color-Shaded Cross Section
java.lang.NullPointerException
java.lang.NullPointerException
at ucar.unidata.data.grid.GridUtil.setSpatialDomain(GridUtil.java:353) at ucar.unidata.data.grid.GridUtil.setSpatialDomain(GridUtil.java:333) at ucar.unidata.idv.control.CrossSectionControl.make2DData(CrossSectionControl.java:1736) at ucar.unidata.idv.control.CrossSectionControl.loadData(CrossSectionControl.java:1582) at ucar.unidata.idv.control.CrossSectionControl.loadDataFromLine(CrossSectionControl.java:1566) at ucar.unidata.idv.control.CrossSectionControl.applySmoothing(CrossSectionControl.java:1613) at ucar.unidata.idv.control.DisplayControlImpl.applyAttributesToDisplayables(DisplayControlImpl.java:1517) at ucar.unidata.idv.control.DisplayControlImpl.init(DisplayControlImpl.java:1066) at ucar.unidata.idv.ControlDescriptor.initControl(ControlDescriptor.java:987) at ucar.unidata.idv.ControlDescriptor$1.run(ControlDescriptor.java:912)
    at ucar.unidata.util.Misc$3.run(Misc.java:1089)

The problem also occurs with another derived field (Relative humidity), and with different NWP models, so I suspect this may be a general problem with "derived" quantitites. I've run this on both OSX and Linux 64-bit systems . . .

Thanks,

Kevin
______________________________________________________________________
Kevin Tyle, Systems Administrator               **********************
Dept. of Atmospheric & Environmental Sciences   ktyle@xxxxxxxxxxxxxxxx
University at Albany, ES-235                    518-442-4578 (voice)
1400 Washington Avenue                          518-442-5825 (fax)
Albany, NY 12222                                **********************
______________________________________________________________________

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fn:HansPeter Roesli
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org:EUMETSAT Satellite Meteorology Consultant
adr;quoted-printable:;;via Monte Br=C3=A8 5;Locarno;;CH-6605;Switzerland
email;internet:satmet.hp@xxxxxxxxxx
tel;work:+4179 292 0706
tel;home:+4191 751 3650
tel;cell:+4179 292 0706
url:www.eumetsat.int
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