[IDV #WHS-790529]: Issue with bottom velocity vectors

Hi Rich,

I have been revisiting some old issues over the last few days; things that were
left dangling over the last while (months, even years) but did not have time to
get back to.

At any rate, I played around with this specific issue over the weekend. The core
problem is the IDV does not handle the vertical coordinate system (bathymetry,
s_rho) properly which leads to those visualization artifacts of missing swaths
of data. The data appear to get smushed into the earth surface. You notice this
when doing a side view of the data. It does not have anything to do with the
data (why would it as Python demonstrates), nor is it a VisAD issue.

Please see the link below where I give a fake and exaggerated vertical
coordinate system in 'fixed.ncml', and 'fixed.xidv'. The flow vectors now plot
correctly. This kludge can be used as a workaround.

(See ncml.diff for the changes I had to make to the NCML.)

http://motherlode.ucar.edu/repository/entry/show?entryid=d93cf4b3-b868-49a5-b49c-f5358e426346
 
If looking at the xidv bundles, you may have to alter paths to point to the
correct NCML path.

This problem had been bugging me for a while and I wanted to get back to it.

Best,

Unidata IDV Support



> > Yuan,
> > Mine still looks strange (different, but strange).
> >
> > Can you please send me your bundle that works?
> >
> > Thanks,
> > RIch
> 
> 
> Rich,
> The attached bundle using the Match Display Region in the region subset 
> panel, I also try used a selected a region option and worked.
> 
> 
> Yuan
> >
> > On Tue, Jul 7, 2015 at 2:37 PM, Unidata IDV Support
> > <address@hidden> wrote:
> > >> Yuan,
> > >> Just to clarify:
> > >>
> > >> You are saying that the velocity vectors WILL PLOT CORRECTLY if we DO
> > >> NOT restrict to a bounding box?
> > >>
> > >> -Rich
> > >
> > > Rich,
> > >         With this dataset, if you want to get the "correctly" result, you 
> > > need to spatial subset. I don't know why. In your previous bundle, you 
> > > did not
> > > do any subset in the region and you were getting bad result.
> > >
> > >
> > > Yuan
> > >>
> > >> On Tue, Jul 7, 2015 at 2:29 PM, Unidata IDV Support
> > >> <address@hidden> wrote:
> > >> >> By spatial subset, do you mean the subsetting like plotting every
> > >> >> other vector, or do you mean subsetting like restricting the region to
> > >> >> a specified bounding box?
> > >> >>
> > >> >
> > >> > I mean do not restrict to a bounding box, if you did spatial subset in 
> > >> > the IDV (by bounding box or match display region), the result would be 
> > >> > good.
> > >> >
> > >> >
> > >> > Yuan
> > >> >> On Tue, Jul 7, 2015 at 11:33 AM, Unidata IDV Support
> > >> >> <address@hidden> wrote:
> > >> >> >> Rich,
> > >> >> >>
> > >> >> >> When I create my own bundle for these data, I see essentially no
> > >> >> >> difference between IDV and Python. See attached bundle and images.
> > >> >> >>
> > >> >> >> Best,
> > >> >> >>
> > >> >> >> Unidata IDV Support
> > >> >> >>
> > >> >> >
> > >> >> > Rich,
> > >> >> >
> > >> >> >      Somehow I noticed that the results in the IDV were different 
> > >> >> > with and without the spatial subset, even if the spatial subset 
> > >> >> > covers the whole dataset.
> > >> >> > Would you be able to verify this in the Python?
> > >> >> >
> > >> >> >
> > >> >> >
> > >> >> > Yuan
> > >> >> >>
> > >> >> >> > > Yuan,
> > >> >> >> > > So when you run my bundle, do you get the same result?
> > >> >> >> > > -Rich
> > >> >> >> > >
> > >> >> >> >
> > >> >> >> > When I ran the bundle, I got even worst result. My feeling is 
> > >> >> >> > that those missing vectors were likely associated with very 
> > >> >> >> > small values. If you draw wind barb, you will get every points.
> > >> >> >> >
> > >> >> >> >
> > >> >> >> > Yuan
> > >> >> >> > > On Thu, Jul 2, 2015 at 11:54 AM, Unidata IDV Support
> > >> >> >> > > <address@hidden> wrote:
> > >> >> >> > > >> We are running 5.1u2.   Did you look at the bundle?  All 
> > >> >> >> > > >> your
> > >> >> >> > > >> questions are answered by the bundle, no?
> > >> >> >> > > >
> > >> >> >> > > >
> > >> >> >> > > > Rich,
> > >> >> >> > > >         I have no problem getting the result similar to the 
> > >> >> >> > > > python output. See the attached. However, your bundle does 
> > >> >> >> > > > look very strange, almost like some kind of
> > >> >> >> > > > filter working there. I will check and let you know.
> > >> >> >> > > >
> > >> >> >> > > >
> > >> >> >> > > > Yuan
> > >> >> >> > > >>
> > >> >> >> > > >> On Wed, Jul 1, 2015 at 5:34 PM, Unidata IDV Support
> > >> >> >> > > >> <address@hidden> wrote:
> > >> >> >> > > >> > Rich,
> > >> >> >> > > >> >
> > >> >> >> > > >> > Here are a few comments:
> > >> >> >> > > >> >
> > >> >> >> > > >> > - Update your IDV to the latest version (5.1u2, this will 
> > >> >> >> > > >> > yield no improvement
> > >> >> >> > > >> > probably, but it is usually best to work with the latest 
> > >> >> >> > > >> > version of the IDV).
> > >> >> >> > > >> >
> > >> >> >> > > >> > - For clarification, the flow vectors are supposed to be 
> > >> >> >> > > >> > derived from what? The
> > >> >> >> > > >> > data contain two u and v fields (momentum versus stokes). 
> > >> >> >> > > >> > Which one are you
> > >> >> >> > > >> > interested in? (I wonder if there is confusion/mismatches 
> > >> >> >> > > >> > going on here.)
> > >> >> >> > > >> >
> > >> >> >> > > >> > - Are you sure you are looking at the same geographic 
> > >> >> >> > > >> > extents? The IDV is
> > >> >> >> > > >> > displayed roughly over NY harbor. I cannot tell where the 
> > >> >> >> > > >> > Python plot is
> > >> >> >> > > >> > located.
> > >> >> >> > > >> >
> > >> >> >> > > >> > - I wonder if there are numerical errors going on. One of 
> > >> >> >> > > >> > the Derived Fields in
> > >> >> >> > > >> > the IDV is "Speed (from U & V)".  When you do a "Value 
> > >> >> >> > > >> > Plot" of these data, do
> > >> >> >> > > >> > you get numbers you expect?
> > >> >> >> > > >> >
> > >> >> >> > > >> > - Experiment with the Flow Vector Control in the IDV 
> > >> >> >> > > >> > Dashboard, Displays Tab.
> > >> >> >> > > >> >
> > >> >> >> > > >> > Keep us up-to-date on your progress.
> > >> >> >> > > >> >
> > >> >> >> > > >> > Best,
> > >> >> >> > > >> >
> > >> >> >> > > >> > Unidata IDV Support
> > >> >> >> > > >> >
> > >> >> >> > > >> >
> > >> >> >> > > >> >
> > >> >> >> > > >> >
> > >> >> >> > > >> >> IDV Gurus,
> > >> >> >> > > >> >>
> > >> >> >> > > >> >> We are struggling to get bottom velocity vectors 
> > >> >> >> > > >> >> displayed properly in
> > >> >> >> > > >> >> IDV (5.0u2) for a Hurricane Sandy ocean simulation.
> > >> >> >> > > >> >>
> > >> >> >> > > >> >> The bottom velocity for 2012-10-30 00:00:00 should look 
> > >> >> >> > > >> >> like the 1st
> > >> >> >> > > >> >> attached image (plotted in python using this notebook):
> > >> >> >> > > >> >> http://nbviewer.ipython.org/gist/rsignell-usgs/a85e68a71933910a171a
> > >> >> >> > > >> >>
> > >> >> >> > > >> >> but instead it looks like the 2nd attached image.
> > >> >> >> > > >> >>
> > >> >> >> > > >> >> In the IDV image you can see that the flow at the coast 
> > >> >> >> > > >> >> is the wrong
> > >> >> >> > > >> >> direction, and there are those strange black areas with 
> > >> >> >> > > >> >> no vectors.
> > >> >> >> > > >> >>
> > >> >> >> > > >> >> What is going on here?
> > >> >> >> > > >> >>
> > >> >> >> > > >> >> I'm attaching the bundle so you can recreate this 
> > >> >> >> > > >> >> yourself.
> > >> >> >> > > >> >> --
> > >> >> >> > > >> >> Dr. Richard P. Signell   (508) 457-2229
> > >> >> >> > > >> >> USGS, 384 Woods Hole Rd.
> > >> >> >> > > >> >> Woods Hole, MA 02543-1598
> > >> >> >> > > >> >>
> > >> >> >> > > >> >>
> > >> >> >> > > >> >
> > >> >> >> > > >> >
> > >> >> >> > > >> > Ticket Details
> > >> >> >> > > >> > ===================
> > >> >> >> > > >> > Ticket ID: WHS-790529
> > >> >> >> > > >> > Department: Support IDV
> > >> >> >> > > >> > Priority: Normal
> > >> >> >> > > >> > Status: Closed
> > >> >> >> > > >> >
> > >> >> >> > > >>
> > >> >> >> > > >>
> > >> >> >> > > >>
> > >> >> >> > > >> --
> > >> >> >> > > >> Dr. Richard P. Signell   (508) 457-2229
> > >> >> >> > > >> USGS, 384 Woods Hole Rd.
> > >> >> >> > > >> Woods Hole, MA 02543-1598
> > >> >> >> > > >>
> > >> >> >> > > >>
> > >> >> >> > > >
> > >> >> >> > > >
> > >> >> >> > > > Ticket Details
> > >> >> >> > > > ===================
> > >> >> >> > > > Ticket ID: WHS-790529
> > >> >> >> > > > Department: Support IDV
> > >> >> >> > > > Priority: Normal
> > >> >> >> > > > Status: Open
> > >> >> >> > >
> > >> >> >> > >
> > >> >> >> > >
> > >> >> >> > > --
> > >> >> >> > > Dr. Richard P. Signell   (508) 457-2229
> > >> >> >> > > USGS, 384 Woods Hole Rd.
> > >> >> >> > > Woods Hole, MA 02543-1598
> > >> >> >> > >
> > >> >> >> > >
> > >> >> >>
> > >> >> >
> > >> >> >
> > >> >> > Ticket Details
> > >> >> > ===================
> > >> >> > Ticket ID: WHS-790529
> > >> >> > Department: Support IDV
> > >> >> > Priority: Normal
> > >> >> > Status: Closed
> > >> >> >
> > >> >>
> > >> >>
> > >> >>
> > >> >> --
> > >> >> Dr. Richard P. Signell   (508) 457-2229
> > >> >> USGS, 384 Woods Hole Rd.
> > >> >> Woods Hole, MA 02543-1598
> > >> >>
> > >> >>
> > >> >
> > >> >
> > >> > Ticket Details
> > >> > ===================
> > >> > Ticket ID: WHS-790529
> > >> > Department: Support IDV
> > >> > Priority: Normal
> > >> > Status: Open
> > >> >
> > >>
> > >>
> > >>
> > >> --
> > >> Dr. Richard P. Signell   (508) 457-2229
> > >> USGS, 384 Woods Hole Rd.
> > >> Woods Hole, MA 02543-1598
> > >>
> > >>
> > >
> > >
> > > Ticket Details
> > > ===================
> > > Ticket ID: WHS-790529
> > > Department: Support IDV
> > > Priority: Normal
> > > Status: Open
> > >
> >
> >
> >
> > --
> > Dr. Richard P. Signell   (508) 457-2229
> > USGS, 384 Woods Hole Rd.
> > Woods Hole, MA 02543-1598
> >
> >
> 


Ticket Details
===================
Ticket ID: WHS-790529
Department: Support IDV
Priority: Normal
Status: Closed