[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

[netCDFJava #XIR-445342]: Problem with netCDF-Java CoordinateAxis returning wrong values

Hi all:

it looks to me the CDM handles the 2 identically. The difference may be that 
the NN lons happen to span >= 360 (?)

John

> Good Monday, Sean...
> 
> I have tested the two files on the IDV nightly from today, and as I
> suspected the behavior is different:
> 
> When I display the data from the "NSS.GHRR.NF... ", a "projection" is
> created and the "auto-set projection" works as expected.
> 
> When I display the data from the "NSS.GHRR.NN..." file, no
> "projection" is created.
> 
> In both cases, I note that the Field Selector "Region" tab does show
> the proper outline of the domain.
> 
> Finally, as far as I can tell, the two files have identical
> structures, just the size and coverage are different.
> 
> The effect of this is that within McV, the display used for the
> Scatter Plot does not show the plan view of the data for the "NN"
> file.  It does show the data for the "NF" file, thanks to the first
> round of changes John made.
> 
> Both files are still on our ftp site
> (ftp://ftp.ssec.wisc.edu/pub/ssec/tomw/) but if you can't get them (I
> think they "expire" today or tomorrow), just let me know.
> 
> Thanks...from hot and sunny MSN...
> 
> tom
> 
> 
> On Thu, Jul 11, 2013 at 10:46 PM, Tom Whittaker <address@hidden> wrote:
> > Hi Sean....
> >
> > Thanks for checking this out.   I won't be back in the office until
> > Monday and I will write you back then.  I want to reconfirm my
> > observations between the file you've been testing with and the
> > previous one (the original one that we had problems with).    I
> > appreciate you checking into this....I will be in touch.
> >
> > tom
> >
> >
> > On Thu, Jul 11, 2013 at 3:15 PM, Unidata netCDF Java Support
> > <address@hidden> wrote:
> >> Hi Tom,
> >>
> >> I've loaded the file into the IDV using 3.1u1, 4.0u1, and the latest 
> >> version
> >> from master, and I can't see a difference between any of them. If I view 
> >> the
> >> file using the South Pole Projection, then it looks great. The DataProbe 
> >> also
> >> seems to be working the same in all three as well.
> >>
> >> You mentioned in another email that the IDV isn't able to set a projection
> >> from the display. The reason is that there isn't any projection information
> >> in the file, likely because lat / lon are the only coordinate variables in
> >> the file.
> >>
> >> I guess overall I am confused as to what the issue is. I mean, I see that 
> >> the
> >> lat / lon returned from the CoordinateAxis is different from those in the 
> >> file,
> >> but as John said, these are "enhanced" since you are going through
> >> NetcdfDataset. At any rate, I can't tell if the IDV is having any issues 
> >> with
> >> this, given that everything seems to behave the same, from a IDV
> >> users perspective, between 3.1u1, 4.0u1, and master.
> >>
> >> Could you give us more info on the application in which the values returned
> >> from CoordinateAxis is messing things up?
> >>
> >> Thanks!
> >>
> >> Sean
> >>
> >>> Hi John....
> >>>
> >>> I've started to evaluate the changes....and unfortunately, there are
> >>> some ripple effects -- some things just are not working.
> >>>
> >>> In thinking about this, shouldn't it be the responsibility of the
> >>> drawing routine to sort out the "seams"?  I am concerned (more so
> >>> now...) that the netCDF library is changing values handed back to the
> >>> caller when none of the metadata says do that.  My gut is telling me
> >>> that is not the "right" thing to do...the values in the file (as
> >>> modified only by missing code, the
> >>> offset and the scaling, if applicable) should be returned to the
> >>> caller, not something that "magically" is done.
> >>>
> >>> While it might be a nice "service" to provide for some applications,
> >>> perhaps the proper way is to introduce some attribute that says
> >>> "please_fix_my_seams"; otherwise leave the values sacrosanct....
> >>>
> >>> What do other people think?
> >>>
> >>> tom
> >>>
> >>> On Wed, Jul 3, 2013 at 3:30 PM, John Caron <address@hidden> wrote:
> >>>
> >>> > what we are doing is converting from lat/lon with valid range +- 180 to
> >>> > coordinate values which "removes the seam" from the coordinates (by 
> >>> > adding
> >>> > +- 360) , so that the drawing routines dont have to worry about the
> >>> > coordinates jumping. so the valid_range of the original coords doesnt 
> >>> > matter
> >>> > here.
> >>> >
> >>> > in fact the problem is that the longitude on row 6614 jumps 110 degrees,
> >>> > when i had a max jump of 100 degrees. i have adjusted the algorithm 
> >>> > again,
> >>> > now that row has (just the last 40 values):
> >>>
> >>> --
> >>> Tom Whittaker
> >>> University of Wisconsin-Madison
> >>> Space Science & Engineering Center (SSEC)
> >>> Cooperative Institute for Meteorological Satellite Studies (CIMSS)
> >>> 1225 W. Dayton Street
> >>> Madison, WI  53706  USA
> >>> ph: +1 608 262 2759
> >>>
> >>>
> >>
> >>
> >> Ticket Details
> >> ===================
> >> Ticket ID: XIR-445342
> >> Department: Support netCDF Java
> >> Priority: Urgent
> >> Status: Open
> >>
> >
> >
> >
> > --
> > Tom Whittaker
> > University of Wisconsin-Madison
> > Space Science & Engineering Center (SSEC)
> > Cooperative Institute for Meteorological Satellite Studies (CIMSS)
> > 1225 W. Dayton Street
> > Madison, WI  53706  USA
> > ph: +1 608 262 2759
> 
> 
> 
> --
> Tom Whittaker
> University of Wisconsin-Madison
> Space Science & Engineering Center (SSEC)
> Cooperative Institute for Meteorological Satellite Studies (CIMSS)
> 1225 W. Dayton Street
> Madison, WI  53706  USA
> ph: +1 608 262 2759
> 
> 


Ticket Details
===================
Ticket ID: XIR-445342
Department: Support netCDF Java
Priority: Urgent
Status: Open