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[Support #JXE-761208]: IDV with NetCDF including land (and IDV 2.7beta2)

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  • Subject: [Support #JXE-761208]: IDV with NetCDF including land (and IDV 2.7beta2)
  • Date: Tue, 02 Jun 2009 14:57:05 -0600
Hi Nickitas-

> We took efforts to make our NetCDF output for our NY/NJ Harbor ocean model
> CF-compliant, and now IDV renders it in 3D very nicely. We've seen probes,
> transects, volume rendering. Very cool!

Great!

> BUT,
> 
> 
> 
> Only if we create sub-arrays that do not include land (NaN lat-lon and out
> of range packed values). This is a coastal ocean model, and as such, land is
> part of the full output array. Because the grid is not a nice rectangle but
> quite distorted in the X-Y, lat-long coordinate values on land would be
> nonsensical. But if we try to load the full output NetCDF CF-compliant file
> with the native land/ocean array, IDV does not render in 3D. 

Is there a particular error that is generated?

My guess is
> that IDV is trying to render the land parts of the array that are NaN and
> fails,  because it does not know how to distinguish between contiguous areas
> of NaNs (such as land) versus internal NaN such as bad data, and does not
> know what to do with data gaps in general.
> 
> 
> 
> Any clues? Have you come up with any smart ways of dealing with this
> problem? By the way, IDV 2.7 beta 2 does not work at all for us, only 2.6,
> which is interesting in its own.

We definitely want to fix what's broke in 2.7b2, so could you point
me to a sample data file or upload one to:

http://motherlode.ucar.edu/repository/alias/idvupload

Once we get that fixed, I can look further into the other issue.  Having
NaN's for lat/lon is tricky because the netCDF layer translates that into
a lat/lon projection.  If there is a dimensionless vertical coordinate,
that complicates it further since we have to have a transformation between
lat,lon,sigma <-> lat,lon,alt for the 3D displays.

Don Murray

Ticket Details
===================
Ticket ID: JXE-761208
Department: Support IDV
Priority: Normal
Status: Open