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[IDV #RCR-783387]: Odd grid data generation behavior...

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  • Subject: [IDV #RCR-783387]: Odd grid data generation behavior...
  • Date: Thu, 29 Jan 2009 10:16:36 -0700
Hi Tom-

> >> Sometimes the domain of the adapted FlatField is a Linear2DSet,
> >> sometimes it's a Gridded2DSet.  The data has a projection, in this
> >> VerticalPerspective, so I'm at a loss to understand why a GriddedSet
> >> is needed *sometimes*.  In fact, a GriddedSet is only used when
> >> a stride is applied, and even then, not all of the time.  This is a
> >> potential performance hit for NetCDF files that have large dimensioned
> >> grids.
> >>
> >
> > That's all handled down in GeoGridAdapter.  Maybe the striding is
> > screwing up the determination of linearity?  If you run the
> > IDV with -debug, you'll get some printouts from GeoGridAdapter
> > on what it has determined is needed.  If you can give some examples,
> > I can look further.

> > A linear set is used if it can determine that
> > the coordinate axes are linear and the Z dimension is > 1 (if there
> > is a Z coordinate).  Single level grids (3D on 2D manifold) have to
> > be GriddedSets or we get weird displays.
> >
> I understand that, but this file only contains (x,y)->Q, where x,y->lon,lat
> according to proper NetCDF conventions.  I'm sure this is a memory
> hit, but maybe it's more of a 'back-burner' thing for now.

The axes are not linear which is why a Gridded2DSet is created.

For example, the first 5 numbers in the west-east coordinate are:

-4365.84, -4363.806, -4361.771, -4359.736, -4357.702

with intervals 2.034, 2.035, 2.035, 2.034  between them.

This fails the checkLinearity check.

Don


Ticket Details
===================
Ticket ID: RCR-783387
Department: Support IDV
Priority: Normal
Status: Open