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

Re: 20040713: easy TOOLS needed RE: nc file into xyz or ArcView

>To: <address@hidden>
>cc: <address@hidden>
>From: "Falk Huettmann" <address@hidden>
>Subject: easy TOOLS needed RE: nc file into xyz or ArcView
>Organization: Biology & Wildlife Dept., Inst. of Arctic Biology UAF
>Keywords: 200407140343.i6E3haaW008547 netCDF GIS

Hi Dr. Huettmann,

> you have a really great datasets, but you make the extraction and use 
> so clumsy that nobody can use it, unless one applies C, FORTRAN, PERL
> etc.
> 
> For instance, you had a version where one could use ASCII data in a X,Y
> and Z format, e.g. to be used for a ArcView GIS import.
> 
> This is one THE major applications by the public, I even did my PhD
> about it and with your data in 1999, and now even I cannot get the data
> anymore.
> 
> With your current policy you hide data, but do NOT make them available
> to the public.
> 
> This is now my second request for help actually.
> 
> I once obtained an EXE called ANALYXYZ.EXE for you which I cannot see
> anymore on the WWW and which does not work on the otemp.anal1deg.nc
> 
> I am shocked; are we all going downhill now ?

The netCDF data model and binary data format have some significant
advantages over ASCII data, which is why many data providers in the
earth sciences choose to use netCDF instead of ASCII.  The primary
advantage is the possibility of direct-access, so that a small subset
of a large dataset may be accessed efficiently, without first reading
through all the preceding data.  Another advantage is provision of
common ways to represent metadata, so that more of the meaning of data
can be captured in a way that analysis and visualization programs can
make use of.

However, you're right that it has been difficult to access netCDF data
from GIS applications.  There is some good news about this.  Several
GIS systems already include netCDF data access from the GIS
application, or will soon do so.  For example, here's a summary of a
phone call I got last month about ESRI including netCDF access in
their software:

  This morning I got a call from David Maidment (a leading authority on
  water resources and GIS, author of ArcHydro, and professor at UT
  Austin) who had just been talking with Steve Kopp (a senior ESRI
  developer) about results from a meeting we participated in at ESRI
  last week, organized by Dr. Maidment.  At the meeting, I gave a
  presentation on netCDF and had a separate hour-long discussion with
  Scott Morehouse (ESRI's Director of Software Development and
  "visionary on advancing the theory and practice of GIS" according to
  the ESRI's "Modeling Our World" publication).  Jack Dangermond, ESRI's
  founder and CEO, was also involved in some of the discussion.

  According to Maidment, ESRI has since determined to add netCDF access
  to their products, allowing them to read, view, and query netCDF data.
  It's now on their immediate agenda, and may make it into an upcoming
  release.

  I had suggested that they handle georeferencing problems by specifying
  that datasets must comply with particular netCDF conventions to be
  accessible from ESRI products, such as the CF Conventions
  <http://www.cgd.ucar.edu/cms/eaton/cf-metadata/CF-1.0.html> or the
  somewhat wider set of conventions supported by John Caron's GeoGrid
  class.

  This will simplify integrating geoscience datasets with GIS systems
  and is about the best outcome we could have hoped for, certainly
  better than using a whole-file conversion approach, or using geoTIFFs
  as a bridge format.

As another example, GDAL (Geospatial Data Abstraction Library),
written by Frank Warmerdam now has support for netCDF data access:

  http://gdal.maptools.org/frmt_various.html#netCDF

Finally, the next release of netCDF (3.6.0) will have much better
support for Windows. .NET, and even access to netCDF data from Visual
Basic.  We may be going downhill in other ways :-), but I hope this
represents some progress in making scientific data more accessible.

Regards,
Russ Rew

_____________________________________________________________________

Russ Rew                                         UCAR Unidata Program
address@hidden          http://www.unidata.ucar.edu/staff/russ