RE: GDAL NetCDF driver and projection.

• To: "Denis Nadeau" <denis.nadeau@xxxxxxxxx>, "John Caron" <caron@xxxxxxxxxxxxxxxx>
• Subject: RE: GDAL NetCDF driver and projection.
• From: "Steve Kopp" <skopp@xxxxxxxx>
• Date: Fri, 28 Apr 2006 08:08:48 -0700

Denis,

After discussions with John last year, this is the same approach we have
taken with ArcGIS when exporting to netCDF, and so far it is working
well for us.

When we export to a netCDF file we write projection information as an
attribute of a variable. We call the attribute "esri_pe_string". Of
course we are reading and writing the CF standard projection information
when it is a coordinate system supported by CF.

Steve

float wdemclputm(y, x) ;

                  wdemclputm:long_name = "wdemclputm" ;

                  wdemclputm:esri_pe_string =
"PROJCS[\"Clarke_1866_UTM_Zone_12N\",GEOGCS[\"GCS_Clarke_1866\",DATUM[\"
D_Clarke_1866\",SPHEROID[\"Clarke_1866\",6378206.4,294.9786982]],PRIMEM[
\"Greenwich\",0.0],UNIT[\"Degree\",0.0174532925199433]],PROJECTION[\"Tra
nsverse_Mercator\"],PARAMETER[\"False_Easting\",500000.0],PARAMETER[\"Fa
lse_Northing\",0.0],PARAMETER[\"Central_Meridian\",-111.0],PARAMETER[\"S
cale_Factor\",0.9996],PARAMETER[\"Latitude_Of_Origin\",0.0],UNIT[\"Meter
\",1.0]]" ;

From: owner-galeon@xxxxxxxxxxxxxxxx
[mailto:owner-galeon@xxxxxxxxxxxxxxxx] On Behalf Of Denis Nadeau
Sent: Thursday, April 27, 2006 6:51 AM
To: John Caron
Cc: galeon@xxxxxxxxxxxxxxxx; CF
Subject: Re: GDAL NetCDF driver and projection.

Hi John,

Thank you for taking the time to write this email.  Your points are very
clear, and they are very helpful.  I must tell you that you give me
information and that you sure taught me about CF-1 convention community
.  I will keep your email as a reference when coding the GDAL  NetCDF

driver.

I have decided to use WKT to encode projections and if I see a new
governance structure from CF checked in, I will update the driver.  As
well, I think for this time being I will relax the lat,lon array
requirements.  If needed by the community, it would be very easy to
compute, but I do not want the driver to be expensive in CPU and space.

Thanks again,

Regards,
Denis

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  • Re: GDAL NetCDF driver and projection.
    • From: Denis Nadeau