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Re: Format of your CONUS mosaic?

Tyler,

The 1km images I produce are GINI format headers, just as the NOAAPORT
satellite data are.

I have flagged the compression flag in the GINI header with a value of
128 to designate if PNG compression is used to pack the image block
using PNG (8 bit).
Compression is an option in nex2gini. If the compression flag is 0, then
the data is uncompressed and a standard raster as the un-zlib compressed
GINI images are.
I also provide a calibration block in the GINI header to relate the
0-255 values to
calibrated units.

I also provide the 1km gridded data as a grib2 product in the FNEXRAD
data feedwith the nat_hr eg national high res string in the identifier
which may
be a better fit for using the data in other locations instead of as an
image.

Steve Chiswell
Unidata User Support


On Thu, 2007-09-13 at 11:29 -0500, Tyler Allison wrote:
> Steve,
> 
> Mike of Gibson Ridge (the developer of the GRx line of radar software
> products) had asked me about the details of the 1km CONUS composite that's
> out on the LDM/Unidata feed and I couldn't answer his questions.
> 
> But I seem to recall that you are the generator of that composite.  Can
> you answer his questions below?  All I've ever done with the files is run
> them through Gempak ;)
> 
> I suspect Mike is wanting to rip open the file "raw" and go after the data
> directly instead of through some kind of library or conversion routine
> within Gempak.  Thus his comments about the headers. I've included Mike on
> this email.  His questions below....
> 
> > I looked at the n0r_20070912_1159 file out there and it's in a strange
> > format. I vaguely remember seeing this "TICZ99 CHIZ" header type but don't
> > remember what it means. I also see PNG header information after the header
> > so I assume that's the image information. Couple of things:
> >
> > 1) What is the official type of these files? What's in the header?
> >
> > 2) What format is the image in each file (eg. 8bit or 24bit)? Even with
> > internal PNG compression, the files are an order of magnitude larger than
> > equivalent natcomp files on iastate.edu. Here's a link to the iastate.edu
> > natcomp files:
> >
> > http://mesonet.agron.iastate.edu/data/gis/images/unproj/USCOMP/
> >
> 
> 
-- 
Steve Chiswell <address@hidden>
Unidata