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20000811: Unidata-Wisconsin datastream additions: CIMSS products (cont.)

>From: "D. J. Raymond" <address@hidden>
>Organization: NMT
>Keywords: 200008021927.e72JReT03751 ldm-mcidas pqact.conf ldmd.conf pnga2area

Dave,

>I would just like to continue the delta-encoded stuff through 15 August, so I 
>can make a clean break in archiving formats.

OK.  This will not be a problem given that you are not the holdup.

>One issue with new format is that the images are bigger,
>since they aren't compressed at all.

Right, but the PNG compressed ones are significantly smaller.  My tests
showed that the PNG compression of these images was overall best when
compared to delta-encoding, compress, gzip, and bzip2 (although bzip2
and PNG were close).

>I will either have to
>archive smaller time intervals on cdrom, or compress the images some other
>way, such as with gzip.

Why not save and archive the PNG compressed images?  They are, after all,
smaller than what you will end up with after a gzip.  This would only
take on additional entry in your LDM pqact.conf file.

>What images are likely to be more than 1 byte per pixel?

The GOES platforms (and POES, GMS, METEOSAT) provide two-byte data as a
matter of course.  The new TERRA satellites will also use multiple
bytes to represent pixel values.  We convert the UW stream images to
one-byte before broadcast, but there is a lot of pressure to leave the
ones accessible from the Unidata-Wisconsin archive in their original
form.  This is especially important when doing satellite research.  It
is not so important when using images for pattern recognition or wall
paper.

Tom

>From address@hidden Thu Aug 31 18:18:06 2000

   Unidata-Wisconsin Imagery Users:

   All delta-encoded imagery (decoded with lwtoa3) will be removed 
   from the Unidata-Wisconsin datastream at 18Z on Friday, September 15.

   PNG compressed versions of the same images have been include
   in the datastream since July 31, so there will be no interruption
   in service to sites that upgrade their ldm-mcidas decoders and
   LDM ldmd.conf and pqact.conf configurations.


Tom,

I'm converted.

Dave