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20050310: NEXRAD data transformation



>From: address@hidden
>Organization: GMU
>Keywords: 200503110302.j2B32Tv2006037 McIDAS FNEXRAD composite

Hi Ying,

>I'm interested in NEXRAD composite data and have a question:
>
>I want the composite data (the U.S. extent, not regional data), and I found
>the qualified feedtype is FNEXRAD. the files I got is not big, i.e. 52k for 2km
>n1p data. I believe it's in GINI format. Please correct me if any thing wrong.

The data that is broadcast is PNG compressed GINI:  the header is not 
compressed,
but the image portion is.

>How can I use the McIDAS facility to transform it to GeoTIFF format?

Virtually the same way that you did for the GOES imagery:

1) run the ldm-mcidas decoder pngg2gini from a pqact.conf action to 
   uncompress the images into straight GINI format

2) create an ADDE dataset using the uncompressed images as the data store
   (this is done in LSSERVE.BAT as the NEXRCOMP group)

3) remap the images into RECTilinear projection

4) copy the images to a GeoTiff output dataset.

>From LSSERVE.BAT I can not find any example for this feedtype...

The example is NEXRCOMP.  The missing step is using the ldm-mcidas decoder
to convert the PNG compressed GINI into straight GINI.  This same process
is what is being done for the GOES imagery.  The ldm-mcidas example pqact.conf
entries show how to do this.

>Thanks a lot and have a good day!

Cheers,

Tom
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