20001110: higher res topo file

>From:  Robert Mullenax <address@hidden>
>Organization:  Universal Weather and Aviation
>Keywords:  200011101719.eAAHJaD06220 McIDAS-X topography imagery

Robert,

>At the MUG meeting I mentioned that we were interested (both NSBF
>and Universal) in obtaining a higher res topo file for the U.S.
>specifically one that when you zoom in on Texas and the Gulf Coast
>the coastline does not become blocky.

Yes, I remember.

>You said that you had a file
>that needed to be converted to an area file and could provide info on
>obtaining the file and some info on how to convert it.

You can grab the file, USA30.Z from the data/topography directory of
the passworded McIDAS FTP account on our FTP server ftp.unidata.ucar.edu
(you should still have the access information).  At the same time, grab
the file USA30.info.  This file contains "shape" information for the
data in USA30 (upper left LAT,LON; lower right LAT,LON; # lines & elements;
data range for the elevation data; spacing in degrees between pixels
in the horizontal (along a line) and vertical (along an element column).

>When you get a chance could you send me that info?

The process of turning this into an AREA file is as follows:

o FTP the file to your McIDAS-X working directory or to a directory in
  your MCPATH (or setup a file REDIRECTion); make sure to FTP in binary
  mode!!!!!
o uncompress the file USA30.Z
o read USA30.info
o read the data into an AREA:

MAKEAREA USA30 1234 3240 8160 0 2 -85 4328

o navigate the image:

MAKNAV 1234 RECT=0 51 0 128 0.0083333 0.0083333

I just did the MAKEAREA and MAKNAV steps above and was pleased
with the results.

It just struck me that you may not have the Unidata-supplied MAKEAREA
routine in your SSEC McIDAS distribution.  You can either grab the
source from NSBF (makearea.pgm) and add the build to your distribution
of McIDAS, or you can grab it from the data/topography/src directory.

Since you are interested in higher resolution topography over a smaller
spatial domain, you may want to modify MAKEAREA to support extraction
of sub spatial domains (MAKEAREA already supports the mapping of
differing ranges of elevations (through pixel values), so you shouldn't
have to muck with that) If you do make the sub spatial domain
extraction, how about contributing the mods back for the cause :-)

>It was good to see you at the MUG.  Maybe I'll see you there next year.

OK.  Let me know if you have any problems with the USA30 topography
dataset.

>Robert Mullenax
>Universal Weather and Aviation (a McIDAS Users Group member)
>Assistant Weather System Administrator

Tom

>From address@hidden Mon Nov 13 11:56:23 2000
>Subject: Re: 20001110: higher res topo file

Thanks a bunch Tom!

I'll make that this afternoon.

Robert