[GRASSLIST:4139] RE: raster import help

[JGillette at rfmd.com]

Erase the first line:
   -90.000000   90.000000     .000000  360.000000     .250000     .250000

Add the following header to the file:

north: 90.125
south: -90.125
east: 360.125
west: -.125
rows: 721
cols: 1441

Import as x,y, then change the region setting to knock off
the top, bottom, left and right rows and columns. Export to ASCII,
add new header for lat/log and re-import.  This is necessary
because I don't think Grass will like a lat/log region with the
given parameters. (i.e. Lon<0 and >360, etc.)

This necessary because Grass dimensions its "squares" or "cells"
by the corners.

     0
     |
   +---+
   |   |
   | + |- +90  upper left cell has corner at -.125, +90.125 
   |   |       (based on 15min = .25deg spacing)
   +---+       (721 rows = 180 X 4 + 1, 1441 cols = 
                360 X 4 +1 )

I got the data imported into an X, Y location with the above header.

John

> -----Original Message-----
> From: Kevin Slover [mailto:Kevin.Slover at noaa.gov]
> Sent: Tuesday, July 23, 2002 11:32 AM
> To: grass-list
> Subject: [GRASSLIST:4129] raster import help
> 
> 
> I am working with data that uses the WGS84 geoid.  I am needed to
> convert this to MSL using, from what I have read, the EGM96 grid.  I
> have downloaded the grid from NIMA, and am trying to figure out how to
> import this into GRASS.
> 
> The grid is set up with 1st line being the header file, specifying N/S
> E/W and spacing.  Then the data.  Any thoughts, ideas on how 
> to get this
> in.  I tried r.in.gdal, but it says that the format cannot be
> recognized.
> 
> Also, just to be safe, am I going about this the right way??  I am
> thinking about creating the grid, then using r.mapcalc to compute MSL.
> Any thoughts on this??
> 
> Thanks...
> 
> 
> --
> LTJG Kevin Slover, NOAA
> GIS Specialist/Oceanographer
> NOAA/TPC/TSB/Storm Surge Unit
> 11691 SW 17th Street
> Miami FL  33165
> 
> W (305) 229-4456
> 
>