Iporting different kinds of raster layers

[Stephan Eickschen]

Hi everybody-

I need a little bit assistance in projection stuff, importing
raster files etc.

What I have:
============

Different kind of datasets:
1) passive microwave, gridded on a regular grid as shown in the figure.
	(it is the SSM/I - NSIDC grid)

2) optical and infrared raw data (AVHRR)
3) gtopo30 topography

What I did:
===========

Set up a GRASS5 mapset which fits the SSM/I grid; it is an x-y mapset.

What I want:
============

Import datatype 2) and 3) into this mapset. :)
In case of the AVHRR data I am able to choose from a varity of
projections
in which I want to have the raw data after some basic processing, but
there
are "only" geographic ones (like polar stereographic, which I thought it
would be most suitable, since the SSM/I grid is based on a polar
stereographic grid - unfortunatly, I am not able to get a dataset with
the
same edges as the mapset - it is always of the shape of trapecoid (sp?))
If I know how to import the gtopo30 into my mapset I will be able to
manage
the AVHRR data since gtopo30 is in "Equidistant Cylindrical" - I can get
the
AVHRR data into a similar grid...

lat = -39.23 deg              lat = -39.23 deg
lon = 317.76 deg              lon =  42.24 deg
       +----------- 4350 -----------+
       |                            |
       |                            |
       |                            |
       |                            |
       |                            |
    -3950             o           3950
       |           Southpole        |
       |                            |
       |                            |
       |                            |
       |                            |
       |                            |
       +---------- -3950 -----------+
lat = -41.45 deg              lat = -41.45 deg
lon = 225.00 deg              lon = 135.00 deg

dx = 12.5
dy = 12.5

(A (slightly) better image is available at
	http://www-nsidc.colorado.edu/NASA/GUIDE/SSMI/gridmap.JPG
on the right side - even though the anotations of the upper right and
the
lower left corner have to be changed...)

What I don't know:
==================

is how to "jump" between / fit / take account to the different types of
projections (how ever you want to call it)...

Any suggestions will be highly appriciated!!!
-- 
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Stephan Eickschen                     Tel. : +49 (0)251 83-34704
Westfaelische Wilhelms-Universitaet   Fax. : +49 (0)251 83-36100
Institute for Geophysics
Research Unit of Physical Glaciology  email: eicksch at uni-muenster.de
Corrensstrasse 24
48149 Muenster
Germany
		http://earth.uni-muenster.de/~eicksch/
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