| Re: Map_set limits / position [message #10465] |
Mon, 01 December 1997 00:00 |
Martin Schultz
Messages: 515
Registered: August 1997
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Senior Member |
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This is a multi-part message in MIME format.
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David Fanning wrote:
>
> Hi Folks,
>
> I have to admit that I am confused about recent postings
> from St�phane Erard and Martin Schultz, who complain about
> having to fiddle with the Position parameters to get a
> Map_Set command to fit the proper Limits around an image.
>
[...]
David (and others who are still interested),
please find attached a sample image of the GEOS 9 satellite which is
centered at -135 W longitude and over the equator and orbits in a
distance of about 7 earth radii (those are the parameters I used in my
image_map routine posted earlier today).
I downloaded your TVIMAHGE program (it certainly *is* very nice), and
tried it in the manner you suggested. Luckily (o r unluckily whichever
standpoint you take), the 2% difference noted by Stephane remains (see
the attached sample program newsat.pro). The nice thing about the
satellite image is that it already contains continent boundaries, so the
task is to match these exactly with IDL's. Of course, I could still be
somewhat in error about my estimates of the satellite's position, but I
played around more than half a day with this and finally found that I
have to enlarge the map by 2% in order to match the two. When i did
this, I was still working with IDL 4.0, but we upgraded recently, and
the same problem remains as you can see if you try this out.
BTW: the color codings are from my myct color scheme, you should display
the image with color table 0.
Regards,
Martin.
------------------------------------------------------------ -------
Dr. Martin Schultz
Department for Earth&Planetary Sciences, Harvard University
186 Pierce Hall, 29 Oxford St., Cambridge, MA-02138, USA
phone: (617)-496-8318
fax : (617)-495-4551
e-mail: mgs@io.harvard.edu
IDL-homepage: http://www-as.harvard.edu/people/staff/mgs/idl/
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Content-Type: image/jpeg; name="249_2100ful1.jpg"
Content-Transfer-Encoding: base64
Content-Disposition: inline; filename="249_2100ful1.jpg"
<encoded_portion_removed>
2Q==
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Content-Type: text/plain; charset=us-ascii; name="newsat.pro"
Content-Transfer-Encoding: 7bit
Content-Disposition: inline; filename="newsat.pro"
pro newsat,image
; read_jpeg,'~/download/gte/249_2100ful1.jpg',image
; image = image(93:1041,23:927)
thispos = [0.1,0.1,0.9,0.9]
map_set,0,-135,/satellite,sat_p=[7,0,0],position=thispos
tvimage,image,/keep_ap,pos=thispos
map_grid,color=2
map_continents,color=7
return
end
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