| Re: Display and Navigate Image in IDL 8.2 [message #81358 is a reply to message #81350] |
Tue, 11 September 2012 09:12   |
lecacheux.alain
Messages: 325
Registered: January 2008
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Senior Member |
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Le mardi 11 septembre 2012 17:28:39 UTC+2, David Fanning a écrit :
>
> Just curious, but what do you think they mean by OVERPLOT?
> Clearly, it's not what I mean, but it must mean something. :-)
>
OVERPLOT in NG is quite different from OPLOT in DG ! Basically, scales of first and second plots are BOTH adjusted to fit in the window. This can be quite surprising... Documentation does not help much.
To keep the first plot unchanged, you must do something like:
p = plot(...)
q = plot(..., /OVERPLOT, XRANGE=p.XRANGE, YRANGE=p.YRANGE)
In order to simply superimpose two plots (whatever their respective scaling are), CURRENT is enough (it plays nearly the same role as NOERASE in DG).
>> 3) where your values "LONGITUDE_MIN=-105.18, LATITUDE_MIN=40.54"
>> are coming from ? Please refer to my previous (saturday) post,
>> for the recovery of the right (?) values.
>
> Well, I'm not sure about "right (?)" values. I use them
> so I can compare the results with the correct Coyote
> Graphics display. I use them to locate the first drawn
> grid line in the lat and lon directions. They certainly
> seem to be doing the job for me.
I would prefer to get them from available image metadata. In the case of GoogleMaps, we can just speculate, but in case of other more documented satellite image (for which you know exactly the used projection and boundary values) you should be able to check everything precisely.
Cheers,
Alain.
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