| Re: SMI/HDF format? [message #71671] |
Wed, 14 July 2010 03:09 |
d.poreh
Messages: 406
Registered: October 2007
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Senior Member |
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On Jul 13, 8:14 am, David Fanning <n...@dfanning.com> wrote:
> Bruce Bowler writes:
>> If I were you, I'd display the image (perhaps subsampled) and see where
>> the continents appear and make a decision based on that (strangely,
>> sometimes the image appears "upside down").
>
> In IDL, projected images are *always* upside down. :-)
>
> Cheers,
>
> David
>
> --
> David Fanning, Ph.D.
> Fanning Software Consulting, Inc.
> Coyote's Guide to IDL Programming:http://www.dfanning.com/
> Sepore ma de ni thue. ("Perhaps thos speakest truth.")
Thanks Guys!
Cheeers
Dave
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| Re: SMI/HDF format? [message #71684 is a reply to message #71671] |
Tue, 13 July 2010 08:14  |
David Fanning
Messages: 11724
Registered: August 2001
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Senior Member |
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Bruce Bowler writes:
> If I were you, I'd display the image (perhaps subsampled) and see where
> the continents appear and make a decision based on that (strangely,
> sometimes the image appears "upside down").
In IDL, projected images are *always* upside down. :-)
Cheers,
David
--
David Fanning, Ph.D.
Fanning Software Consulting, Inc.
Coyote's Guide to IDL Programming: http://www.dfanning.com/
Sepore ma de ni thue. ("Perhaps thos speakest truth.")
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| Re: SMI/HDF format? [message #71686 is a reply to message #71684] |
Tue, 13 July 2010 07:41 |
Bruce Bowler
Messages: 128
Registered: September 1998
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Senior Member |
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On Tue, 13 Jul 2010 06:18:48 -0700, Dave Poreh set fingers to keyboard and
typed:
> On Jul 13, 5:08 am, Bruce Bowler <bbow...@bigelow.org> wrote:
>> On Tue, 13 Jul 2010 04:13:27 -0700, Dave Poreh set fingers to keyboard
>> and typed:
>>
>>> Folks
>>> Does anyone know what is SMI/HDF format? I have some images and I can
>>> read by nCDF_Browser, file, but when I open it is giving me an
>>> array(8640,4320) without any coordinates. But what I want is having
>>> data in (lon,lat,C) format. If this is for entire glob, how can I do
>>> this? Any help?
>>> Cheers
>>
>> SMI = "Standard Mapped Image" (I think) and there are 8640 pixels at
>> the equator and 4320 between the poles. From that, there are 8640/360
>> pixels per degree (at the equator) or 0.041667 degrees per pixel. From
>> that you can construct a grid which corresponds to the lat and lon at
>> the center of each pixel.
>>
>> Bruce
>
> How could I know where is the 0 0 00 apparently it is not the left most
> pixel. I mean should I have start from -180 for lon (-90 for lat)?
> Cheers
In the data I'm familiar with in this format, lat=0, lon=0 is the center
of the array and the lower left corner is -90+(0.041667/2), -18
+(0.041667/2) (needed to have the pixels "symetric")
If I were you, I'd display the image (perhaps subsampled) and see where
the continents appear and make a decision based on that (strangely,
sometimes the image appears "upside down").
Bruce
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| Re: SMI/HDF format? [message #71688 is a reply to message #71686] |
Tue, 13 July 2010 06:18 |
d.poreh
Messages: 406
Registered: October 2007
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Senior Member |
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On Jul 13, 5:08 am, Bruce Bowler <bbow...@bigelow.org> wrote:
> On Tue, 13 Jul 2010 04:13:27 -0700, Dave Poreh set fingers to keyboard and
> typed:
>
>> Folks
>> Does anyone know what is SMI/HDF format? I have some images and I can
>> read by nCDF_Browser, file, but when I open it is giving me an
>> array(8640,4320) without any coordinates. But what I want is having data
>> in (lon,lat,C) format. If this is for entire glob, how can I do this?
>> Any help?
>> Cheers
>
> SMI = "Standard Mapped Image" (I think) and there are 8640 pixels at the
> equator and 4320 between the poles. From that, there are 8640/360 pixels
> per degree (at the equator) or 0.041667 degrees per pixel. From that you
> can construct a grid which corresponds to the lat and lon at the center
> of each pixel.
>
> Bruce
How could I know where is the 0 0 00 apparently it is not the left
most pixel. I mean should I have start from -180 for lon (-90 for
lat)?
Cheers
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| Re: SMI/HDF format? [message #71689 is a reply to message #71688] |
Tue, 13 July 2010 05:08 |
Bruce Bowler
Messages: 128
Registered: September 1998
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Senior Member |
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On Tue, 13 Jul 2010 04:13:27 -0700, Dave Poreh set fingers to keyboard and
typed:
> Folks
> Does anyone know what is SMI/HDF format? I have some images and I can
> read by nCDF_Browser, file, but when I open it is giving me an
> array(8640,4320) without any coordinates. But what I want is having data
> in (lon,lat,C) format. If this is for entire glob, how can I do this?
> Any help?
> Cheers
SMI = "Standard Mapped Image" (I think) and there are 8640 pixels at the
equator and 4320 between the poles. From that, there are 8640/360 pixels
per degree (at the equator) or 0.041667 degrees per pixel. From that you
can construct a grid which corresponds to the lat and lon at the center
of each pixel.
Bruce
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