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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

Senior Member

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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[Message index]

		Re: SMI/HDF format? By: d.poreh on Wed, 14 July 2010 03:09
		Re: SMI/HDF format? By: David Fanning on Tue, 13 July 2010 08:14
		Re: SMI/HDF format? By: Bruce Bowler on Tue, 13 July 2010 07:41
		Re: SMI/HDF format? By: d.poreh on Tue, 13 July 2010 06:18
		Re: SMI/HDF format? By: Bruce Bowler on Tue, 13 July 2010 05:08

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