| Re: interact with iimage from the command line? [message #60439] |
Wed, 21 May 2008 20:29  |
KRDean
Messages: 69
Registered: July 2006
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Member |
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On May 21, 9:54 am, David Fanning <n...@dfanning.com> wrote:
> kBob writes:
>> I deal with imagery that can total upto 50Gb and image objects allow
>> me to navigate around these large files on a desktop Windows XP with
>> only a 1 Gb RAM. The secret is not to read the whole image, but to
>> pick at it. Pull out the chunks you need.
>
> OK, now this has got my attention.
>
> I don't suppose you have a nice little example of this,
> do you? For the life of me, I can't see how to create
> the image object so that the data is not also loaded.
> Can you please enlighten us further?
>
> Cheers,
>
> David
>
> --
> David Fanning, Ph.D.
> Fanning Software Consulting, Inc.
> Coyote's Guide to IDL Programming:http://www.dfanning.com/
> Sepore ma de ni thui. ("Perhaps thou speakest truth.")
I found out how to do this from Mark Piper at ITTVIS in his Advance
IDL course. The code is very similiar to what Galloy presents at his
site. You can find the ITTVIS version on their ftp site ...
ftp://ftp.ittvis.com/training/IDL_advanced/
You'll find the code in the zip file under the tiler directory.
Just like Galloy's, it is a GUI example using JPEG2000 as input. It
was a great way to learn how to use IDL Objects.
IDL's help has a nice discussion too, "Adding Tiling to Your
Application".
Not knowing the source of Adam's data, I use GeoTIFF. You can use
ENVI's input routines, but IDL's READ_TIFF can read a rectangle
region, so you are not limited to just JPEG2000.
So to be more enlighting, take the JPEG2000 out and input the IDL's
READ_TIFF with its SUB_RECT keyword.
However, first use the IDLgrImage to set up the "tiles". Instead of
the JPEG2000 tiles, the tiles are the dimensions of the input files,
for example, the 100x10000 arrays. No need to read in the data. Let
the OBJECT GRAPHICS determine what you need to pull.
Use the VIEWPLANE_RECT in IDLgrView to input your full sample data
location.
Let the QueryRequiredTiles in IDLgrWindow determine what file you
need to open and the rectangle area you need to pull with READ_TIFF,
SUB_RECT.
Hopefully, this will help Adam...
Kelly Dean
Fort Collins, CO
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