| matching irregular data sets [message #27786] |
Wed, 07 November 2001 15:45  |
Steve W. Nesbitt
Messages: 1
Registered: November 2001
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Junior Member |
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Howdy,
This may or may not be a dumb question. I am working on matching two
irregularly-spaced remote sensing data sets, specifically doing a
nearest-neighbor or bilinear interpolation of one data set to another.
I have written a routine to do this, but it is painfully slow since the
arrays I'm matching are lat/lon grids [400,3000]. I have searched the
manual ad nauseum! for an IDL canned routine to do this, but they seem
to require that the output grids be regularly spaced. I would like the
output to be gridded to the second irregular grid, and it would be nice
if it would return the indices of the original grid in the output. Let
me know if one of you IDL gurus can help me out on this one.
Many thanks,
-Steve
____________________________________________________________ ____________
Steve Nesbitt 135 S 1460 E WBB Rm. 806C
Ph.D. Research Assistant Salt Lake City, UT 84112-0110
Tropical Convection Research Group Phone: 801-581-3458
University of Utah-Department of Meteorology Fax: 801-585-3681
http://www.met.utah.edu/zipser/nesbitt
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| Re: matching irregular data sets [message #27908 is a reply to message #27786] |
Thu, 08 November 2001 17:25  |
air_jlin
Messages: 22
Registered: July 2001
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Junior Member |
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hi Steve,
i'm not an idl guru, but my experience with interpolating large fields
is that it's just plain slow (i've tried a couple methods).
if you're interested in how i did my near neighbor, you can see it at:
http://www.johnny-lin.com/lib.html#atmos
it's called NN_INTERP, and isn't the prettiest, but it seems to work.
the main slow down is that it calculates the distances between *all*
possible location pairs, since i wanted the procedure to be able to
accomodate irregular input and output grids. if you have a timeseries
of fixed grids, you can speed things up tremendously by precalculating
the distances (the procedure has that option in it).
hope this helps!
best,
-Johnny
-------------------------------------------
Johnny Lin
CIRES, University of Colorado
Work Phone: (303) 735-1636
Web: http://cires.colorado.edu/~johnny/
-------------------------------------------
"Steve W. Nesbitt" <snesbitt@met.utah.edu> wrote in message
news:<3BE9C7B3.DE76D102@met.utah.edu>...
> Howdy,
>
> This may or may not be a dumb question. I am working on matching two
> irregularly-spaced remote sensing data sets, specifically doing a
> nearest-neighbor or bilinear interpolation of one data set to another.
> I have written a routine to do this, but it is painfully slow since the
> arrays I'm matching are lat/lon grids [400,3000]. I have searched the
> manual ad nauseum! for an IDL canned routine to do this, but they seem
> to require that the output grids be regularly spaced. I would like the
> output to be gridded to the second irregular grid, and it would be nice
> if it would return the indices of the original grid in the output. Let
> me know if one of you IDL gurus can help me out on this one.
>
> Many thanks,
> -Steve
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| Re: matching irregular data sets [message #27920 is a reply to message #27786] |
Thu, 08 November 2001 12:39 |
Pavel A. Romashkin
Messages: 531
Registered: November 2000
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Senior Member |
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Is BILINEAR(P, X, Y) of any use? Or is it the one that is so slow?
Pavel
"Steve W. Nesbitt" wrote:
>
> Howdy,
>
> This may or may not be a dumb question. I am working on matching two
> irregularly-spaced remote sensing data sets, specifically doing a
> nearest-neighbor or bilinear interpolation of one data set to another.
> I have written a routine to do this, but it is painfully slow since the
> arrays I'm matching are lat/lon grids [400,3000]. I have searched the
> manual ad nauseum! for an IDL canned routine to do this, but they seem
> to require that the output grids be regularly spaced. I would like the
> output to be gridded to the second irregular grid, and it would be nice
> if it would return the indices of the original grid in the output. Let
> me know if one of you IDL gurus can help me out on this one.
>
> Many thanks,
> -Stevee
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