| Interpol. irregular grid to irregular grid [message #23662] |
Mon, 05 February 2001 18:23  |
deja_jlin
Messages: 12
Registered: February 2001
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Junior Member |
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howdy!
i'm trying to interpolate data from one irregular
2-D grid to another (different) irregular 2-D
grid:
- does IDL have any other built-in functions
besides MIN_CURVE_SURF that can do this?
- does anyone have any warnings regarding the
behavior of MIN_CURVE_SURF?
- has anyone implemented irregular-to-irregular
interpolations using other algorithms?
thanks!
best,
-Johnny Lin
-------------------------------------------
Johnny Lin
CIRES, University of Colorado
Work Phone: (303) 735-1636
Web: http://cires.colorado.edu/~johnny/
-------------------------------------------
Sent via Deja.com
http://www.deja.com/
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| Re: Interpol. irregular grid to irregular grid [message #23700 is a reply to message #23662] |
Thu, 08 February 2001 16:51  |
deja_jlin
Messages: 12
Registered: February 2001
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Junior Member |
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Craig and Mark,
thanks for your help! the grid turns out to be too large for
MIN_CURVE_SURF to be efficient, and the presence of missing
values in the dataset made MIN_CURVE_SURF troublesome, so i
ended up coding a near-neighbor scheme.
thanks again!
best,
-Johnny
-------------------------------------------
Johnny Lin
CIRES, University of Colorado
Work Phone: (303) 735-1636
-------------------------------------------
Sent via Deja.com
http://www.deja.com/
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| Re: Interpol. irregular grid to irregular grid [message #23714 is a reply to message #23662] |
Thu, 08 February 2001 12:32 |
Mark Hadfield
Messages: 783
Registered: May 1995
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Senior Member |
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<deja_jlin@my-deja.com> wrote in message news:95nn6i$25g$1@nnrp1.deja.com...
> howdy!
>
> i'm trying to interpolate data from one irregular
> 2-D grid to another (different) irregular 2-D
> grid:
>
> - does IDL have any other built-in functions
> besides MIN_CURVE_SURF that can do this?
Not that I'm aware of. It's a pity because there's no fundamental reason why
TRIGRID (for example) couldn't be modified to handled irregular output
grids.
> - does anyone have any warnings regarding the
> behavior of MIN_CURVE_SURF?
Yes! It's terribly slow when the input grid is of a significant size. For an
NxN input grid, the execution time of MIN_CURVE_SURF increases as approx.
N^3. This is because the alogorithm is non-local, i.e. every point in the
input grid affects every point in the output grid.
> - has anyone implemented irregular-to-irregular
> interpolations using other algorithms?
No but you could try calling TRIGRID repeatedly, once for every output
point...
---
Mark Hadfield
m.hadfield@niwa.cri.nz http://katipo.niwa.cri.nz/~hadfield
National Institute for Water and Atmospheric Research
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