| INTERPOLATION TECHNIQUES HELP [message #7435] |
Tue, 12 November 1996 00:00  |
![Marcos Portabella Arn[1] is currently offline](theme/default/images/xoffline.png.pagespeed.ic.XRkd1fkXye.png "Marcos Portabella Arn[1] is currently offline")
Marcos Portabella Arn[1]
Messages: 2
Registered: November 1996
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Junior Member |
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Hi,
I need some help about the idl interpolation functions. I have tried all of
them and I could not get any satisfactory result. I supose this is due to my
lack of knowledge about them and this is the reason I am writing to this
newsgroup list. I am using IDL version 4.0.1 (vms alpha). My problem is the
following:
I have three data vectors. The first two are X and Y position coordinates
(longitude and latitude) and the third one is the magnitude mesured at each
point (in my case, wind measurements). These points have not any order
(irregularly gridded points) . In order to make an interpolation of these
points in a regurlar grid (with a x and y spacing of half degree, for example)
I have tried all three idl functions that allow this type of interpolation. The
first one, the TRIGRID function, is very fast but the results are poor
(moreover, at the grid border, where it oftenly needs to extrapolate, the
results are incredibily wrong, even if I set the EXTRAPOLATE keyword). The
second one, the KRIG2D function, gives much better results but the major
problem is the execution time: the time increases exponentially with the number
of points. I do not know if changing the function parameters (A, CO, C1) may
reduce the execution time, but as far as I have tested with the idl help
examples I could no get any better result. The third and last one, the
MIN_CURVE_SURF function, has the same time restriction as the KRIG2D function.
I would like to know if there is any other interpolating function for
irregularly gridded points that gives better time results; or, if using more
addequatly the KRIG2D or MIN_CURVE_SURF functions I can get better time
results as well.
Thank you very much,
Marcos Portabella
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