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Re: Interpolating Irregular 2D Data [message #8606]

Wed, 26 March 1997 00:00

peter
Messages: 80
Registered: February 1994

Member

Achim Hein (hein@nv.et-inf.uni-siegen.de) wrote:
: Bijan Pesaran wrote:
: >
: > I have z=(x,y) data on a spiral and I want to sample it on a
: > grid for further manipulations, specifically kernel smoothing.
: >

: But I think the faster way is to interpolate the irregular data down to
: equidistant twodimensional axis - simultaneously, you smooth your data
: because of the interpolating.

Achim's suggestion is a good way to go -- the data on the spiral can be
placed onto a grid and smoothed at the same time by the procedure known
as gridding (essentially, convolving the non-rectilinear data with a
smoothing kernel onto the grid points). Very hard to do fast in IDL,
due to required (?) nested loops, since potentially every data point
lies at unique distances from its surrounding grid points, and thus
requires calculation of the interpolation weights; I've used a
call_external program to do it rapidly (and, in fact, to do spiral to
rectilinear conversion).

Peter

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		Re: Interpolating Irregular 2D Data By: peter on Wed, 26 March 1997 00:00
		Re: Interpolating Irregular 2D Data By: Achim Hein on Fri, 21 March 1997 00:00

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