[SciPy-user] [Fwd: 3D interpolation over irregular data]
Thu Jul 31 06:12:10 CDT 2008
Thanks for your comments. Knowing that other people split the
interpolation into regions is useful. I'll be attempting an approach
similar to that you suggested; splitting the domain, not around each
desired point but into regions containing sets of points.
I didn't expect the effect you mention about accuracy being related to
the number of points. Looks like I need to read up on the theory....
José María García Pérez wrote:
> From my experience working with RBF, they work pretty well even when you
> use few points for the interpolation. They track non linear behavior
> very well.
> I have worked with RBF with very big FEM models (200000-500000 grid
> points) and with more than 3D (in other disciplines), but I don't take
> all the points at the same. What I would do is to use for example the
> 100 nearest points to the geometric point where you want to interpolate
> (probably with 10 would be enough). That's something you can try: test
> using 10, 20, 50, 100 points, and you will see that the difference is
> small pretty soon, and for sure smaller that the error you may expect
> from a CFD simulation.
> Hope this tip helps!
> José M.
> 2008/7/31 mark starnes <firstname.lastname@example.org
> Hi again, Stéfan.
> Is Robert Kern's package limited to two-dimensional data? I've had a
> look and can't see any three-dimensional options.
> Best regards,
> Stéfan van der Walt wrote:
> > Hi Mark
> > 2008/7/30 mark starnes <email@example.com
> >> Hi everyone,
> >> I've looked through the list here and in Numpy-users, and checked the
> >> 'net but can't find an answer to this problem (with luck, I've missed
> >> something obvious!).
> >> I've an array of velocities at 80,000 points, irregularly spaced
> (from a
> >> CFD analysis). I'd like to generate the interpolated velocity at any
> >> position in the domain, to map the data to an acoustics analysis on a
> >> different mesh.
> >> I tried a least squares approach but the errors are too large using
> >> polynomials and trigonometric functions. My conclusion is that I
> need a
> >> nearest-neighbour type interpolation routine.
> > Also take a look at
> > Robert Kern's delaunay package does natural neighbour
> interpolation, IIRC.
> > Regards
> > Stéfan
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