MATLAB: 3D interpolation with interp3

3d interpolationinsufficient finite values to interpolateinterp3?

Hi,

I have three dimensional scattered data and want to interpolate my data on X-Y-Z space, but when I use 'spline' method or 'cubic' method matlab error occurs:

"Insufficient finite values to interpolate."

It says that I must have at least 4 points in each dimension and I have, then where is the problem?

My gridmesh is 21x21x21 and I have 4 sample points in X, Y and 21 sample points in Z for each X,Y.

Thanks,

Rafet

Best Answer

interp3 isn't meant for scattered data. You should be using scatteredInterpolant.

Related Solutions

MATLAB: Interpolation method (spline)

From the documentation:

'spline':

‘Spline interpolation using not-a-knot end conditions. The interpolated value at a query point is based on a cubic interpolation of the values at neighboring grid points in each respective dimension.’

It does not appear to be the same as 'cubic'. According to the documentation, 'cubic' is currently the same as 'pchip'.

MATLAB: Question with interp3

First error I saw was you were using lat/lon vectors that were 0.75 degree resolution where the wind data was 1 degree resolution. I instead read the lat/lon from the file to make sure the data matched the coordinates.

Next, the data's longitude range was 0:360 where the path longitude rage was -180:180. So I did the modulus of the longitude path data by 360 to fix that.

Lastly, you do not want to loop through data. Just do interp3 on complete dataset, much faster.

Try this:

addpath('nctoolbox-1.1.3');
load('matlab.mat')
setup_nctoolbox;
grib = ncgeodataset('2018_Jan.grib');
U_wind1 = grib.geovariable('10_metre_U_wind_component_surface');
U_wind = U_wind1.data(:, :, :);
U_wind = permute(U_wind,[2 3 1]);
time = grib.geovariable('time');
grib_time = double(time.data(:));
lat = grib.geovariable('lat');
grib_lat = double(lat.data(:));
lon = grib.geovariable('lon');
grib_lon = double(lon.data(:));
path_time_total_grib = path_time_total/6;
path_lon_value_grib = mod(path_lon_value,360);
U_wind_route = interp3( grib_lon,grib_lat,grib_time, U_wind,...
                path_lon_value_grib,path_lat_value,path_time_total_grib);

Best Answer

Related Solutions

MATLAB: Interpolation method (spline)

MATLAB: Question with interp3

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