interpolate 3 dimensional arrays (in time and space)

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wave_buoys 2018-8-28

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评论： wave_buoys 2018-8-29

Hi all,

I have 3D matrix 180x90x120 which is equal to lonxlatxtime. In space, the data has 1 degree resolution (e.g. longitude ranges from 1 to 180), while the time interval is 3 hours (e.g. 3h, 6h, 9h.....).

Now I want to interpolate data to get a finer resolution of 0.5 degree and with 1-hour interval, so the new matrix would be 360x180x360.

Could you please help?

Thanks

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Matt J 2018-8-28

编辑：Matt J 2018-8-28

No, do not use griddata for this. KL's suggestion of griddedInterpolant was appropriate. See also my second answer.

Matt J 2018-8-28

编辑：Matt J 2018-8-28

Now I want to interpolate data to get a finer resolution of 0.5 degree and with 1-hour interval, so the new matrix would be 360x180x360.

Those will not be the new dimensions. If you sample from 1 to 180 at intervals of 0.5, you will obtain 359 points, not 360. Similarly for the other dimensions.

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Answer 1

Matt J 2018-8-28

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编辑：Matt J 2018-8-28

在 MATLAB Online 中打开

 F=griddedInterpolant(yourData);
  qlon=(1:.5:180);
  qlat=(1:.5:90);
  qtime=(1:1/3:120);
 newData=F({qlon,qlat,qtime});

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wave_buoys 2018-8-29

THIS WORKS FOR ME!!!!!!!! THANKS MATT

wave_buoys 2018-8-29

在 MATLAB Online 中打开

Dear Matt J,

Sorry. It works but the outcomes are not as I expected. Particularly the new results look weird. Perhaps I also misunderstood about the input matrix format. To be corrected, the 3D matrices I mentioned, for instance, 180x90x120 contains 120 2D arrays size (180x90) for monthly wind speeds in Longitude and Latitude direction. These 120 matrices correspond to a 1D time matrix (which is separated): 0h 6h 12h 18h.....720h..

So when I use:

v = winddata % (size: 180x90x120)
F= griddedInterpolant(v)
qlon=(1:.5:180)
qlat=(1:.5:90);
qtime=(1:1/3:120);
newwinddata=F({qlon,qlat,qtime});

it does not work properly because time does not present in griddedInterpolant(v).

May you help more? Thanks

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Answer 2

Matt J 2018-8-28

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编辑：Matt J 2018-8-28

在 MATLAB Online 中打开

You could download IMRESIZEN, and then do things like,

>> A=rand(180,90,120); B=imresizen(A,[2,2,3]); whos B
Name   Size            Kilobytes     Class    Attributes
B      360x180x360        182250     double