How to interpolate in 3d?

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Shubham Mohan Tatpalliwar
Shubham Mohan Tatpalliwar on 18 Feb 2019
Commented: Akira Agata on 21 Feb 2019
I have a matrix in 100 distane and 10 distance which i want to interpolate to 1
but as it is a matrix i want to interpolate in 3D
I have tried it interpolating in 2D and getting some irregularities in the which can be seen in attached picture
The 2D code is as follows
[num] = xlsread('Mappe2.xlsx') ;
n = 860;
num1=num(2:87,2:26)';
B = interp1(1:size(num1, 2), num1.', linspace(1, size(num1, 2), n));
n = 250;
B1 = interp1(1:size(B, 2), B.', linspace(1, size(B, 2), n));
surf(1:860,1:250,B1,'edgecolor','none');
How to code further to avoid these irregularities?
I have also attached the Excel file feom the code
forum.PNG

Accepted Answer

Akira Agata
Akira Agata on 19 Feb 2019
You can use scatteredInterpolant to do this task. The following is an example.
% Read data file
Data = xlsread('Mappe2.xlsx') ;
% Adjust data to grid data format
x = Data(1,2:end);
y = Data(2:end,1);
[xGrid,yGrid] = meshgrid(x,y);
zGrid = Data(2:end,2:end);
% Apply scatteredInterpolant function
idx = isnan(zGrid(:));
F = scatteredInterpolant(xGrid(~idx),yGrid(~idx),zGrid(~idx),...
'linear','linear');
% Interpolation (linear) and Extrapolation (linear)
zGridInterp = F(xGrid,yGrid);
% Show the result
figure
surf(xGrid,yGrid,zGridInterp,...
'EdgeColor', 'none',...
'FaceColor', 'interp')
view(2)
colorbar
surf.png
  4 Comments
Shubham Mohan Tatpalliwar
Shubham Mohan Tatpalliwar on 21 Feb 2019
no i want x=1:1:8500 and y=1:1:240
Akira Agata
Akira Agata on 21 Feb 2019
OK, that's a piece of cake.
I have slightly modified to do that. I hope this will be some help!
% Read data file
Data = xlsread('Mappe2.xlsx');
Data = Data';
% Adjust data to grid data format
x = Data(1,2:end);
y = Data(2:end,1);
[xGrid, yGrid] = meshgrid(x,y);
zGrid = Data(2:end,2:end);
% Apply scatteredInterpolant function
idx = isnan(zGrid(:));
F = scatteredInterpolant(xGrid(~idx),yGrid(~idx),zGrid(~idx),...
'linear','linear');
% New grid
[xGrid2, yGrid2] = meshgrid(1:8500,1:240);
% Interpolation (linear) and Extrapolation (linear)
zGridInterp = F(xGrid2,yGrid2);
% Show the result
figure
surf(xGrid2,yGrid2,zGridInterp,...
'EdgeColor', 'none',...
'FaceColor', 'interp')
view(2)
colorbar
surf2.png

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