Rotating data using griddata

Question

ran 2023-9-24

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/2025067-rotating-data-using-griddata

评论： Matt J 2023-9-25

Tdata5000.mat

I have a tmperature flow data abouve wall with a slop. I want to smooth the data on the wall so i rotated the data using griddata(). now i want to retern to the original palne so i tray the same thing but i get matrix of NaN. do griddata() work with matrixs? any way to fix it? in my code xn yn and Tn are the original data.

load Tdata5000

theta = -atan2(0.002, 0.005 ); % in degrees

% Calculate the rotated x and y coordinates element-wise

rotated_x = xn.* cos(theta) - yn.* sin(theta);

rotated_y = xn.* sin(theta) + yn.* cos(theta);

num_points = 1000; % Adjust this number as needed

uniqe_x = linspace(min(rotated_x(:)), max(rotated_x(:)), num_points);

uniqe_y = linspace(min(rotated_y(:)), max(rotated_y(:)), num_points);

[X, Y] = meshgrid(uniqe_x, uniqe_y);

% Interpolate the temperature data onto the grid

rotated_T = griddata(rotated_x, rotated_y, Tn, X, Y);

rotated_T = smoothdata(rotated_T,2,'movmean',35);

% Reverse the rotation by using the negative angle

reverse_theta = -theta;

% Calculate the rotated x and y coordinates element-wise

original_x = X .* cos(reverse_theta) - Y .* sin(reverse_theta);

original_y = X .* sin(reverse_theta) + Y .* cos(reverse_theta);

% Interpolate the rotated and smoothed data onto the original grid

original_T = griddata(X, Y, rotated_T, original_x, original_y,'cubic');

contourf(original_x, original_x, original_T)

Warning: Contour not rendered for non-finite ZData

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Answer 1

Matt J 2023-9-24

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https://ww2.mathworks.cn/matlabcentral/answers/2025067-rotating-data-using-griddata#answer_1317052

You should probably just use imrotate with the loose option flag.

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ran 2023-9-25

编辑：ran 2023-9-25

i use 'cubic' intarpulation in 'griddata()' yes. when i use imrotate the adges of my data get wired, some of my data delleted when i rotate the data in the first place then when i tray to get back i ge exsta data where my data was befor how i fix that????? but i think using imrotate willl be much easer aproch then what i do now.

another problem i have with it that i cant use it to flip the image then flip it back beacuse for some reason it crate the problem again, so all i want to do it to flip it from the 'griddata()' back to the original results without any missing data