# rotate the coordinates plotted with plot3 without changing the axes

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Alberto Acri on 20 Dec 2022
Commented: Alberto Acri on 20 Dec 2022
Hi. I need to rotate the plotted curves (3D figure on the left) by 180° as shown in the figure on the right. Is there any efficient method?
Attached is the code.

Karim on 20 Dec 2022
Hi, in the code below I added some comments to demonstrate how you can rotate the curve.
binaryImage = imageArray;
binaryImage = ~binaryImage;
M1 = function_verification_code(binaryImage);
z = 100;
figure
current_z = z * ones(size(M1, 1), 1);
plot3(M1(:, 2), M1(:, 1), current_z, 'b.')
grid on
xlabel('X');ylabel('Y');zlabel('Z');
view([15 50 30])
title("Original Curve - Figure A")
% adjust the x and x vectors before we apply the rotation
M_rot = M1(:,[2 1]);
% find the mean of the curve in the x-y axis, we will use this point as rotation center
P0 = mean(M_rot,1);
% shift grid to the center for the rotation
M_rot = M_rot - repmat(P0,size(M1, 1),1);
% set up the rotation matrix about the z-axis
Rot = @(x) [cosd(x) -sind(x); sind(x) cosd(x)];
% rotate the shifted grid with 180 degrees
M_rot = (Rot(180) * M_rot')';
% shift the curve back to its own centroid
M_rot = M_rot + repmat(P0,size(M1, 1),1);
figure
current_z = z * ones(size(M_rot, 1), 1);
plot3(M_rot(:,1), M_rot(:,2), current_z, 'b.')
grid on
xlabel('X');ylabel('Y');zlabel('Z');
view([15 50 30])
title("Rotated Curve - Figure A")
##### 3 CommentsShow 1 older commentHide 1 older comment
Star Strider on 20 Dec 2022
The rotate function can rotate multiple plots at once, and keep their relative positions unchanged. They can slso be rotated individually.
t = linspace(0, 1, 500);
r = 1;
x = r*cos(2*pi*t) + [0; 0; 0];
y = r*sin(2*pi*t) + [0; 0; 0];
z = ones(size(t)) + [0; 1; 2];
figure
hold on
for k = 1:size(x,1)
hp3(k) = plot3(x(k,:), y(k,:), z(k,:)); % Three Separate 3D Plots
end
hold off
grid on
axis('equal')
view(60,30)
xlabel('X')
ylabel('Y')
zlabel('Z')
title('Original')
figure
hold on
for k = 1:size(x,1)
hp3(k) = plot3(x(k,:), y(k,:), z(k,:)); % Three Separate 3D Plots
end
hold off
grid on
axis('equal')
view(60,30)
xlabel('X')
ylabel('Y')
zlabel('Z')
rotate(hp3, [1 2 0], 45) % Call 'rotate'
title('Rotated Original')
Make appropriate changes to work with your data.
Thanking @Karim again for solving the .mat file load problem using the online Run feature, so not posting this as a separate Answer.
.
Alberto Acri on 20 Dec 2022
I thank you both.
I modified that line as:
P0 = [A/2, B/2]; % where A and B are the size of the image on x and on y.
I will also keep an eye on your solution @Star Strider in case I need it in the future.

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