Plotting Lines and Points in 3D

2024 5 21
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I need to learn how to plot lines and points in 3D. Can someone please provide an example in Matlab? Thank you.

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Voss
Voss 2024-5-21
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A = [1 -3 7];
B = [0 2 -6];
C = [0.5 -1 5];
% plot a line from A to B
v = [A; B];
plot3(v(:,1),v(:,2),v(:,3))
box on
grid on
xlabel('x')
ylabel('y')
zlabel('z')
% plot the point C
hold on
plot3(C(1),C(2),C(3),'o')

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DJ V
DJ V 2024-5-21
编辑：Voss 2024-5-21
Thank you for troubling to answer: I come up with the following trying to create a drawing, but two of the lines aren't being shown. The ones that go to -1 on the Y axis. Can this be fixed to include the -1 on the Y axis? Is there a way to control the magnitude of the box that is being turned on? Is there a way to control the dimensions of the box that is turned on? Thanks.
A1 = [0 0 0];
A2 = [1 1 2];
A3 = [-1 1 2];
A4 = [1 -1 2];
A5 = [-1 -1 2];
% plot a line from A1 to AN
v = [A1; A2];
plot3(v(:,1),v(:,2),v(:,3))
box on
hold on
v = [A1; A3];
plot3(v(:,1),v(:,2),v(:,3))
hold on
v = [A1, A4];
plot3(v(:,1),v(:,2),v(:,3))
hold on
v = [A1, A5];
plot3(v(:,1),v(:,2),v(:,3))
hold on
box on
grid on
Voss
Voss 2024-5-21
Ran in:
Ran in:
You're welcome!
The problem with the plots involving A4 and A5 is that you're horizontally concatenating instead of vertically concatenating, which makes v 1x6 instead of 2x3. When v is 1x6, doing plot3(v(:,1),v(:,2),v(:,3)) plots a single point instead of two points with a line in between.
A1 = [0 0 0];
A2 = [1 1 2];
A3 = [-1 1 2];
A4 = [1 -1 2];
A5 = [-1 -1 2];
% plot a line from A1 to AN
v = [A1; A2];
plot3(v(:,1),v(:,2),v(:,3))
hold on
v = [A1; A3];
plot3(v(:,1),v(:,2),v(:,3))
v = [A1; A4];
% ^ semicolon (not comma)
plot3(v(:,1),v(:,2),v(:,3))
v = [A1; A5];
% ^ semicolon (not comma)
plot3(v(:,1),v(:,2),v(:,3))
box on
grid on
You can control the axes limits (and thus the box around the axes) using xlim, ylim, and zlim, e.g.:
ylim([-1 2])
DJ V
DJ V 2024-5-21
Thank you very much!
Voss
Voss 2024-5-21
You're welcome! Any questions, let me know. Otherwise, please "Accept" this answer. Thanks!
DJ V
DJ V 2024-5-21
Is there any command I can give to get MATLAB to draw this thing to scale? Thank you.
DJ V
DJ V 2024-5-21
The man with all the answers!

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