Plot a unit vector in MATLAB, given its starting point and the orientation about 3 axes

I have a point [x y z] and the Euler orientation angles [r p y]. How can I plot a unit vector in MATLAB starting from [x y z] in the orientation of [r p y] ?

[Adam Danz]

If you're using a polarplot() you simply supply the angle and magnitude

polarplot(theta, rho)  %theta is in radians

If you're plotting that in cartesian coordinates, convert (theta,rho) to (x,y) using,

[x,y] = pol2cart(theta,rho)

Check out the documentation for pol2cart for input requirements.

[crisdeodates]

Thanks Adam, but my requirement is to use Euler angles to plot a unit vector starting at the specified point. And my goal is to get the plot in 3D.

[Adam Danz]

Ah, right. Then sph2cart() would be more useful

[x,y,z] = sph2cart(azimuth,elevation,r)

or rotm = eul2rotm(eul) and eul = rotm2eul(rotm)

This link looks promising, too

https://www.mathworks.com/discovery/euler-angles.html

Answer 1

[crisdeodates]

At last found a very simple solution.

Converted the euler angles to rotation matrix and rotated to unit vector.

[Adam Danz]

Congrats! If you provide a simple demo or example in your answer it will be more useful to people who may come across this post in the future.

[crisdeodates]

Sure ...

Lets say we want to visualize a vector at a given point [0 0 10] and orientation [0 0 50].

1. Convert the orientation angles to radians using deg2rad function.
2. Find the rotational matrix using eul2rotm function in the sequence (eg: XYZ) required.
3. Initialize a unit vector along x-axis as [1 0 0].
4. Rotate the unit vector using the rotational matrix obtained in step 2.
5. Plot the newly formed directional vector usingquiver3 function.