MATLAB: Visualise direction 3D vector defined by two angles

3d vector defined by two angles

I'm an almost complete MatLab novice, and would like to visualise in 3D the direction of a vector defined by two angles. Specifically, I have (1) a 'frontal' plane angle (in degrees- as if looking from the front), where 0 degrees is along the conventional x-axis, positive angle is defined in the clockwise direction, and (2) a 'horizontal' plane angle (in degrees- as if looking from above), where 0 degrees is again along the x-axis, positive angle defined in the clockwise direction such that +90 is orthogonal to the frontal plane.

I have been trying to write a basic script that will show an arrow from the origin to the direction of the vector (magnitude is not important)- I suspect it is trivial but I have been failing!

Best Answer

How about something like this,

[u,v,w]=sph2cart(-angle1*pi/180 , pi/2-angle2*pi/180, 1);
quiver3(0,0,0,u,v,w)

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MATLAB: How to get direction for 3d angles between 2 vectors

You will need to define in your code which direction is the clockwise and which is counterclockwise. You can do that by defining up front a normal vector to your 3D plane that can be used to distinguish this. E.g., something like

PlaneNorm = a 3-element vector defining the normal to the 3D plane for counterclockwise direction
ang = atan2d(norm(cross(v1,v2)), dot(v1,v2)); % angle without regard to "direction"
if( dot(cross(v1,v2),PlaneNorm) < 0 ) % if v1 X v2 is on the other side of the plane
    ang = 360 - ang; % modify based on desired "direction"
end

MATLAB: What is the rotation sequence for the Euler angles in the Quaternions to Euler Angles block in the Aerospace Blockset

Documentation on the Quaternions to Euler Angles block (for the default sequence of rotation for the Euler angles) is missing from the Aerospace Blockset manual.

Here is additional information on the Quaternions to Euler Angles block:

The sequence of rotation for the Euler angles is 3-2-1. The angles are output as Roll, Pitch, Yaw (X, Y, Z).

Best Answer

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MATLAB: How to get direction for 3d angles between 2 vectors

MATLAB: What is the rotation sequence for the Euler angles in the Quaternions to Euler Angles block in the Aerospace Blockset

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