Quaternions and rotation vector.

In summary, the conversation is discussing how to calculate a normalized 3d vector from a quaternion, with one person suggesting using the imaginary elements associated with i, j, and k, and another person clarifying that a quaternion is itself a vector.
  • #1
pjhphysics
16
0
Hi,
I'm trying to calculate a normalized 3d vector representing the quaternion's orientation. Can anyone give me a hand?
Thanks!
 
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  • #2
It's easy. Take the vector part of the quaternion and then normalize it.
 
  • #3
What constitutes the vector part of the quaternion?
 
  • #4
He means use the imaginary elements associated with i, j, and k of course.

BTW, technically a quaternion is itself a vector, since it's a member of a vector space.
 
  • #5
A quaternion can be expressed as

q = q0 + q1*i + q2*j + q3*k

It's a 4-vector, (q0,q1,q2,q3) that can be decomposed into a scalar part, q0, and a 3-vector part (q1,q2,q3).
 

Related to Quaternions and rotation vector.

1. What are quaternions and rotation vectors?

Quaternions are a mathematical concept used to represent rotations in three-dimensional space. They consist of four complex numbers and can be used to perform rotations without encountering the problems of gimbal lock. Rotation vectors, on the other hand, are a simpler way of representing rotations using just three numbers (x, y, z) and a magnitude. They are commonly used in computer graphics and animation.

2. How are quaternions and rotation vectors related?

Quaternions and rotation vectors are both mathematical representations of rotations. Quaternions are more complex and can represent any rotation, while rotation vectors are simpler and more intuitive but are limited in their representation of rotations. Quaternions can be converted to rotation vectors and vice versa.

3. What are the advantages of using quaternions for rotations?

Quaternions have several advantages over other methods of representing rotations, such as Euler angles. They do not suffer from gimbal lock, which can cause unexpected behavior in certain situations. They are also more compact and efficient to compute compared to other methods. Additionally, they can smoothly interpolate between rotations, making them useful for animation and 3D graphics.

4. How are quaternions and rotation vectors used in computer graphics?

Quaternions and rotation vectors are commonly used in computer graphics to represent rotations of 3D objects. They are used in animation, video games, and computer-aided design (CAD) software. They are also used in physics simulations to model the rotation of objects.

5. Are quaternions and rotation vectors difficult to understand?

Quaternions and rotation vectors can be more challenging to understand compared to other methods of representing rotations, such as Euler angles. However, with some basic knowledge of complex numbers and vector algebra, they can be understood and used effectively. Many software libraries and programs also provide functions to handle quaternions and rotation vectors, making it easier to use them without fully understanding the underlying mathematics.

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