Columns of a Quaternion

Troubleshooting General Help
1

Hello!



I have a mathematical question regarding the columns of a Quaternion. I believe I found out that Column 0 means the "left"-axis, column 1 the "up"-axis and column 2 the "direction"-axis of a Quaternion.  Now my questions:



Is that correct?

Does this correspond directly to the local-coordinate-system of the node?

Does left correspond to x, up to y and direction to z?



Greetz

Tom

2

No. A quaternion has no columns: http://en.wikipedia.org/wiki/Quaternion



Do you mean a matrix? Then yes, it might. It might also hold anything else in its columns, depending on context.

3

"A Quaternion has no columns"


  • and thats the reason for my question. I read about Quaternions at Wikipedia, so I was even more confused about the Method "Quaternion.getRotationColumns()". Does this method convert the Quaternion to Matrix-Representation and return the chosen Column? And do these Columns represent the x,y,z-vectors of the local coordinate-system relative to the parent coordinate-system?
4
uncl3t0m said:

"A Quaternion has no columns"

- and thats the reason for my question. I read about Quaternions at Wikipedia, so I was even more confused about the Method "Quaternion.getRotationColumns()". Does this method convert the Quaternion to Matrix-Representation and return the chosen Column? And do these Columns represent the x,y,z-vectors of the local coordinate-system relative to the parent coordinate-system?


Bump, because I also wonder what the method Quaternion.getRotationColumns() does exactly. What are those 3 columns?
5

It returns the requested column of the rotation matrix of the quaternion. I only looked briefly at the source, but I think that is what it does.

6
Tobias said:

It returns the requested column of the rotation matrix of the quaternion. I only looked briefly at the source, but I think that is what it does.


I also thought that, but I'm not that firm with quaternions. Do these 3 columns form a rotation matrix that is exactly the same as a classical 3x3 rotation matrix? Like one of those you use all those years before you discover quaternions? ;)
7

:wink:

Yeah, I think it is. Look at the source and compare getRotationColumns() and toRotationMatrix() or whatever it's called. Seems mighty similar.

8

I'l have a look, thanks  8)