CCW euler angles to CW euler angles

CCW euler angles to CW euler angles

Post by Rune Laurse » Sat, 28 Apr 2001 07:14:29



Hi,

Can anyone tell me how to transform counter clockwise euler angles to
clockwise euler angles?

regards,
Rune Laursen

 
 
 

CCW euler angles to CW euler angles

Post by Rene Tschaggela » Sat, 28 Apr 2001 16:43:44


isn't it 360deg-(your angle) ?

Rene


> Hi,

> Can anyone tell me how to transform counter clockwise euler angles to
> clockwise euler angles?


 
 
 

CCW euler angles to CW euler angles

Post by Rune Laurse » Sat, 28 Apr 2001 17:53:45


Ok, I didn't explain the problem well enough. I am using a headtracker which
returns it's viewing direction in 3 euler angles. One of the angles is in
the range -90 to 90 and the other two is in the range -180 to 180. The
angles are measured counter clockwise. I have a function that converts these
angles to a counter clockwise rotation matrix. I need a clockwise rotation
matrix, so I figured that the euler angles would have to be converted to
clockwise before converting them to a rotation matrix. Is that the wrong
approach?


> isn't it 360deg-(your angle) ?

> Rene


> > Hi,

> > Can anyone tell me how to transform counter clockwise euler angles to
> > clockwise euler angles?

 
 
 

CCW euler angles to CW euler angles

Post by Hans-Bernhard Broeke » Sat, 28 Apr 2001 19:52:33



> Ok, I didn't explain the problem well enough. I am using a headtracker which
> returns it's viewing direction in 3 euler angles. One of the angles is in
> the range -90 to 90 and the other two is in the range -180 to 180. The
> angles are measured counter clockwise.

That doesn't make sense without a definition what side these 3 clocks
are supposed to be facing.  Remember that a clock's hand will appear
to rotate CCW if you're looking at the back of the clock.

Quote:> I have a function that converts these angles to a counter clockwise
> rotation matrix. I need a clockwise rotation matrix, so I figured
> that the euler angles would have to be converted to clockwise before
> converting them to a rotation matrix. Is that the wrong approach?

This description still doesn't make much sense, I think.  There is no
such thing as a clockwise rotation matrix.  

To convert any triplet of Euler angles into a rotation matrix, you
have to know *exactly* how these Euler angles are defined, so you can
reflect that knowledge by chosing the right axis direction vectors in
the formula:

        M := R(axis1,angle1)*R(axis2,angle2)*R(axis3,angle3)

CCW vs. CW rotation can be implemented in this setup by flipping
either the sign of the angle, or the direction of the axis direction
vector.
--

Even if all the snow were burnt, ashes would remain.

 
 
 

1. euler angles to axis/angle

I would like to convert 3 euler angles that I'm using to define the
orientation
of a 3d mesh object to an axis/angle representation, so I can call
glRotate(angle, axis)
to rotate the 3d object without suffering from this gimbol lock
thingy-mcbob.
Can anyone here tell how to do this ?
I'm using the right-handed coord. system like OpenGL's.

Thanks,
--Rick

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