## Rotation Translation

bruns
Posts: 2
Joined: Thu Sep 01, 2005 5:00 am

### Rotation Translation

Hello,

I have run the demo "Optitrack sample" which gives me the rotation and translation.
I suppose that these angles are Euler angles, right?
What about the values for position? Are these metric or only relative?

Is there some documentation about the algorithm how the position and rotation is determined?

Thanks a lot.

[ September 01, 2005, 02:00 PM: Message edited by: E.B. ]

buw
Posts: 3
Joined: Fri Sep 16, 2005 5:00 am

### Re: Rotation Translation

does nobody have an answer to this question? I would appreciate some information, too...

Thanks...

ericd
Posts: 142
Joined: Thu Nov 04, 2004 5:00 am
Location: Portland, OR

### Re: Rotation Translation

The x, y, and z values are distances in mm from the camera. The point used to calculate this position is a rough estimate of the point of rotation of a person's head. The position is calculated assuming the vector clip is placed on the brim of a baseball cap on the users head. It is calculated by taking a normal to the plane formed by the vector clip. Human head rotation is a complex movement, so this point of rotation is a simplification of the problem.

The angles returned by the API are simply the angles formed by the vector plane. Typically they are used as relative measures where the users "center" themselves to the camera.

The algorithm for determining the position of the vector clip is proprietary.

buw
Posts: 3
Joined: Fri Sep 16, 2005 5:00 am

### Re: Rotation Translation

thanks...
what exactly do the different colors of the markers in the camera image mean?
There is an option to change the color of tracked and untracked markers in one of the dialogs, but the markers also change their colors to white and grey...

vrc
Posts: 2
Joined: Fri Dec 04, 2009 5:27 am

### Re: Rotation Translation

Hello.

I have to convert the roll/pitch/yaw values into a rotation matrix. Apparently there are 6 possible conventions regarding the (Roll/Pitch/Yaw) Euler angles in use: xyz, xzy, zxy, zyx, yzx or yxz.
http://en.wikipedia.org/wiki/Yaw,_pitch_and_roll

Therefore I'd like to know which euler angle convention do you follow.

Thanks...

Birch
Posts: 1139
Joined: Thu Jan 30, 2003 5:00 am
Location: Corvallis, Oregon

### Re: Rotation Translation

Hello,

Unfortunately INPVector has not been a supported interface for a couple years now. However, there is some information below.

You may want to review the following thread :
http://forum.naturalpoint.com/forum/ubb ... #Post27668

Also note Eric's earlier answer :
"The angles returned by the API are simply the angles formed by the vector plane. Typically they are used as relative measures where the users "center" themselves to the camera."

vrc
Posts: 2
Joined: Fri Dec 04, 2009 5:27 am

### Re: Rotation Translation

thanks for the information