Hemisphere settings

[s.chaplain]

Hi.
We have an issue regarding the use of Optitrack as a tracking system for a Virtools application. The VRPN communication works fine, and the reading of the rigid bodies position is OK (translations do work). However, we are experiencing a problem with the orientation values.
Basically, after calibrating the axis, both translations and orientations should be OK. But our rotations are inverted (ie : turning left the rigid body turns it right in Virtools). Of course, if we reverse the side of the rigid body (ie : putting the bottom face on top), it works.
But, as explained in the Virtools documentation :

"If you're experiencing rotation problems, but not translation problems, you might want to check the Hemisphere settings within VRPN or within the configuration application of your tracker"

My question is what do the "Hemisphere settings" exactly mean? And is it possible to change these values with Rigid Body?

Thanks.

[beckdo]

Ok, there are two things that could be coming in to play here:

1. The coordinate system is, by default, a left-handed coordinate system. In the options you'll find a check box that will toggle the data to a right-handed coordinate system.

2. Take note of the orientation you have the rigid body when you initially create the rigid body as the yaw/pitch/roll axis are based off this initial orientation with respect to the world coordinate system.

[BernhardSp]

Hi,

What is the correct initial orientation of the rigid body when it is created? Is there any diagram somewhere as to how the Optitrack rigid body frame (the real object) should be oriented with respect to the world coordinate system to work correctly?

Thanks,
Bernhard

[BernhardSp]

Hi,

Sorry, I was referring to the beta version of the tracking tools, which I got from support because of problems with VRPN and other protocol streaming unable to stream frame with the official release of the rigid body toolkit.
In the official release there is the possibility to set the origin of the rigid body in the software. Unfortunately this feature doesn't seem to exist yet in the beta version while the streaming works fine in the beta.

Thanks,
Bernhard