Eye position relative to center of head?

[performlabrit]

In my simulation, I am linking the mainview to the position/orientation of the head tracked by my motion capture system (in my case, Phasespace).

It is necessary that the rigid body returned by my Phasespace motion capture system is appropriately oriented for correct eye/head geometry. To check this relationship, I am writing a calibration program.

This program will allow the user to dynamically adjust the location of two small colored spheres until they surround the user's eyes, and tint the world via transparency. Finally, the parameters used to place these spheres in the correct location will be used to update the parameters of the HMD projection used in nvis.nvisorSX111().

Tentatively, the parameters used to set eye-location will include:
The assumed distance of the eyes from the center of the head (cm)
The elevation of the eyes from the center of the head (degrees)
The inter ocular distance (perhaps also degrees from the center of the head)

I've hit a roadblock early on: I need to know the position of the eyes relative to the center of the head (ie the location of the mainView).

Unfortunately, eye-locations are not explicitly stated in the HMD setup code that I'm using (nvis.nvisorSX111()). How can I calculate the position of the eye-in- head when the viewing parameters are set with nvis.nvisorSX111() command ?

[Jeff]

If you link the viewpoint to the tracker then you can use the link.preTrans and link.preEuler commands to apply position and orientation offsets between the head tracker and center point between the eyes. Use the viz.ipd command to set the interpupilary distance. The ipd value will affect the stereo separation.