View Full Version : Virtual Reality Applications für HMD's

05-11-2004, 05:35 AM
Has anyone developed virtual reality programms für HMD's ? Could you give some advice or a link?

It should be a very basic application (3d-cone or starfield) displayed with a HMD.

What do I need? Which programs or tools?

05-11-2004, 05:39 AM
what's HMD?

05-11-2004, 05:41 AM
Sorry, I mean Head Mounted Displays.

05-11-2004, 05:45 AM
oh. i dont know but sounds very intersting! can you tell us more?

05-12-2004, 09:47 AM
I have worked with HMDs.

You typically have two OpenGL views being rendered. There is a virtual eye separation viewing offset between the eyes and the fields of view etc are determined by the physical characteristics of the HMD display device. The video for each eye can be generated in different ways depending on your graphics & video hardware & formats. You could have two separate videos from two separate graphics systems. You could have two videos from different viewports on a single graphics system. You could have overlapping viewports combined in a single video signal using quad buffer stereo or some form of interlacing or interleaved video stream (the latter is less common for HMDs).

The eyes are typically attached in a transformation hierarchy to a head transformation, the position and orientation of the head transformation comes from a head tracking device.

The eye positions/offsets are relative to this head origin and can be adjusted to accomodate the users. During the adjustment of the IPD (inter pupil distance) a 3D test pattern can be used to allow the user to determine when things are callibrated correctly.

The fields of view for each eye should be available form the manufacturer and there will almost always be some region of stereo overlap in the center between the eyes with some region of non overlap mono on the periphery. Some high end HMDs allow this to be adjusted.

It is absolutely critical that you understand the geometry of the HMD's effective field of view and that you match it based of first principals in the graphics system. If you're fumbling with numbers & guessing & fudging projection matrices then stop & study the problem till you understand it.