HMD hardware questions

[astralpancakes]

Hello everyone!

I'm currently in the process of putting together a new machine for myself (I currently have the case and a DVD drive, hehe, most of the crucial parts will come next month). One of the things I want to be able to do with it is dabble in stereoscopic 3D (or "virtual reality" if you will) for various art projects.

Basically, I'm looking for a set of HMDs that can do stereoscopy in "any" game engine (thinking of using the Blender engine, which seems to have some sort of support for stereoscopic rendering in its settings, although I'm not sure if that's relevant). Built-in head tracking and some sort of simple SDK that would let me implement it would be nice as well, although I guess I could build my own accelerometer if it came down to that... Oh, and my main OS will be Linux, so it would be nice if it worked in that, although there's nothing preventing me from booting into Windows I guess.

I've mostly been looking at the Vuzix VR920 since it's cheap-ish and has built-in tracking which someone seems to have hacked together a Linux driver for. People seem to prefer the eMagin Z800, which seems to have the same features with a nicer and bigger display, at the cost of a higher price and worse Linux support.

I guess both of these require pre-series 8 nvidia cards, right? Unless I want to try the hacked drivers for Windows. Does anyone have experience using either of these with the official nvidia drivers under Linux?

At first I thought I had to get an nvidia Quadro card, since (most of) those have something Wikipedia calls a "Stereo display" feature, but I guess that's not the case? Can anyone tell me what that would be, since I'm feeling a bit confused.

Thanks

[cybereality]

I've got the VR920, its not such a bad device. It still falls short of what you expect from movies like The Lawnmower Man, but it works good enough. I have only used it on Windows though, never on Linux. It worked with the old Nvidia stereo driver under XP and now it is also supported by the IZ3D driver with modern hardware on Windows. The Z800 is a slightly better HMD but not by that much from what I understand. If its between better support and a slightly wider FOV (not to mention the price) then I would say go with the better support. I played around with the VR920 SDK in C++ and it seemed simply enough to work with. At least adding headtracking to the 3D engine I was using (OGRE) was pretty straightforward. The 3D feature on the Quadro cards is for OpenGL quad-buffer, which I guess should work on Linux but I don't know much about it. I have mainly experience with the consumer 3D drivers on Windows so I'm sorry I can't help you more.

[crim3]

The main issue with the vr920 is the crappy head tracker. The one in the z800 is a lot better, but this HMD is too expensive in comparison.
A guy did a linux driver for the z800 but I never tried it. Anyway, I think is better to implement an optical tracking system than using accelerometers. You need really expensive accelerometers for decent head tracking or there will always be drift due to the lack of an absolut reference.
Another good thing with the z800 is that is has a very low power consumption and is powered through USB.

After 2 years with my z800, when I compare my experience to what I see in those CAVE videos I feel like HMD is not yet the way to go. Looking through a hole is not what I'd call immersion despite the perfect stereoscopic graphics that you have in a HMD. They must create HMD's with a lot more FOV, then they'll be worth. That's my opinion as a former virtual reality, HMD, data glove and all that stuff fanatic.

By the way, I don't know if you can have stereo graphics in linux in the way of nvidia's generic stereo driver.

[astralpancakes]

Well, HMDs are a stopgap until I get something that plugs into my optic nerve is a stopgap until something that plugs into my brain stem is a stopgap until I can upload my mind into a computer..

Anyway, yeah, I found the Linux drivers for the z800, but they seem to be pretty primitive with no updates for the past two or three years. Might just end up building my own tracker with an Arduino and some accelerometers...

It seems like you have to have a Quadro to get stereo 3D in Linux though. On Geforce it's pretty much centered around DirectX. And apparently the pre-series 8 only in Windows XP is for Geforce cards, Quadro has no such porblem in either Linux or Windows. If anyone knows more about this, please confirm/deny.

Anyway, thank you for the help guys.

[Xerion]

Hmm I really should try whether the VR920 will work with new nvidia drivers if I have the emitter connected and force 60 Hz. Tbh they have been in a drawer for a few months now for my projection rig gives much more fov and things actually look lifesize. My brain is just never fooled by the VR920; I can see how far the screen really is so my brain calculates the height of things ingame corresponding to that I think. I wonder if there will be a HMD where this is not the case.

[crim3]

until I can upload my mind into a computer..

I've just finished a book where people (and other intelligent lifeforms) can updaload their minds into a spacial probe that is then launched at high speed with antimatter engines and when they arrive to another star system their bodies are re-built by robots that can manipulate matter at the atom level. Cool, isn't it?

Haven't you considered optical tracking? With accelerometers you have to read the data to integrate velocity and from that, position. You need very consistent accelerometers and read them at a high rate, and still you'll drift with time due to sampling, floating point precission and timer precission. And for orientation you need gyroscopes and also double integrate the data with time. Not a trivial task, though I admit that can be fun.

I love the concept of wearing the displays in my face so I can look anywhere as if it would be real life, but in the last year I've been reading comments about projectors like that one from Xerion in the las post, and that's why I'm thinking more and more of leaving my z800 aside and jump to a projector rig. It's all about field of view, really. For me is the key. And the barely 33º of horizontal field of view of my z800 is ridiculous.

[Okta]

If you want good head tracking for a reasonable price just get a gyration mouse and strap it to your head. They are very good for this as they like to rotate instead of pan.

See teh "Game Gun" man for example, although he pans with it which it doesnt do as well as rotate in position like you want with head tracking.