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The user is tracked in most CAVE systems via a magnetic tracker (usually something like an Ascension Flock of Birds). Most user-interface items such as pointers and/or steering wands are tracked in the same way. The main user can walk around the CAVE environment and the tracking program will take their position into account during rendering. Other users in the system must stay close to the main user if they want to have an immersive experience. Otherwise, their view will be skewed.

Yes, if only the military had heard of this technology sooner. They would never think of something as complex as helmet mounted displays on their own.

http://www.ascension-tech.com/applications/militar y.php
http://mae.pennnet.com/Articles/Article_Display.cf m?ARTICLE_ID=231330&p=32

And really, building this display unit and launching the "bird" is the only hard part. Integrating 3D satellite imagery with the flight control and display system in combat situations and high RF jamming environments is childs play, so these low-res consumer grade glasses are the missing piece that the military has been waiting for!

Let's send a few of these glasses over to the boys in Afghanistan to prevent any further crashes!

Ok, I'm not as religous a microsoft hater as many here, but is there ANY good reason to have this run on XP?

You'll find a lot of exotic computer gadgets you find on the net tend to use Windows. I presume it's simply because it's probably cheaper to develop for just one platform, and they choose to use the most common one. Here are some examples of fancy displays and input devices I've found on the net...

• Autostereo displays
• Panoram Technologies
• Elumens Corporation
• Actuality Systems (site seems like it's down at the moment)
• Sensable Technologies
• Polhemus.com
• Ascension Technologies

Some of their products may be compatible with other operating systems, but most I looked at have a Windows bias.

More so than just the idea of painting, is the fact that it's essentially a gesture interpretation system. If the game is decent at figuring out what you're thinking based on the way you move the mouse, maybe it'd be able to interpret other body motion too, if given the appropriate input devices.

I'm thinking specifically of the motion trackers used in the CAVE system. It's one thing for a virtual character to mimic your movements without understanding them, which has been done for years. It'd be a big step for the character to make inferences about your emotions based on how you stand or move.

The obvious pitfall here is that, after interacting with such a game for a long time, people might forget how to use the expressions that the game doesn't understand or react properly to. It's easy to keep a mental separation when the interface is very different from regular human interaction, like a keyboard. I like to think that most of us don't vocalize "lol" on a daily basis. But as the interfaces get closer to regular life, will the line blur enough to throw us off?

Here's an idea for head position tracking hardware: put a bunch of bright balls around the outside of a helmet, and have the person surrounded by a handful of cameras.

Better yet would be the use of tiny gyroscopes like this that provide 6DOF, although this one doesn't. No need for worn optical cues and cameras. There is also this product that has 3DOF, which claims to "have metallic interference virtually eliminated". I presume it is some kind of magnetic tracker that isn't as vulnerable to the weaknesses of normal magnetic motion tracking methods, which I think the grandparent poster is referring to.

The method you are mentioning using bright balls and cameras are optical motion trackers. Magnetic ones have advantages over optical ones. Optical ones have other disadvantages, and don't normally work in real-time, so they wouldn't be viable for head position tracking for virtual reality.

Infrastructure will of course have to be improved and fueling and maintenance will create a whole new segment of my industry. {Did I mention I work for an Airline, well at least that's one of things we do.} With this economy we could use the jobs! As for bad luck it will be with us in the skies or on the ground but realistically it comes down to the statistical acceptability of losses. Currently it is much safer to fly than to drive. Add more traffic in the airways and those numbers move around a bit. Hell we have an expectable amount of rat dropping in our food per FDA regulation so when the FAA says x number of deaths is an expectable variable they give the blessing. Your flock of birds comment got me remembering my days as a VR consultant check out Flock of Birds

That is great and all, but I believe the problem with all that, is that you -still- can't intereact with the 3D object you're seeing, at the place where it -appears-.

Yes you can. There are 3D input devices such as mice, joysticks, gloves, and haptic devices.

This is wrong in so many ways, I don't know where to start. The projectors for a CAVE are completely different from the ones used for the Geowall. They are usually big CRT projectors that cost around $20k a piece. If you are one of the lucky few that have 3-chip DLP projectors like the Mirage, they cost you at least $50k a piece. These are for field sequential stereo and aren't using any kind of "NVIDIA trick".

If you are using a magnetic tracker you don't have "hundreds of pounds of shielding, permanent magnets, electromagnets, etc". There is a transmitter that's about 1' cubed in size and several 1" cubed sensors. Metal tends to interfere with the tracking due to induced currents, so you want for there to be a little metal around your tracked area as possible. The 6 sided CUBE at the Beckman Insitute at UIUC is made completely out of wood for this very reason. There's usually only one transmitter and it doesn't have to be positioned very carefully. All the XYZHPR readings from the sensors are relative to the transmitter, so you just have to calibrate it once and you're good to go. Also, a magnetic tracker doesn't cost anywhere near $100k. More like $20k. Check out Ascension for their Flock of Birds which is the most commonly used magnetic tracker for immersive displays. Now, if you're using something like the InterSense tracker with their nifty new wireless sensors, it can get pretty pricy, though probably still under $100k.

• Two 5DT Data Gloves (one left, one right).
• Two Ascension Flock of Birds: again, one for each hand.

Ascension Technologies makes the Flock of Birds and related products, motion trackers based on a pulsed magnetic field. They're very accurate and quick to respond. I have no idea what they cost, I've just been on the user end of a Flock and loved it. :)

CAVERNUS
- Check out applications to download. My personal favorite is Crayoland. :) There are also some early papers about the CAVE somewhere there

CAVE QUAKE II
- Quake II in the CAVE? What's cooler then that? It's quite unnerving fighting a Tank that's literally taller then you.

Teleimmersion at EVL
- Connecting CAVEs

Welcome to CAVERNsoft
- How to connect CAVEs

Center for Parallel Computers - VR-Cube
- The 6-walled CAVE in sweden. My office-mate saw this, said it was the most immersive experience he's ever done. Forgot where he was!

Ascension Techology Corporation
- These guys make the magnetic tracker we're using.

Welcome to Polhemus!
- another type of tracker

Pyramid Systems
- they'll build a CAVE for ya

AMPRO Corporation
- We use their projectors

CAVE Programming
- Some information on programming for the CAVE

CAVEdev::main
- Some other cool projects for the CAVE

enjoy!

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