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Preliminary experience with a 3D headset

 
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PV
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PostPosted: Sun Apr 19, 2009 7:47 am    Post subject: Preliminary experience with a 3D headset Reply with quote

As mentioned in Argon's thread, I've been playing a little bit with a 3D headset I got from these guys last fall. http://www.vrealities.com/

The model seems to have been superceded, but is as far as I can see almost identical to this one http://www.vrealities.com/virtualvisor.html , though mine was called "V-Real". It came with "earbuds", and their new model has built in headphones of some sort. I use neither, as I have a good set of Koss headphones with a built in mike, so the earlier version is actually better for me.

Although I've had it for quite a while, I haven't had a lot of time to be flight simming over the winter, so my impressions are still somewhat preliminary. There's no simple summary, the unit has its good points and its bad points, so I'll sketch out what I've got so far. I have not actually tried it with SDOE. I have spent most of my home computing time doing terrain mods for BoB2 for the last couple of years, and not flying much at all, but I managed to fold in some VR headset trials into my inspections of terrain work, so my simming experience with the device has all been in BoB2. I've also tried checking out a small number of 3D images I've found on the web, but either I'm not understanding how to look for them, or there are amazingly few 3D images out there (other than the red-and-blue pairs of monochrome images, which don't work with a full colour headset anyway).

Anyway, the device: Obviously, the resolution is low as shown in the spec, 800x600, but this is not really very noticeable. My normal 17" crt monitor has a 16" diagonal actual viewing area, and I typically sit with my eyes 20" from the screen. I have a high bridge to my nose, which limits the proximity I can get the headset lenses to my eyes; the result is an equivalent screen size as if I were looking at my crt from about 26" away. I found this a wee bit disappointing. On the other hand, it means that the 800x600 is not much of an issue. I don't know how much better the angular size will get for someone with a smaller nose bridge, the effective size doesn't change much as the lens moves away from the eye, so I'd guess you'd only get an effective distance of about 24" at best.

I use the headset in conjunction with a Track IR system, and so the view in the headset follows the movement of my head. The effect is rather like "foveal" vision, you don't really miss the peripheral vision too much, though it would still be nice to have.

I initially tried to have the Track IR map my head movements 1 to 1, instead of the usual setting where you are trying to look at a screen directly in front of you, so you have the motion-translation gain set way way up, so a slight shift to the side slews the view about 120 degrees to the side. Unfortunately, I found that the TIR system will get confused at about 80 degrees rotation, as it is trying to compute orientation from the positions of three markers, a central forward one and two side ones the same distance back. This means that when you've turned your head 90 degrees, the two side markers are overlapping each other from the TIR sensor's viewpoint, so it can't deduce a head position. As a result of this, I had to set up my TIR transform function so that it is essentially 1 to 1 for about the first 40 degrees of motion in any axis [except looking up - more on that later], but then accelerates so that at 80 degrees it is giving you 180 degrees rotation. This works, and is much more comfortable, for me, than trying to use TIR with just a regular monitor, but it still doesn't provide the full degree of realism I'd like to have.

The ideal solution would be a head tracker that used gyro-magnetics and mapped head position accurately in a full 360 degrees. These are available, but the cost is up by orders of magnitude, and I have no idea what the interfacing issues are for the software. The other advance I'd like to see is a non-foveal component to the display, which would be a semicircle of radially arrayed pixels going outward from the foveal xy display in the centre, maybe adding up to a third the 800x600 number in the central display, and being radial they would get larger as they moved outward to the edges of vision, just enough to give you some basic information in the peripheral regions, where your eyes don't have much resolution anyway. As 3D headsets are a tiny market yet, and all displays are currently simple xy rectangles, this advance is going to take a while to appear, but I can't see how it won't be brought in eventually , as it is really the only good solution for headset peripheral vision.

Um, OK, so how does it look, and work, overall? I guess I should mention that when I first got mine, it seemed to have some serious bloom in the lower left corner of the display. It wasn't due to the pixels themselves, as I could mitigate it somewhat by squeezing my viewpoint to the upper right corner of the eyepieces; it was clearly due to some misalignment in the construction of the optics. I was sorely tempted to dismantle the thing so I could fix it and learn about its construction at the same time, but at $750 and wedged together so it seems I would have to break something to get it apart, I deferred and requested a warranty repair. The response was prompt and most effective. I did have to pay shipping one way, but the unit (or a replacement?) appeared shortly, and has worked properly since.

The display appears as a rectangle in a black field. There are no eyepiece/lens adjustments available, but the view is adequately in focus without them. I thought I might need to use my glasses, but the display turns out to be clearer without them - I need glasses for far distance > about 4 feet, and the effective distance of the headset display is about one foot. The brightness range is a bit limited; the black level is up a bit, I don't know how well they would work for a night scene, I haven't tried them. There is brightness control, but at minimum it is still pretty bright; it seems the backlight isn't tied in to the brightness system so you can't get any really substantial dimming. Within its limitations though, it provides an adequate, though not stunning image. The colours are a bit of a problem, in that they wash out easily at high brightness, but when dimmed, terrain seems to darken too quickly relative to sky. It may be I just haven't spent enough time researching things I can tweak (somewhere?) to get a better appearance.

When used with the TIR system, the ability to look around the cockpit and out the windscreen in all directions with a fairly directly corresponding head motion throughout most of the forward view, is quite immersing. In BoB2, I can open the cockpit of my spit and lean out, and look down, which is quite a novel effect. And the adjustment to the motion correspondence to get the rearward views to work is not that disrupting. I find I don't use them much anyway, except looking up; I often stand a plane on its wing and run around in a circle at about 750ft in order to locate the enemy when I'm playing with full realism, and I use the full area of the windscreen "above" me (which is now providing a view along the horizon), and in that case the variation in the motion is quite noticeable. Particularly as the angle change for looking up has to be greater than the adjustment for any other direction, as the TIR markers sit on the top of your head, so as you look up they can become occluded - I have mine propped up as high above my headphones as I can to compensate for this, but still to can only tilt up about 45 degrees, so the adjustment there is pretty steep. I have about 40 degrees set to map as about 110 degrees, which is the max I have for looking up (in TIR you can set the two sides of an axis, in this case up and down, to have separate transform curves).

There are two separate aspects to a VR headset experience. One is with the world being tied to head position, so you can look around and see different parts of the world through the headset. The other is the true stereo vision, where things appear three dimensional because the view to each eye is different. These are separate functions, and don't automatically follow together. Using viewing software for looking at 3D images, like an old Viewmaster, the image sits in the viewscreen no matter how you move your head, but the 3D effect gives the objects in the image 3D shape. Alternately, you can run a flight sim and have your view cued (via Track IR or similar device) to your head position, so the neadset provides you with views of different parts of the virtual world as you move your head, but unless you have a 3D driver for your video card, you will not have different views to your two eyes, so you won't see objects as having 3D volume.

As far as I have read, ATI cards have not had 3D drivers. nVidia cards do, but there are only a small number of them, and nVidia is now only supporting 3D drivers for Vista, so you need an older driver for XP. The headset came with a copy of nVidia v91.31 driver plus mating stereo driver (you need a regular driver plus a stereo driver). The last XP compatible stereo driver doesn't seem to be on the nVidia site any more, but can be had from guru3D.com; it is v162.50, and will work, so it says, with any 16x.xx nVidia driver.

Anyway, in many respects, the actual 3D vision is not much of an aid in a flight sim. It is certainly an immersion boost, as the cockpit becomes a seemingly substantial 3D object, but the world outside the cockpit is all too far away to benefit from the 3D effect. The only advantage you have is the ability to see a bit around the posts of the windscreen structure, and in truth, most sim cockpits already simulate this effect by making the posts thinner than they really were. In many cases flying would be really difficult otherwise, especially combat sims - the posts holding up the bulletproof front panel on a spitfire are immense, and are always modelled thinner to compensate for the real pilot's ability to see around them because he has two eyes.

I mention this because the 3D routines, even for a 600x800 image, take a significant amount of computing. I have an old Athlon 3000, with a 7900GT. I can notice a bit of FPS drop when looking about with 3D enabled (generally the nVidia drivers allow 3D to be toggled on and off by a key press). I think that many folk would be happy to run in most cases with the 3D turned off, as the head-controlled view is benefit enough.

Well, I've probably forgotten lots of things, and as I say, I haven't had a lot of experience with it so I don't have all the answers, but this should provide a pretty good introduction, and I've been typing for quite a while, so I'll stop here.
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ArgonV
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PostPosted: Sun Apr 19, 2009 7:29 pm    Post subject: Reply with quote

Very good review! You are very thoro in your testing thus far... I for one can't do 3d headsets because I have too much going around my PC desk (What button to press on my stick and keycards to read).
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PV
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Joined: 24 Dec 2002
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PostPosted: Mon Apr 20, 2009 1:20 am    Post subject: Reply with quote

Yes, finding your way around the workspace is definitely an issue. The eyepieces are on a flip-up front section, but you need a free hand to work it, then presumably use the other to do keystrokes, whatever, it's somewhat awkward. Because mine sits up on the bridge of my nose I can see down to the keyboard under the eyepiece somewhat, but not really enough to be completely useful. You really need to have all your most common controls mapped to the joystick, and a level of braille facility with the keyboard.
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