Stereoscopic 3D

Why Big Helmets Still Rule

Size matters! If you ask the manufacturers of Head Mounted Displays over the past 15 years, they would echo that mantra, but it’s SMALL size that they’re boasting. Indeed, those tiny little eye glasses size VR displays look cool (from the outside), but from the inside you’re looking through a distant window. It’s hardly immersive. Read on for an explanation why bigger is better when it comes to immersion.

This illustration demonstrates why you need large lenses and therefore large displays in order to achieve very wide field of view. You’re looking at a top view cross-section of the eyeball, lens, and display. The blue lines show the extreme periphery of an unmoving eyeball’s horizontal field of view. The dim red lines demonstrate what happens when the eyeball turns to the left.

Lens and Eyeball

So… getting back to the unmoving eyeball. The lens (or multi-lens optics) is fairly close to the front of the eye, certainly as close as your sunglasses would be. The lens needs to have a diameter that is large enough to intersect the blue lines in order to allow us to see the display at that field of view. You must look through the lens for all possible angles, not around it!

Human anatomy permits extremely wide field of view because the eyeball can rotate around its center. The dim red lines show the maximum field of view with the eyeball turned to the left. Another problem is encountered: the lens must be bigger because the eye rotates around it’s center, not around its own biological lens.

Perhaps the lens could be made smaller and moved closer to the eye? More problems occur. The turning eye issue becomes magnified. Also, the lens must be aligned much more precisely with the eyeball.

We could potentially solve the turning eye problem by fabricating the lens as a contact lens, but this would require a very high diopter lens to work properly with a small display; unfortunately beyond what is possible with current contact lens technology. Furthermore, since the display is not physically coupled to the contact lens nor the eyeball rotation, the display must still be large enough to encompass all the possible rotations of the eyeball. Finally, the contact lens approach makes it difficult to transition between the virtual world and the real world, as the contact lenses must be removed and applied each time.

Now here’s the gotcha. For a display panel of any given resolution, when it is displayed at a wider field of view, it will look grainier than if displayed with a narrow field of view. You can test this one in the comfort of your own living room. Watch your beautiful 50 inch 1080p TV set from 10 feet away. Looks pretty good, huh? OK, the picture doesn’t exactly fill your visual world, in fact, most of your vision encompasses those left over pizza boxes and the other trash that you forgot to clean up last night.

Now park your nose about one foot away from the same TV set. Wow! That’s immersive! You’re getting something like 110 deg. FOV. Uh oh! What are all those dots on the screen? Sure looks fuzzy. Same 1080p resolution that looked great a moment ago at 10 feet now looks low res and grainy.

Why do you think Head Mounted Display manufacturers love narrow field of view?

It’s All In Between The Eyes

If you look yourself in the eyes, you’ll start to realize that your eyes and your head are different than anyone else’s. The spacing between your eyes, known as the interpupilary distance is about 65mm, but this varies from 50mm to about 75mm, depending on who’s eyes you’re looking through. Also the position of your eyes, relative to the shape of your head is unique; some people have eyes that are more inset, or perhaps bulging outward.

The designers of VR helmets have to deal with all this variation in the human phenome. Everyone has a sweet spot where the two lenses of a VR helmet are perfectly aligned with their eyes. Similarly, each of us want the lenses to be positioned as close as possible to our eyes (to achieve wide field of view), without discomfort. If you wear eyeglasses, you need to have room to fit your glasses between your eyes and the lenses.

So… let’s look at how one helmet design deals with these issues:

State of the Art…Sadly

Over at Meant to be Seen 3D, in answer to a forum post looking for the perfect HMD, board vet, cybereality took the time to respond in depth…

Money quote:

Well, sadly to say it, you will probably be waiting for a long time. There is nothing I know of on the market that fulfills the Virtual Reality fantasy of the 1990’s, and in many ways the stuff they had back then was even more advanced then most of the stuff on the consumer market today. Even if you look at medical/military $20k HMDs, they still don’t even have full HD resolutions or the kind of FOV you would expect in the year 2010 (almost 2011 now). I mean, there have been some interesting research projects in academia, but nothing that could actually play a retail video game out-the-box. At this point I am think about building a DIY HMD myself, and some other members on the forum have already started projects. It just seems that the market is not ready for a consumer level VR device (meaning a headset and any accompanying peripherals). In recent years it seems that Augmented Reality (AR) is gaining popularity and is probably where the industry is headed. So I think a see-through AR-based HMD may have a place in the market in the near future. But the traditional idea of a encompassing display helmet and data-gloves seems to be fading (as much as I’d like it to be real). Hopefully there will continue to be progress in this field.

Read the full post for more…

Siggraph ’95 – Upon Further Observation

Who can remember doing all their 3D animation in MS-DOS? Back in the day, there was Gary Yost’s 3D-Studio (not Max!) licensed to and supported by AutoDesk. Now, who remembers creating stereoscopic animation with 3D Studio? VREX had a great little plugin that setup linked stereo cameras and let you render twice, once for left and again for right. Much fun on a 386!

In sorting through a carton of old BetaCam-SP tapes from the mid ’90s, I came across a non-so-cute animation I produced with the ever imaginative (and twisted) Steve Speer for Siggraph ’95. “UFO” (Upon Further Observation) defies categorization… so get out your red/cyan glasses and watch out for the a**l probe!

At Siggraph, UFO was shown in a bank of a dozen Virtual Research VR-4 helmets with shaker seats.

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And for those of you nostalgic for the days of animating in MS-DOS….

Flight Helmet – Redux

IMHO, the Virtual Research Flight Helmet was, and still is, the ultimate head mounted display, except of course, it needed modern high resolution LCD panels. Otherwise, it had incredible field of view, great ergonomics, and unbeatable LEEP optics. I came across a more complete brochure including the retail price list (starts at $6,000.)

Flight Helmet side view

photo: Raz Fairlight

Flight Helmet Optics

photo: Raz Fairlight

One unusual aspect of the Flight Helmet was that the left and right images don’t completely overlap, producing a wider image than the normal 4:3 aspect of NTSC video. If you wanted 100% overlap, you needed to purchase prisms (3M Press-On Fresnels) to shift the images horizontally into alignment. To run the helmet monoscopically, the prisms are a must!

Retrospective photo review of Forte VFX1 Virtual Reality system

Forte VFX1 was the most advanced, complex and expensive consumer VR system that appeared on the market during VR craze in mid-nineties. Introduced in 1995, VFX1 was in the shops all around the world in 1996.

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Hardware overview

System consisted of:

  • Stereoscopic HMD “VFX1 headgear” with built-in 3DOF head-tracker from Honeywell, 45 degree diagonal FOV optics with plastic lenses, 180k resolution LCD screens from Kopin, integrated high-quality stereo headphones from AKG, and microphone;
  • Rugged gyro-joystick “Cyberpuck” with built-in 2DOF tracker and 3 programmable buttons (there was reported that not all VFX1 systems were sold with Cyberpuck);
  • To make this all stuff work – system’s “VIP” card need to be installed into ISA slot of the host PC. VIP card worked in pair with PC’s video-card connected via VESA bus to provide stereoscopic imagery on both screens of the HMD. VIP card also processed all the tracking data, and redirect sound to headphones. It also introduces Access Bus hub.

VFX1 was one on the first VR systems that were sold in former USSR countries. It was very pricy for common consumers here (with starting price in Moscow – 1495 USD), but nevertheless exported VFX1 systems were sold in big quantities. Many years after I was lucky enough to get my hands on such complete exported package, originally sold in Moscow, it have additional Russian manual not included in traditional US version.


Let’s take a close look on VFX1 packaging arrangement. VFX1 was packaged in relatively small box (38x33x34 centimeters), with bunch of colorful pictures and a lot of self-advertisement, but its Virtual Reality isn’t it? Here, take a look.

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My box was damaged a little – plastic handle was broken, so for transportation purposes box were glued with scotch tape.

Buy a VR system and get free CD-ROM! Hell yeah, funny today but in 1995 this message had sense.

Package included:

  • VFX1 helmet
  • Detachable strap to helmet adjustments for smaller head sizes
  • Helmet data-cable
  • Cyberpuck (gyroscopic game controller) with Access Bus connector
  • VIP ISA board
  • VESA cable (for video-card attachment)
  • Audio cables with simple jack’s for headphones and microphone
  • Floppy disc with drivers
  • “Free CD-ROM!” with game demos
  • User manuals English and Russian versions


VFX1 helmet was somehow bulky but well designed and well balanced; nowadays many VR enthusiasts put modern HMD internals in VFX1 shell for comfortable fit. Personally I prefer modern glasses-like design, but I admit – VFX1 sit’s pretty comfortable on my head.

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VFX1 helmet had “smart visor” that can be opened to allow user to look at the outside world, while not taking off whole helmet. This visor working pretty similar to VPL EyePhone visor which were used in “Lawnmower man” movie.

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Visors optics are adjustable, you can change IPD and focal distance for each eye independently. There are no knobs or something to change IPD, you need to gently move oculars along the internal rails manually. Also rubber eyepieces on the oculars are easily detachable.

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Glass optics upgrade was available for additional price, unfortunately nearly impossible to found improved VFX1 oculars today. Insides of the helmet covered with detachable soft foam glued-over with fabric.


Is gyroscopic joystick, hold in mid-air, designed to play VR games while standing on foot, absolutely great with Quake. It have 2DOF tracker (Pitch and Roll), and 3 programmable buttons. Pretty neat accessory, too bad it utilizes Access Bus connector and it’s impossible to use it on modern PC’s without being re-wired.

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Other accessories

Among other accessories that can be found in package – is helmet head-strap, 2.5 meters VFX1 data cable, original Forte floppy disk with drivers, and user manuals. VFX1 data cable is actually standard RS-232 26 pin Male-Female cable, which is very flexible. Nowadays it’s very hard to find such cables as spare part, even in specialized cable shops.

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This particular cable marked with Forte logo, and had two warning flags:

“Do not use the VFX1 for more than for 15 minutes at a time (take frequent breaks) make sure the volume is turned down before putting on the VFX1 refer to manual for additional information”

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Pretty good ad for a 1500 bucks device isn’t it? I suppose this was one of the show stoppers for VFX1, who will spare so much money on the gaming device that you can’t use more than 15 minutes at a time? But, it was good and pretty functional limitation for gaming arcades, where people play for short periods of time.

VIP board and cable connections

As mentioned earlier VIP board need to be connected to ISA slot, provides Access Bus hub, processes tracking data from head tracker and from cyberpuck. Through VESA connector it provides video signal to helmet. Access Bus was actually a predecessor to more useful standard – USB, it also provided possibility to connect many devices through the hubs (and through each-others), make hot connections on already working system (yep, that was a big step forward in RS232 COM era). However Access Bus didn’t stayed long, and I know only one device that uses it – it’s Cyberpuck.

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In my system VIP card is connected via VESA to S3 Trio, it’s the most powerful video-card that provided proper VESA signal, compatible with VFX1. I found mentions from VFX1 users that proper VESA was also on Voodoo Banshee 3D accelerators, but I didn’t have this card and can’t test this.

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Cyberpuck can be connected to VFX1 helmet or directly to VIP card. I prefer HMD connector because it allows playing on foot.

Turning the system on

We examined particular components of VFX1 system, and now let’s connect them together and take a look on the visor’s imagery.

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VFX1 works in Windows only in 640 x 480 x 256 colors mode. Actual LCD’s (789×230 color elements) can provide wider range of colors, but utilizing VESA for transferring image to HMD – limit’s it to 256 color palette. But, this palette isn’t fixed, it’s optimized, this means that it holds any color from true-color palette, as long as palette length itself no longer than 256 colors. My VFX1 unit was used frequently in the past, but LCD’s are still bright and colors are vivid.

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I’ve tried to take a few shot’s of what can be seen through VFX1 optics, it is much sharper and with fewer distortions in reality than on these photos. But anyway take a look on the desktop and on a few game-shots from Quake, Descent, and Heretic. These games are my favorites for VFX1, especially Quake1 which gives great immersive feeling even today. By the way VFX1 do not utilize depixelation filters (in contra verse to many professional HMD’s at the time), so black-spacers between pixels are clearly seen.

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For stereoscopy, VFX1 supported two formats of input video – line sequential, and horizontal stereo-pair. While for running VFX1 in stereo-pair mode you need to use proper software, you can set VFX1 to force line sequential mode in windows configuration software, or use command line “VFX1.COM +t” to turn it on in DOS.

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Crysis stereoscopic screenshot in line-sequential mode, suitable for viewing through VFX1


VFX1 have drivers compatible with DOS, Windows 95 and Windows 98. I’ve installed VFX1 in Windows 98 SE system, and it works there without issues. After hardware installation, you need to properly configure VFX1 software to make it work. When installing software, you’ve instructed to set IRQ settings according to DIP switches positions on VIP board. You can also check tracking for HMD and Cyberpuck. Personally I’ve liked VFX1 DOS software more for its fancy graphical 3D look, but Windows version of VFX1 configurator work pretty the same.

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One of the features that I liked in VFX1 better than in its “grandson” –VR920, that tracking need to be calibrated only once, software calibrate magnetometers automatically you only need to  choose your geographical region. After calibration – VFX1 tracking worked perfectly for me, and there’s no need in further recalibration.

To make game to support all VFX1 features you need to have proper game patch, in rare cases game have built-in VFX1 support (like Descent, System Shock or ZAR). In all other cases you can use VRMouse – native VFX1 mouse emulator, which emulates mouse and key presses for trackers and buttons of Cyberpuck.

Design benefits

VFX1 had many benefits in its release time. Other consumer VR systems at that time provide fewer features; all of them were without any sort of game-controller that allow you to play standing on foot, sometimes with lack of good head-tracking (like “CyberMaxx”) and stereoscopy support (like “Philips Scuba”). Only “I/O Glasses” had both 2DOF tracker and stereoscopy, but it lacked in game support at the moment of release and had inferior picture quality. Besides VFX1 had biggest FOV among other consumer HMD’s.

Overall VFX1 offered immersive experience and wide support of currently available games at the time. Stylish, comfortable and well balanced HMD design received positive critics and very soon in many countries VFX1 helmet was associated to Virtual Reality itself.

Design flaws

However, VFX1 had list of fatal design flaws caused by its early production – this includes ISA interface VIP board, utilization of VESA which limited it to 256 colors palette, and Access Bus which pretty soon was out of the game in favor to USB.

To overcome some of the flaws, Forte released “Linkbox”, which allow VFX1 connection to regular VGA outputs, but linkboxes were made in very small quantities, and nearly impossible to find nowadays. Also linkbox provided to VFX1 only video signal, without tracking, which make it pretty useless. Rumored full-feature linkbox were never created.

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Linkbox photo by Kevin Mellot

As possible schema to run VFX1 on modern systems – is to use old host PC with VIP card installed, provide video signal to it through video capture card (some old TV tuner), and using Forte VFX1 SDK (which is available) to program VRPN drivers to get tracking info via network.

Instead of conclusion – followers VFX-3D, VR920, and…

After releasing VFX1, Forte was renamed to IIS, and in 1998 they released VFX3D – successor to VFX1. Fully copied external helmet design, VFX3D get rid of ISA VIP card, instead it had control box, with regular VGA connection to PC. Instead of using Access Bus to carry tracking data – VFX3D sent tracking data via COM port, which became obsolete nowadays too. VFX3D doubled the resolution of VFX1 (360k subpixels instead of 180k), had better color reproduction, but had much lesser FOV (35 degree instead of 45 in VFX1) and fixed optics. VFX3D also lacked Cyberpuck, which is on my opinion – a step back. Even with overall better characteristics and compatibility, VFX3D were sold in lesser quantities.

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Years later IIS changed name to Icuiti, and focused on manufacturing compact video-glasses. However they designed a new gaming HMD, which working title was X-Viewer, afterwards changed to VR920. Before releasing VR920 in 2007 company changed its name again to Vuzix.

Vuzix VR920 – almost tripled resolution of VFX3D (now it’s 920k subpixels, which is true 640×480 resolution), and completely changed its visual design to look like slim futuristic glasses which you can put in a pocket. VR920 have built-in 3DOF head-tracker, and can be connected to VGA or DVI with included adaptor. It supports input resolutions up to 1024 x 768, and drives power, audio, microphone, tracker, and stereo sync-signal via USB. VR920 have no control box, which make it pretty possible to use as mobile HMD for small PC’s or Netbooks. Latest software update for VR920 enables all its functions on Windows7 64bit OS.

Currently Vuzix focused on multi-purpose Wrap series of portable video-glasses which lacks head-tracking for VR gaming. Wrap 6DOF head-tracking module is announced but yet not produced by company.

Teardown – Virtual Research V6

1995 brought us the V6 head mounted display from Virtual Research, the successor to the excellent design of the VR-4. The V6 doubled the overall resolution while retaining the great optics, field of view, comfort, and ease of use originally found in the VR-4. In addition to improved image quality, the V6 refined many of the mechanical elements pioneered in the VR-4, greatly simplifying these mechanical elements. The VR-4 had quite a number of circuit boards inside the helmet, but the control box could have been built completely from Radio Shack components. The V6 moved almost all the electronics into the control box, leaving the helmet with a minimum of electronics.

The V6 manufacturing process did not require any expensive tooling, such as injection molds. The plastic parts are either thermoformed or milled in a machine shop. The metal parts are either stock or machine shop fabricated. Great for short and medium run products! The VR-4 used extremely thin thermoform plastic for light blocks and circuit board mounts. This plastic tended to crack and break off over time. The V6 totally eliminates this thin plastic and uses sheet metal (anodized aluminum) and milled plastic instead.

The V6 was followed shortly by the V8, again doubling the resolution. The V6 and V8 share the same control box, power supply, and mechanical components. The V8 adds a small fan inside the helmet shell to cool the electronics and LCDs. The displays and driving electronics are from Epson.

Specs in the brochure…

3D Photo Tools

If you’ve been into 3D still photos for a while, no doubt you’ve come to love StereoPhoto Maker, a great (free) Windows based tool for aligning, cropping, correcting and adjusting 3D digital pictures. But when you’re done fooling with the pixels, how can you share them with the world? Everybody seems to have a different 3D viewing system.

Not long ago, I ran across Phereo.com, a new (free) 3D photo sharing site (think Flickr, but for stereoscopic images.) You can upload stereoscopic photos in a variety of formats, and then anyone can view them in a wide selection (their selection) of formats and sizes.

Phereo is still in public beta testing, but they’ve said that it comes out of beta on Nov. 1. Looks like it’s hosted on Amazon EC2, so I assume there’s plenty of storage and horsepower to back it up.

Phereo 3D images can be embedded in your own web pages. That alone got me wound up enough to write and publish 3D Pix, a WordPress plugin which handles all the embedding work and upgrades the WordPress post editor with an “Insert 3D Pix” button to make posting super simple.

All these photos were shot with my Fuji W3 at 10 megapixels per eye, but the W3 is the subject of another (forthcoming) post. Until then….