...So I'm just at the point where I'm trying to integrate head tracking into the system. Got a bunch of code written to pass tracker data through my system and into GlovePie and I'm ready to test it. I fire up my Vuzix 920VR and start GlovePie and POW! I get the old "Vuzix hardware is no longer supported due to them banning me....yada yada. please help me show those mean old meanies at Vuzix that they should not do bad things to me..." message.

I would be ok with it if he was trying to protect some kind of property rights or something legitimate, but holding everybody hostage because of a pissing match is just stupid. Here I am trying to do some legitimate research for the good of the community, and now I have to waste my time going back and writing my own emulation software because Kenner got his feelings hurt. Thanks Karl. You are a child.

I agree, but Vuzix is being just as bad. They should just unban him already.

Supposedly the next version of GlovePIE will remove the restriction on Vuzix products. But I agree, the whole thing is stupid.

brantlew: You can try using my software for mouse emulation, should work with 920VR no problem: viewtopic.php?f=120&t=13801

Thanks, but I would need the source code. I can't use separate tools for head orientation and position because the calculations sort of depend on each other and need to be synchronized. The emulation is pretty straight forward and I'm about 1/3 through it. I was just annoyed that I had to do now. It's a feature I was going to add anyways - just not this early.

Believe me, I hear that. Because of the GlovePIE/Vuzix war, I had to code support for the Vuzix tracker (which was pretty easy) and then also for the Wiimote (which I wasn't expecting). It was fun, but an unexpected annoyance.

Have you checked that ?

Scalable Optical Tracking - A Practical Low-Cost Solution for Large Virtual Environments

http://research.edm.uhasselt.be/~smaese ... tions.html

Interesting. The advantages of the system are that the positional accuracy is the same everywhere because the light source is always a constant distance from you and also the simplicity of it (rope lighting is cheap and simple to work with). However it seems a bit of an information overkill. I would think you could do almost as well with 1/10 or maybe 1/100 the number of light sources if they were a bit brighter.

I have considered something similar to this approach - mounting the camera on the head and positioning lights horizontally in the environment instead of the other way around. There are some significant advantages to it in terms of setup and calibration, but there are also some disadvantages with reliability and scalability. It's difficult to judge which is the superior approach without some field testing. I am hoping by the end of January I will have a better feel for it.

Nice to see you are also interested in wide area tracking. I'm the author of the paper Scalable Optical Tracking. The system could work with less led lights, it just requires the detection of 2 sets of parallel lines. So when working with LEDs, at least 3 lines are needed and the distance between LEDs needs to be at most half the distance between the lines.
A bigger issue is the lack of global positioning. So if you lose line-of sight, move and continue tracking, the system does not detect any movement bigger than the distance between lines.

I'm currently working on a spatial coding scheme to encode the global position. The system loses the indefinitely scalability, but dependent on the code length it could encode entire football fields.

However this system requires some kind of ceiling to mount the LEDs. Putting them on the ground could work, but it becomes a tripping hazard.
I'm interested what tracking solution you're going to chose for your system.

Steven

@smaesen: Hi. Good to have an academic with experience in this area to bounce ideas with and for advice.



I have an open mind right now as to how I am going to implement. Since this is targeted for a consumer-grade gaming system I don't need sub-centimeter positioning, so I have a lot of freedom with regards to technology. I will almost certainly be using a combination of optical and inertial systems. The inertial system will be for head-tracking and potentially for fine local motion. The optical system will track low resolution absolute position and is necessary to correct errors in the inertial system, to enforce real-world boundaries, and to implement redirected player movement.

Right now I don't know if the best place for the camera is mounted at a high vantage point viewing the player or mounted on the players head like your system. There are tradeoffs in accuracy, scalability, and convenience that I need to investigate. Mounting a camera on a pole requires bulky equipment and a lot more calibration - compounded by the number of additional cameras. However once calibrated the system is very simple, reliable, and scales easier.

Mounting on the head seems like it can simplify the setup. I was thinking of using some type of optical markers placed around the playing area (lights in a known triangular configuration) that when visible could be used to deduce the global position. (is that what you refer to as "spatial coding scheme"?) That would simplify the setup and calibration a lot but would not be as reliable since there would be "blind-spots". Also to enlarge the area would require enlarging the markers and/or increasing the number of markers so there are scalability problems.

Anyway these are just my speculations and ramblings for now. Like I said, I'm hoping that some field testing will give me some guidance. Maybe you have some opinions on this since you have some practical experience with it?

It's a good idea to combine the optical and inertial tracking systems to get both local and global tracking. As you will notice, your inertial system will drift over time. To correct this, you can use the less accurate optical tracking to merge those 2 streams together. But care must be taken not to introduce too much jitter from the inaccuracies of the global tracker.
To correct for inertial drift of the orientation, u need to use a sensor with a compass to correct. Else it will be difficult to redirect someone if you're not certain which direction he is facing.

Maybe a good question to ask yourself is: do you want a system to be used outside or inside. Outside you have more space, but cameras have it more difficult due to the sun and other visual distractions. It also restricts your control of the environment (no ceiling , bumby ground, obstacles, sun, weather, ...). But inside you lack the space to move freely, unless you live in a castle .

Outside cameras looking in is a good way to get a global position. But as you said, it has problems with scalability. Accuracy drops linear the farther you move from the camera. Resolution from the tracking space can be easily calculated with the resolution of the camera, FOV of the lens and distance to the camera (Pythagoras). Also what you need to take into account is the processing for the global position needs to be done as close as possible to the camera (to decrease latency) and then sent wirelesly to the gamer.

Alternatively, camera mounted on the gamer gives you a good global orientation as well as a global position (if the distance to the global markers is kept limited as in my paper). But it needs to see enough markers in each frame to get an accurate result. In an open field, this could be a problem. You're indeed correct that you need to scale the markers with your environment as a single triangle can not be seen from every position. Therefor you need to encode the global position into these markers so that when you view a subset of them, you still can tell where you are (so ID each marker in some way, like spatially or by blinking in a pattern). That's what I meant with the coding scheme.

I'm also rambling about tracking because there is just so much to tell But field testing it will certainly give you a better insight. Try to define your problem or setup a bit more so you can experiment more directly.

PS: also cbwan can give you a lot of advice on good cheap hardware and DIY VR setups. You probably know his webblog 'VR Geeks'.

Thanks for the advice. Its good to have an expert's input.

Right now I am targeting an outside environment, because I just don't think that a natural motion system can be accomplished well within the constraints of everyday structures. A gymnasium could be an exception but for most people, outside areas are more readily available. In my mind, the key to the system is redirected motion. If the player can operate for extended lengths of time without crossing a boundary then the system is useful - otherwise its just a tech demo. Learning the limits of this technique is my main area of interest. Unfortunately I have to build up a lot of support technology before I can even start that part of the project.

For the Global position, if using the rope lights, could you use two rows of 4 lights in a corner of the square to determine the position.
With 4 lights, you can mark the position within a 16*16 grid.
The reason I say a corner is so that you can tell the direction you are facing too.

The other option is to blank out some of the lights in each sector of the lights:

o_o_o_o_ooooo|o_o_o_oooooo|o_o_ooo_ooooo etc

You could indeed add coding lights to every square in the grid. But it adds more lights to place, to process and buy. Also with 4 lights you can only encode 16 places, so a 4 by 4 grid


That was indeed an other coding system I considered. In the end I reduced the number of LEDs even more by stepping of the idea of a grid and just used coded (on/off) parallel lines in 1 direction. Also turns out that using only 1 color speeds up detection by a factor of 10. I'm still working out the details and hoping to test my new tracking system in the near future.

Yes, but two rows of four lights would be 16*16.

I'm sruprised someone hasn't just hacked this exclusion out of GlovePIE. Unless he's put some effort into protecting it, you can probably just NOOP out the instructions that do the check...

Project Update:

I'm about a month behind where I thought I'd be by now because of the holidays and having to write a mouse emulator, but I'm back on track now and hit a major milestone tonight. I finally was able to scale up the system and physically walk around SkyRim in my backyard!

I need to qualify that sentence because it sounds a lot better than it actually was. I was confined to a very small 15' x 15' area (maybe double that area in-game) and there were a ton of calibration problems so I had to strictly regulate my walking speed and keep my head still while walking, etc.., but even so - the basic mechanics did actually work properly. I could look around, turn, walk forward and backward, strafe, walk forward with my head turned sideways. Everything was translated into the correct game motions - and for a few brief moments it was sort of surreal.

However the numerous bugs and calibration problems kept it from being very immersive. Here are some major problems that I identified.

1. Numerous calibration and calculation issues. Most of these were already known, but I have been plowing ahead without fixing them because I wanted to get to this milestone quickly. Now I can go back and clean up.

2. I rigged a quick 6-LED light source together and didn't bother to improve the emission FOV so the camera would lose sight of me quite often. One thing that I learned from the experience is how problematic head motion is going to be for the LED camera because it tends to move the light into an edge on orientation. Also looking way up or down occludes the light with your head. I definitely need to create a very diffuse light source.

3. A fundamental problem is the total "disconnect" between your real life walking speed and the character speed. All the subtle speed variations that you tend to make are completely lost and translated into a binary "stop" or "go" speed. That is a major inhibitor to the feeling of immersiveness and is potentially a deal-breaker for the whole idea - at least for generic gaming.

You took a brief step forward in time. That feeling of being in the world is what people of the future will constantly experience.

Branntlew... thats pretty awesome man. KUDOS to you!

Physically walking being transfered into a digital world is pretty sweet stuff. I think Omni Directional Treadmills are the way to go for this type of tech. Once they become more compact ofcoarse.

Sure, probably wouldn't be that hard, but if someone did that, and released it publicly, we might just end up with all 3d devices banned.



Heh, Strange, isn't it

Thanks for the encouragement guys. It helps keep me motivated on a long project like this.

@Moggle69: Omni-devices are cool but I don't think they are very realistic for the average guy. It's bad enough we have to drop over $500 on an HMD, but adding in a piece of equipment that would easily cost over $5K is too much to ask of all but the most die-hard guys. A natural motion tracking system could potentially cost less than $200 and provide a superior experience than any omni-device! So from a pure "value" perspective I think some type of tracked natural motion system (whether Kinect or something like mine) is a clear winner. If you want to experience VR movement anytime soon (outside of CES demos) then this may be the only option.



I've been thinking about problem #3 a bit and I think maybe using the 360 controller interface instead of WASD keys would help a lot. The 360 controller provides continuously variable character speed and direction - true? Unfortunately since GlovePie 0.45 STLL doesn't support Vuzix I'm going to have to implement yet another device emulator if I want to test that. Aaargh! (or get a different HMD )

I hear ya.... my only question is, how do we fix the barrier issue?

Lets say you have an empty 200sqft room. You start in the center of the room, put your HMD on and start playing. What is going to prevent us from walking into the wall?

I thought it was Vuzix that had banned Carl Kenner, but I see in the documentation.rtf for GlovePIE it seems to have been 3Dmtbs.com that banned him?



Is this old or something? Or has he been banned from heaps of places for some reason?

Are you quoting Carl Kenner? Is he banned from MTBS?

I suggest you take a look at this thread: viewtopic.php?f=120&t=13784

As for avoiding hitting the walls, the answer is re-directed walking. You will find some stuff in that thread, I believe.

There's also a good bit of discussion of redirected walking throughout this thread.

@brantlew: Awesome work man! Seems to be coming along nicely. If you need some help getting the Vuzix tracker to work, I may be able to provide some code to get you started. Just PM me.


If he's banned from MTBS, I may be able to reverse that. But from what I understand, he was banned from the Vuzix forums.

Thanks Cyber. I'm using the Vuzix tracker now which is why I'm having the issue with GlovePie. CyberVillain is working on the Sparkfun driver and I have high hopes for that little piece of hardware. However since I only have a Vuzix HMD I will continue to have GlovePie woes (sigh)

Eugh! CarlKenner again?!?

With respect, we aren't bringing him back. We haven't banned someone from this forum in years (with the exception of spambots), and we did it because he was making an active effort to be disruptive and really bring this place down. He has political (and social) views that he felt entitled to express here at MTBS, and that's not the purpose of this site. When we politely asked him to stick to 3D and handle his inflammatory poltics elsewhere - he refused, and further blasted away in the chat window. I wasn't the one who banned him in the end - it was Sharky after Carl went on a personal tirade against him despite all his hard work on MTBS.

There is good cause for CarlKenner not to be here and other sites, and while he has undoubted expertise and passion for 3D and virtual reality, I'm not confident he could contribute to MTBS without bringing back his negativity as well. Thanks for your understanding.

Regards,
Neil

Thanks Neil, I guessed it might be something like that.

It's been a while since I updated. As usual...work, other projects, and procrastination have slowed my progress, but I've been ramping up the last week or so and have some things to report.

I spent a bunch of time in January trying to track down some calculation errors in the computed world position of the light source. I found a couple major bugs fairly quickly that reduced the error a lot, but my calculations were still off maybe 5% at certain angles. I spent some time doing tedious measurements to determine accurate FOV of the Wii camera and characterizing lens distortion. Unfortunately, I never could find the source of the problem so I gave up and moved on. I can live with the errors for now.

Recently I have been preparing for a big data-gathering push. I realized very soon after my first live walking test that my motion tracking algorithms needed a LOT of work. It's one thing to track a light source moved smoothly by your hand. It's another thing entirely to track a light bobbing around and turning on your head. All that shaking around and turning has to be subtracted and smoothed out of the signal in order to come up with a decent character motion model. So I have been modifying the software to do some field recording of sensor data during locomotion. I will use the recorded sensor data to tease out this signal and tweak the motion tracking.

But before that can happen, I need a decent light source. So this last week has been spent trying to build some type of strong omnidirectional light source on my head. Basically I made a three sided pyramid on a pedestal and wired 6 LED's per face. The whole thing is then attached to a pair of headphones. This way the LED's sit right on top of my head and point directly back at the camera. Maybe I should have created a 4-sided pyramid but I only ordered 3 LED modules a few months ago and was working with what I had. Anyway, my hope is that the edges of the pyramids can still be detected. I wanted to encase and diffuse the whole thing in a ping pong ball, but I think it's going to be too big for that. Anybody got any bright ideas of how I can create a diffuser?

So here is a pic of my first prototype. I still need to finish the wiring and soldering but you can see the structural design.



I am eager to do some range testing (it needs to be detectable at about 100ft (30m)) and then get my data gathering underway. Unfortunately I broke one of my LED modules during construction so will have to wait until a replacement part comes in. I'll post of pic of the completed unit and give a performance update pretty soon.

Update: Well after digging around I found this thing that will hopefully work well as a diffuser (and also make me look even dorkier )



http://www.twistncflcovers.com/item/basic-product-line/round-cfl-cover-and-snap-base/lid=16049527

Nice work. Am eager to see where this goes.

I have also made a few efforts to create a diffuse LED light source.

Method #1; Apply transparent "disappearing" cellophane tape. Moderate diffusion, but easy to add more and it seems to be more even than my other method.

Method #2; Grind the top of the LED to change its shape. The next step, I didn't try since I didn't have one, but a friend used a buffer to smooth its shape and make it more transparent. However, the results were not an even spread of light.

Method #3; bend the LED's different directions. However, in your case, since they are pre-made modules, they may not have allowed for enough space between the LED and the circuit board.

Joe Dunfee

@Joe: Luckily I found pre-built modules with "wide" angle (50 degree) LEDs, so they spread pretty well to begin with. Just to be sure I went ahead and clipped the tips of them as I have heard anecdotal evidence that it increases the angle. However, subjectively I really can't tell the difference - plus that's how I broke one of them. Aaargh!

Interesting tip about the tape. Would you use the "satin" looking kind instead of the clear? And you just stick it right on top of each LED? Simple. That worked well for you?

Yes, the satin type. Of course, keep in mind that it would cut the output somewhat.

I just stuck it on top of the LED. Though, I imagine there might be some way to do it more professionally. The tape stuck onto a curved surface does not look that good. Perhaps on the flat snipped-off ones it would do OK.

Joe Dunfee

Maybe you could try a cylinder out of very thin paper or mate foil. Maybe you could wrinkle it in the pyramid base form to preserve trackability.

Exaple of the paper I mean:
http://www.pss-treff.de/bauen/mig3/butterbrotpapier.jpg

In germany we call it "Butterbrotpapier" which translates to "Butter-Bread paper" it is used to wrap up lunches etc. its quite thin as you can see in the picture.

That's a good idea.

An extension to that idea would be to take the thin paper, wrap it around a balloon, use a clear glue to harden it, and then pop the balloon to create a stiff sphere of thin paper. (paper mache I believe it's called) It could have very good diffusion properties, but it would also be fragile.

yeah that is pap mache. The problem is that you only can use one layer of paper, normaly you user several layers of toilet paper.
but its easy to try since that kid of paper is sold in 10m rolls in every supermarket for nearly nothing.

an alternative would be frosted plexiglass:
http://www.estreetplastics.com/Frosted_ ... _s/142.htm
That would certanly give more stability. Also you can bend it with hot air, but you have to be carefull with that xD
I can't say for shure if the frosted status survives the bending, I only worked with clear material.

You can buy frosted window film for pretty cheap, its basically a big decal that fakes the frosted glass look. They have them at my office, they are fairly cheap.

For example:



http://www.purlfrost.com/purlfrost.php

A lot of good suggestions.

I ordered that bulb cover because it's cheap, durable, and requires no construction. But if that doesn't work, I will consider all of these options.

Thought i'd already said this, but can't you get the same effect as frosting by lightly sanding the LED's?