mrfahrenheit94's Budget HMD

[mrfahrenheit94]

Hi,
So I wanted to venture into the world of virtual reality and HMDs, but as a college student, money is not abundant.
A little about me: I learned about HMDs mainly through google searches and this forum (thanks!) and I think the most useful page that I came across was the one on vrtifacts.com called "LEEP on the Cheap" which shows how you can make LEEP style optics for a small amount of money.

LEEP optics are known for their large FOV, but because they were invented in the 80's, there weren't very high resolution displays to accompany the optics thus making the overall image quality kinda bad. Well, we're not in the 80's anymore, and I am a proud owner of the Motorola Atrix, which boasts a qHD 960x540 resolution, all in a compact 4" display. So I decided to go with that for my screen.

The first thing that I purchased were the lenses. The article on vrtifacts helped a lot when it came down to which lenses to buy. I ended up buying 32.5mm diameter plano convex lenses with a focal length of 85mm. The lenses themselves were only $11 for two, but shipping was another $11, so yeah, $22 for the lenses.

I received the lenses yesterday in the mail, and decided to play around with them. I held one lens up to my eye and adjusted the distance to the display until it became sharp. It was freaking awesome. I didn't do any calculations, but the FOV was definitely more than 60 degrees. It reminded me of an IMAX theater. The greatest part though is that although I could see individual pixels, it was a lot less noticeable than I expected it to be and the experience was so immersive that I didn't really notice.

A problem that I did notice though is that it is blurry on the corners of the display. This is due to the fact that the screen is 4". If it were say a 3" screen, it would have been better, but I didn't mind it that much.

A much bigger problem occured when I tried using both lenses at once with the same display. When there is a single object on the screen, the lenses cause the left eye to see that object shifted to the left and the right eye to see that object shifted to the right. This resulted in unwatchable 2d fullscreen videos, UNLESS I angled the lenses inward towards the screen.

The easiest solution would be to get a 2nd display and center each display on the center of each lens, but due to the size of the screen, that would be impossible because the average distance between the eyes is about 65mm. The solution to the big display problem is to make the two screens angled into a "V" shape.

So after playing around with the lenses, I made a very ugly cardboard cutout to fit the lenses and display into. The final design actually takes advantage of a plastic PSP case that seems perfect for an HMD. I modeled a 3d version of what the final HMD should look like, but it is a WIP.

Here's an exploded view of the HMD modeled in Autodesk Inventor

http://www.youtube.com/watch?v=ETZ8CgVP4nM" onclick="window.open(this.href);return false;

I was initially just going to make this a monoscopic HMD, but then my friend came up with an awesome idea: Use the side-by-side 3d method with videos and games. And it works! The geometry of the lenses happens to work out so that when looking through both lenses, I can see the left image only with my left eye and the right image only with the right eye. I tested this out with some 3d youtube videos and some of the side by side pictures on this site's homepage.

The obvious downside of the side-by-side 3d method is that it cuts the horizontal resolution in half, but it works, so I'm happy.

Here's the big question though: How am I supposed to play PC games in 3d on my phone if its a PHONE? Well, there just so happens to be an app available called Splashtop Remote which is a VNC server of sorts, but with a very high FPS. I say very high RELATIVE to standard VNC programs that run on the phone. The standard ones usually get 1fps. Yes, ONE. Splashtop gets about 15-20, which I know isn't spectacular, but it works. For those who don't know, the app mirrors whatever is visible on the monitor of the computer running the server program. So its basically a remote display.

So I downloaded the iz3d driver and set it to side by side mode, fired up Left 4 Dead, and BAM my homemade HMD was working in stereoscopic 3D.

More pics and videos to arrive soon.

Questions, opinions, etc.? Sorry for such a long post.

[Fredz]

It looks basically like the My3D for the iPhone to me, except the FOV is probably much larger. How did you handle the image deformations due to the LEEP optics ?

[cybereality]

Interesting. This sounds like an amazing project, especially if you can play PC games. I'd like to see some photos of the setup.

Also, I didn't realize the optics could be that cheap. I should pick up a pair for myself.

[Johnny-Mnemonic]

Please, could you post some more pictures of the outsides and insides of your HMD.
20 FPS could be ok, especially if we are talking about homemade wireless wide-FOV stereo HMD!

[Synexious]

20fps isn't enough for me.

[Johnny-Mnemonic]

20fps isn't enough for me.

We're discussing experimental stuff, even if I prefer at least full 60 too.
Anyway if optical/structural design is good enough, you can put wired LCD panel there, and use it as regular monitor.

[Synexious]

I prefer 60 as well, but even for experimental setups, I require at least 30. 20 is quite simply too low for me.

[mrfahrenheit94]

Ok, so an update:

With one eye and one lens looking at one display, it was a wide FOV. It ends up not being as spectacular with two eyes, two lenses, but still one display. I mean, yeah it is awesome, but ideally there would have to be two displays. Also, this is with a very cheap cardboard box, so I wasn't taking advantage of the whole lens, etc, so there should be a lot of improvement when it comes down to the final design. I did try out some 3d videos, side by side method, downloaded with youtube, and it works. And in those cases it is plenty more than 20fps. There isn't much distortion at all around the corners, mainly because the display doesn't fill the entire viewable area through the lenses. When I tried mounting it to my head with the arms of the RealD glasses, it didn't work, so I ended up using a very convenient LED Headlight strap to hold it to my face. And, yes it is pathetic, with the cardboard and all, but this was just a quick test to see if this was possible. THE FINAL DESIGN WILL NOT BE MADE OUT OF CARDBOARD. Thank you, haha.

On another note, the software that I am running on my Atrix is called Splashtop Remote. The company released an HD version for tablets called Splashtop Remote HD, which is advertised as having 30+fps, higher resolution, and is optimized for Tegra 2 chips. Well, the Atrix has the Tegra 2 chip, so I contacted them about being able to use the HD version on my phone. With that in place, PC gaming functionality should improve. I'll let you know what they say.

I'll post a video later.

[crim3]

What about with the displays in portrait layout? They may fit well then.

[Johnny-Mnemonic]

Good!
Let us know about "Splashtop Remote HD" and advances in your construction

P.S. cardboard kinda remind me this guy:

Just kidding.

[cybereality]

LOL. Nice work.

[AntiCatalyst]

Yeah, really nice work! This gives me another idea though; There should be a 6dof tracking app for Android! Many of the newer android devices have a full-on gyroscope along with the standard accelerometer, so maybe they could be used for wireless gun or head tracking.

[Tone]

Try the Cheep Leep optics (one eye) on an iPhone 4 with SkyView or any of the accelerometer enabled stargazing apps. SkyView is nice because it's an AR app that superimposes the stars and planets over the camera view. The retina display looks pretty darn good.

[mrfahrenheit94]

Yeah, really nice work! This gives me another idea though; There should be a 6dof tracking app for Android! Many of the newer android devices have a full-on gyroscope along with the standard accelerometer, so maybe they could be used for wireless gun or head tracking.

I've been looking all over for an app like that, there are a couple that emulate a computer mouse using the accelerometer and orientation sensor, but I haven't been able to successfully implement them with any game etc.

Still working though.

[crim3]

From my experience, those sensors integrating accelerometers and gyros are 3dof, not six, but are often considered 6dof sensors by mistake.

[AntiCatalyst]

Why? They can track along 3 axes of movement and 3 axes of rotation. Depending on their accuracy, they should be able to pinpoint a relative
location and rotation in a 3d environment. What else can a 6dof tracker track? Or are they camera-based? A camera gives an absolute position/rotation instead of just calculated relative ones that probably would go out of sync after a while. OTOH, a relative tracker has an infinite range of where it works, while a camera-based system cannot be used outside the working range of the camera. So if there was a life-sized AR sim or game where you'd walk on real streets like Layar, you'd need a relative gun tracker Or just in an environment that's too big for a camera system.

[crim3]

It could be done, but not with enough accuracy to be useful. The accelermoters are placed there with the purpose of reading the gravity field, and they are good enough to do just that. To accurately integrate a linear position the accelerometers must be in another order of quality and price and output data at very high frequency.

[Okta]

Great ingenuity with the phone and streaming app idea. I wish there was a trial version to give it a try with.
Can Splashtop remote handle 2 clients? Maybe 2 android phones/tablets side by side with some prism lenses

[PalmerTech]

The image is squashed side by side, not the correct aspect ratio, correct?

If so, that seems like a small quibble, but the rest of the concept is very cool!

[mrfahrenheit94]

And I have returned, after being dormant for a while, kinda busy with college, sorry. But I've had a little down time on my hands so I made some progress. It just so happens to be that there is a 3d printer that is readily available for use at my college, so I took advantage of that and 3d printed a frame for the lenses, which looks quite awesome. The lenses fit perfectly, and I used the LED headlamp strap to hold it on my head. Quite comfy. Anyway, I'm going back to the lab today to print the mounting brackets to attach to the phone-side of the HMD.

Also, great progress with the software, because I successfully reverse-tethered my phone! That doesn't really sound important but it is really crucial in getting the best visual experience. This is because the Splashtop Remote software (the software that streams whatever is on my computer to my phone, the display) ideally runs on wifi, which is fine, but there will be a delay and the transfer rate of the video won't be the highest when it is sent to the phone. Well, reverse tethering is a means by which you can connect your phone to the internet using your computer's internet connection. This is great because that means that I have a direct USB connection with my computer that will stream directly and locally to my phone all of the information that Splashtop Remote sends. Essentially, there is no delay, and the quality of the video is the highest possible. The obvious downside is that you now have to be wired to a computer, but I think this is more or less temporary for the time being.

Oh, and Okta, there is actually a trial version of splashtop remote for android phones (I think for iphone as well, but I don't have one so I couldn't tell you.) Also, the PC client is free to download as well.

So yeah, I'll try and update more frequently now.

Adios