Back from the dead

I seem to have not posted anything on here forever. Surprisingly, visitors are still coming to this blog and are contacting me for information about my setup. If you have any questions, I’m more than happy to answer them for you. If you want a fast reply, I recommend you e-mail me on the address provided on the contact page.

As far as the project-status goes; I have been too busy with other things to really invest a lot of time in it. I have made some progress with trying different band- and highpass filters, which I’ll hopefully be able to write a quick post about sometime in the near future.

Unfortunately I busted the LCD panel inside my table, since I was forced to continuously remove it and then put it back in. This caused some lines of dead pixels all the way down the screen, which sucks. So for all the people out there trying to build a similar setup; don’t drop the panel in until you’re very sure you won’t have to take it out again, or actually come up with a system that allows easy removal without having to gut half your setup everytime it needs to come out.

Stay tuned for more.

Software: Crayon Physics

I graduated this week with my table! Below I have a short video of the software I was running. Big thanks to Mark van Rees for helping me out with the software, I wouldn’t have made it without him. It’s a modification of the open source Crayon Physics by the guys at multitouch-barcelona.com

I built an LLP LCD table, but unfortunately due to some filter problems I wasn’t able to run the application on the built in LCD matrix. That’s why this recording was made off my laptop screen. All the interaction is being done on the table, though.

I ordered a new bandpass filter today that should fix the above problem. I’ll upload some pictures of my finished (and painted) table. Stay tuned!

Table body built

Yesterday I finally built the body of my table. Before continuing this post, I would like to give many thanks to my dad Theo for helping me out tons with building the body of the table. Thanks to his experience in woodworking it was done in no time and the design came out great.

Thanks Theo!

So, let’s continue with some pictures:

Here’s the table loosely mocked up, no screws or glue yet!

Here the main “box” is put together. One side is left out for now because it will have to function as a door in the final design, so it’s eays for me to get inside and adjust things. Now, let’s get started on the complicated stuff; the table top.

You might remember this table top I put together a while ago. It was fine at the time, but now it needs a lot of adjustment to house the lasers safely, holding the LCD matrix and of course.. the acrylic.

In order to make the tabletop more compact, I decided to rip off the IR LED’s that I put in back when this table was meant to be an FTIR table. It wasn’t pleasant to do, but it’s for a good cause.

To put a neat frame around the LCD matrix that could hold the acrylic at the same time, we went with 4mm MDF and cut out a hole in the middle. The matrix will be suspended below this frame, the acrylic will be put on top of it. Here it is cut to fit the hole in the tabletop.

After cutting the hole in the frame, it was time to think about how to house the lasers. Now that I took my LED’s and aluminum frame off the acrylic, it was lowered substantially. In order to get the lasers levelled out with the acrylic, we decided to take out a part of the tabletop frame and put the lasers in there. Unfortunately the tabletop was partially glued so it took some violence to cut out these middle pieces.

Because of the force we had to use, the surface became a little uneven. To fix this, we mounted 6mm MDF squares in the holes, evening them out nicely. Now the lasers should be about level with the acrylic, and with eachother.

Next it was time to build the protective cover that will cover up all the electronics, and will make sure that no laser light can escape. It’s build from 2 layers, in the above picture is the 1st (bottom) layer. It’s 6mm MDF. The shapes that are cut out of it correspond with the holes that were cut for the lasers, and the 120 degree angle lenses that the laser have. This way the lasers can sit in the holes that were cut earlier and disperse their light at a maximum angle over the surface. The lasers are 12mm in diameter, and since the whole (with the MDF mounted in it) is 6mm deep, and the protective cover is also 6mm thick, it’s an exact fit.

Before putting on the top cover, there were some other small things to do. We mounted a small block on both sides of the tabletop, as can be seen in the picture. This block has two functions: it keeps the LCD matrix in it’s place once it’s sitting in the frame, and it support the thin (4mm) MDF frame that covers up the edges of the matrix and holds the acrylic. Simple, but effective.

Here we’re putting together the top cover. It will actually slide over the table as a sort of shoebox lid; the top two layers will be attached to piece of wood on the side, made to fit exactly over the box. Once you see the end results hopefully it will become clear what I mean.

Here’s the complete lid being held together by clamps. As you can see it has a rim around the edge that will slide neatly over the box. On top of that is the layer with the cutouts that will house the lasers, covered up by another layer featuring a wide rim that users can rest their arms on or put their stuff on. The whole thing put together is a very safe LLP setup, because no matter what happens, users can’t possibly get laser light into their eyes, not even if the lasers would somehow turn!

Here we’re putting in the crossbeams that will hold the “door”. The door will be attached with two magnets.

This is the final table, with the acrylic mounted in already. If you look at the enlarged version you can see the sandwich construction in there. Once the matrix is mounted though, all of this will become invisible and the screen will simply look black.

Later on this week I will paint the table and drop in the electronics. I’m not expecting this to be too much work. Stay tuned for more!

Materials for the body

I bought all the materials for my table yesterday, and I’ll be putting it together upcoming Sunday. Stay tuned for pictures of the final table.

The lasers work

I haven’t posted in a while, mainly because I’ve been writing my paper and been busy with my day job. Just wanted to write a quick post about my laser test I did today; I don’t have my protection goggles yet, so I can’t mount or tweak them yet, but I decided that I needed to check if the lasers even worked or not, since some people have been having some trouble with the Aixiz lasers. So, I made a temporary setup that in no way allowed me to look into the laser. And, well, they work. They’re not quite invisible, since 780nM is just on the edge of the visible spectrum, so they emit a light red glow. But that’s okay, in a well lit room you can hardly see it at all.

Hopefully I’ll be able to get my goggles soon so I can mount them and finish my hardware. It’s about time the software gets made. Stay tuned for more.

Just got my lasers in the mail

My lasers came in the mail just now, together with the line lenses:

Now I just need to get a power supply for them, which I’ll probably do somewhere next week, and then I can put them to the test!

LCD matrix issues solved

Today I went out and bought some caulk paper to use as an alternative diffuser in my LCD screen. The original one didn’t let IR light through, so it had to go. But in taking that diffuser out, I exposed a honeycomb screen that is embedded in an essential layer in the screen that I can’t take out. So I had to find a different diffuser, and several people suggested I use caulk paper (tracing paper), which is also used by a lot of people to project onto.

Unfortunately they didn’t have the right size paper for my screen, So I had to use one piece and then a little slice of another sheet to fill up the entire screen. This results in a thin (barely visible) vertical line on the screen, but for now it’ll do. When they get the bigger sizes paper in, I’ll just replace it.

The other problem I was having with the screen was that it seemed to be giving off a crapload of IR light, hence showing up like a bright white rectangle in TouchLib. After fiddling around with the settings a lot, I managed to get settings that pretty much solve this, and still managed to pick up blobs from the TV remote. I hope this means I’ll also be able to pick up blobs from my lasers (which haven’t arrived yet).

Still, I find it weird that my screen gives off so much IR, since the backlights in there should be TL which doesn’t give off any IR. Granted, the lights do get quite hot, but there’s a very uniform slab of IR light which I can’t imagine is being caused by heat..

Here’s a photo:

You can clearly see the white rectangle (this is an image of the matrix hanging over the edge of the table slightly, with the camera sitting on the floor. That’s why you only see a small strip of the matrix in TouchLib), but with the right settings I was able to fix it mostly. If someone could enlighten me on what’s going on here, that’d be great though, because as far as I can see that is IR light, right?

Well, I suppose next is finding an efficient to mount the matrix and the layers, and then start running some software on this thing.

Stay tuned for more.

Built the tabletop and took apart my LCD screen

Today I got a lot of work done. First I put together my tabletop (without finish or cover, so it still looks rough), and after that I took apart the 22″ LCD screen that came in today. Both things went fairly succesful, apart from some issues with the LCD that still need solving.

Let’s start with the tabletop:

As seen in my previous sketches, I wanted to make a frame that the acrylic could “sit” in. That’s exactly what I did.

 

Here’s a closer view on the edge that the acrylic will sit on. I only made these edges on the long sides of the screen, so that the wires that connect the LED’s to their power source have a small gap to go through on the short sides.

 

Here’s the last part put in. I glued everything together and let it cure for a while, and afterwards I put in a couple of screws at each intersection to make sure that everything was secure. I don’t want people falling through my table when they lean on it a bit. (-:

Here’s the finished thing with the acrylic sitting in it. Note how the wires fit through the small gaps I left on the short sides.

While putting this thing together, my screen arrived:

I have to say it was pretty weird to take a brand new, beautiful, and most important bigger than the one I actually use as a normal screen, and start prying it open straight away.

After prying open the case (which was quite a puzzle), it looked something like this:

So far so good. Then it was time to open it up and see if there were any FCC issues (according to the list it doesn’t have any FCC issues, but I had to see it to believe it)

 

Note the flat data cable on the top; that’s the cable that will transfer image data to the matrix. Judging from what I could see here, it was long enough for my purposes.

This is what it looked like after taking off the top “box”. This box contains the on/off switch, the power control unit and the graphic control unit (can’t be arsed to find out what the official terms for those are).

I took off the metal cover (which contains the backlight and the diffusing layers and whatnot), and there was my matrix!

This is the other half; the backlight and the diffusing layers.

It’s very bright when turned on.

This is what’s left of the whole thing after taking the controllers out of the metal casing and removing some of the diffusing layers so that the “sandwich” becomes transparent to IR light.

Here it is, switched on and attached to my laptop. Luckily everything still works; I was sweating it a bit when I turned it on.

And here it is again. I actually used a part that was in the screen for the layers to sit in, so that should make mounting this into my table a lot easier.

Unfortunately, I still have two issues with my matrix right now. The first is the honeycomb structure that shows up over the image. It’s embedded in the layer that diffuses the backlight into a uniform slab of light, and it became visible because I had to remove the layer that was on top of this, since it blocked almost all my IR light.

The second problem is actually worse; the screen is giving off a LOT of IR light. It just shows up as a big white rectangle. Unless someone has a solution to this, it looks like I’ll have to mess around with custom backlight, something I really hoped to avoid.

So if anyone has any suggestions or even solutions to these problems, your input is very, very welcome! 

That’s it for now, stay tuned for more.

First test with visible laser

I haven’t written here in a while, but that definitely doesn’t mean I haven’t been doing anything.

After considering the pros and cons, I’ve decided to not make a compliant surface, but to go with lasers instead. The big advantage is obviously that it’s a fairly cheap solution, and that I’ll have a zero touch interface. The downside is that the IR led’s that are in there now are pretty much useless, except to maybe fill in some potential dead spots. I’m going to leave the LED’s in for now, maybe I will take them out later. If not, I’ll be the first to build a hybrid FTIR – laser LCD multitouch (which is, for the most part, a pretty useless kind of hybrid).

Here is a picture of the laser I used for my first test today. It’s a simple laser leveler with a visible red laser, so perfect for testing.

It came with a tripod, which was nice since it saved me a lot of time setting the whole thing up.

Here’s a video of what the test looked like:

Remember; this is just a test. I’m using only one laser, so if my fingers cross the same line on the screen, the last finger won’t show up since the first finger is blocking all the light. For this reason I’ll have to get a second laser, so that all fingers will be illuminated at all times.

Also, you might have noticed that the blobs seem a little “choppy”. That’s because my wiring is actually sticking out about the acrylic a little bit, so when aligning the laser to the acrylic, the wires sometimes get in the way, blocking the laser. Another good reason to remove the LED’s and wiring, I guess.

Here’s a picture of the crappy wiring:

Anyways, this system appears to be working perfectly. Zero touch and dragging work great, and the lens is creating a perfect line:

I also ran a test using the stem of a wineglass as a lens; it does work pretty well, although the line is a little thicker and not as consistent. I think it would still work for this specific purpose though.

For my table I’m going to need IR lasers rather than visible ones. At first I considered taking apart a DVD burner and taking the IR diode from that, so I could build it into the laser leveler I got. Upon further investigation I found out that it’s cheaper to order the lasers and the lenses online, so those are currently being shipped to me.

I also finally ordered my LCD screen; I should have it by upcoming Wednesday, upon which I’ll have to perform some major surgery on it. I can’t deny that I’m a little bit nervous about that. This is the screen I got:

It’s a BenQ FP222Wa 22″ inch screen, really not much else to say about it. It’s pretty cheap to order online, and I know from experience that it’s a very nice screen, and according to the list I found it doesn’t have any FCC issues, so it should work fine for my table.

And last but not least, I finally bought some wood to start constructing the frame. I’ll being doing that upcoming Wednesday and Thursday, so stay tuned for more.

Designing the frame

Today I’ve been thinking about how the acrylic should be housed inside the table frame. The problem with this is that, at this point, I don’t have my LCD matrix yet so I’m not sure on it’s properties (and hence on the way it should be mounted).

The second problem is that I’m still fiddling around with a compliant surface, and I really would love to experience with the laser approach I mentioned in earlier posts (click). More and more succesful tests are being conducted, and the lasers really look like they have a lot of potential.

So, in the design I made for now in SketchUP (getting slightly better at it now), I’ve left the matrix out for now, and I came up with a good place for the optional lasers.

(Please click for the fullsize version)

The acrylic isn’t actually in the drawing, but it will rest in the bottom part, as I’ve also noted on the design. The lasers and lenses will be mounted on the second part, so that they’re close to the surface, yet the lasers can’t escape on the side (the IR light is dangerous to your eyes; I don’t want to blind any users, since that would probably affect my grade for the worse). Then on the top I’ll have the metal cover (”traanplaat” in Dutch, I’m not sure what the English term is; Google tranlator couldn’t help me on that one) that you’ve seen in my previous sketch.

Hopefully I can get the materials for this somewhere this week, together with some old CD-ROM readers so I can play around with the lasers.

More will follow soon.