Moving home

As i mentioned in previous post we already designed the table-supporting structure and had it produced at a local shop. However there was a little problem. Although it came out pretty good visually the problem was that it is closed. And why is this a problem… well because all the pieces that have to go inside the box need some sort of micro-adjustment. And you can’t do that with a closed box. So the approach we took on that one was to build a structure with the exact same dimension but with access inside it. The solution also involved to build the base of the projector, the mirror and the cameras and test them in our test box. That was important because of the great accuracy needed espacially on the mirror and the projector angles and measurements. The build of the test box although simple in concept required careful designing and ordering of the parts. Then it was assebled at my place using a drill and some corner brackets. It wasn’t very easy to assemble all the parts but luckily after a lot of hours i got it right.

So here are the photos and the details…

A photos of the parts right before the beginning of the build process.

The top and first of the 2 frames needed for the box laying on my construction table.

After both frames where ready and inspected to check if they where aligned correctly i added legs to one of the frames. This was the most difficult part because the corner brackets that i used had the tendency to pull the leg inside the frame and that made it difficult to have it straight up ( 90 degrees angle ).

Here you see some of the legs already in place and the top frame ready to be placed on top of the other one. Trying to keep everything straight here was even more difficult than the previous step.

And here is the box ready. After screwing all the screws the box was slightly not orthogonal but after loosing some of them and tightening others helped bring the legs in the right position.

With the test box ready it is obvious that it is easier to test things inside it than in the actual box.

The next step is to add some kind of projection material on top of the box and put the camera-projector-mirror base inside the box for testing.

Also i bought a cheap wood-like sheet and painted it white to use it to close the box when it is needed. That sheet is also screwed to the sides but can easily be removed. It also helped in making the box orthogonal and more steady.

This is a picture of the sheets after i have panted them and waiting for the paint to dry… Actually there are 2 more that you can’t see in this picture.

Catch Up – Updates

Well, after a long time without updates and posts you must be wondering how the project is going. There are a lot of updates and hopefully the project is progressing and is not very far from being complete. There will be a lot of post ( about 4-5 ) with the major milestones of it. For now i ‘ll give you just a small one. The fan system.

We designed a fan system consisting of 8 large (14 cm ) fans. 4 of them are used as input and 4 as output of the air in order to establish a constant flow.

The are mounted at the lower left and right sides of the box using some custom bases that me made out of simple wood. So i wont keep you waiting , here are the photos :

Right before drilling.

Trying to get the dimensions right.

Well…drilling
In order to minimize the sound from the fans we added some rubber tape .We have done the same thing with the pc base.

Adding the rest of the fans and wiring them together.

Almost done with the first base and then we will add fans to the second one.Only the second base will have the fans placed in the other direction.

After that we just have to mount them inside the box. Well we actually did mount them but i forgot to take any pictures of it.

Fff…that was a long post. Stay tuned for the rest of the updates. Hopefully i ‘ll upload one update per day to catch up to the current state of the project.

The computer

The computer is the heart of the system. First of all we had to choose a powerful enough computer in order to handle all the required task such as the image processing for blob detection and at the same time being able to run our software.This wasnt and easy task and we had to balance between cost and performance. The main parts are a quad-core CPU and a powerful GTX 260 graphic card. Apart from that there are 4 GB of ram ,500 GB hard drive and a silent 600W power supply.

Even at the beginning it was obvious that we had to make some kind of base for all this components in order to place them inside the box. We couldn’t just put the pc as it was. This is why although the pc came in a normal case we had to remount it.

For the base we decided to create a sliding construction in order to make it easier for the pc to be placed inside the pc and taken out whenever necessary. This sliding mechanism is created by 2 aluminum U-channels bolted inside the pc and a pc of wood that slides inside them. At the back of the wood there are some special vibration absorbers to make sure there wont be any oscillation causing noises.

Here are some photos :

Testing how to place the computer components.Notice the aluminum U channels on the left and right of the wooden back.The channels are drilled so they can be screwed on the inside of the box.

and another photo of the base.

Testing where to place it…

Here are some details of the U-channels

Screwing it on the box…and it is ready.Now we have to place the rest of the components of the pc.

There was a small problem with the GPU as it was too loose due to the lack of support so we tried to support using a metallic angle and screwing it on it.

Once everything was in place we tested the pc to be sure everything was working before placing it inside the box.

Booting an Ubuntu live cd that we had lying around…

After that it was a matter of simply sliding the pc base to the screwed channels-guides and everything was ready…

Since the PC is ready we have to proceed with the rest of the construction such as the projector and mirror base. Also there is going to be a post with the cost of several parts as well as a post with some project milestones to help you follow the projects development.

The Table structure

After deciding on the design of the table and sending it to our local carpenter we have the results back!!!

First of all lets see the final design that we settled on.

It is a modular design and has also room for the legs of the users. As you can see the dimensions of the top part are quite big and therefore can’t be moved through doors as is. So the top part can be separated from the bottom in order to be moved to another room.

Well after that short introduction lets see the results…

Its amazing when something that you designed in software is seen in real life!

This is the real table placed inside the lab.We settled on an all white even though we had some alternative colour combinations.

And here are some more detailed photos :

In this photo you can see 2 things. First in the top part you can see the little step that is designed to hold and support the actual screen.In the bottom you can see the place where the 2 parts of the table can be separated.

In the above photos you can check the air vents that are going to be used to mount the fans. The fan structure will be mounted inside of the table in front of the vents.

All the equipment of the multi-touch table is going to be mounted inside of this supporting structure (cameras, projector, mirrors, leds etc).

Drawbacks

Well , i know i haven’t updated the blog for a while but we had some drawbacks concerning the table and some diffuculties sourcing the pleciglas – not to mention the exams …

First of all i have to let you know that i own you some detailed post about the table ( the wooden structure ) since we have it in the lab, as well as the pc that we have decided to use (hardware) and how we placed it inside the box.

For the drawbacks, I don’t know if I have mentioned it before but we are planing on making a dual camera setup in order to minimize the required distance the cameras need to be placed from the screen. That is also the reason why we choose a short-throw projector. After some sketches that we made concernig the projector and camera views we settled on the table dimensions that i detailed in the previous post. However due to not taking in consideration that the projector doesn’t have its lens placed in the center but near its left edge we didn’t see a small problem. The right camera has its view blocked by the right side of the projector. Therefore we had to find a solution to the problem. Again i went back to the drawing table and i came up with a few possible solutions that we have to test to determine which one will work best. They are going to be tested from the easier and cheaper ones to the ones that will require a buy of a new lens. How and if they will work has also to do with the capabilities of the open tracker that we plan on using ( CommunityCoreVision – http://ccv.nuigroup.com/ ) .

The simplest solution is to lift the cameras up to the minimum distance that is allowed by the lenses.In particular we need to lift the right camera to a height at which it wont be blocked. What we are concerned is if the right camera can be set up to view a smaller part of the screen ( a litlle bit less than the right half ) and use the left camera that has more room to view a little bit more that the left half.

This is a model that i created to test ( in theory ) those solutions .

However it can only allow us to estimate how they will work . The only way to know for sure is to test it on the actual table.

Once the exams are over , i will resume working on the table and test the camera setup.

Finally the cameras…

Today we managed to assemble all the necessaries parts to convert the PS3 eye to an infrared camera suitable for our setup. Once again we chose the PS3 eye because of its high frame rate and its low cost.

We are going to describe all the steps that we made in order to convert the camera.

First of all these are the parts that we need:

m12x0.5 Lens mount

IR band pass filter ( 850 nm )

vari-focal m12 lens 2.8-12mm

 

Ok , so lets start with the conversion…

First we remove the black screw covers…

…and after that we have to pry open the case.This can be a difficult task and it requires alot of attention because if the screw driver slides inside the case it can damage the circuit board.

This is the back of the camera with the back cover removed,

and the hole pcb removed.

At that point we have to remove the stock lens and replace it with the m12 lens. The only problem here is that we couldnt find one that fits in the place of the stock one. After some research we made we found that there is a really cheap web cam that has the mount that we need.

So we went out and found that camera and we scavenged the needed part !

Here are the pictures :

and this is the mount.

We have to prepare the m12 mount by cleaning and inserting the IR band pass filter.

So lets go back to our camera …

we remove the stock lens…

…and fit the new m12 mount with the filter a.

We are almost done. We assemble the camera…

…and fit the vari-focal lens…

And we are DONE!!!

 

…and one beautiful photo all the components .

The supporting structure – Box

We have to decide on how to design the supporting structure in a way to be visually pleasant and functional.

We are using SketchUp  to design it and we made a few test structures in order to decide on which one to settle.

Test structure to determine the visual result.

 

And this one trying to select the appropriate measures.

 

and some weird designs …

 

Finally we chose that design and particularly we decided to make it modular meaning that the top can be separated from the bottom in order to move the whole structure easily.As you will see from the next pictures the top part is quite big and because of that it is not possible to fit through doors as is.

These are the actual dimensions of the bottom part of the table…

… and these are the dimensions of the top part…

… and the details of the top part that is used to support the plexiglass.

And a picture we top and bottom together along with the dimensions.

We contacted a local carpenter and luckily in a few days we are going to have the finished table!

Once the table is here we will have to work out on how to support all the components inside it. We have to take special care for the mirror ,the projector ,the IR cameras , and the pc.