Howto: Compile Touchlib in Windows
Howto: Compile Touchlib in Linux

Both compile instructions apply to subversion rev.73 of touchlib. If you followed the Howto’s and still have some trouble please post the problem in the comment section.

After the last blog not much had to be done about the FTIR screen. Actually I only used some tape to hide the wires on the sides.
With all LED’s in place and the frame being placed on two chairs it was time to finally test the FTIR screen.

All LED’s are fully functioning !

Testing with 5 and 2 fingers…

10 finger test:

Video containing a summary of the project and some demo applications

To get the Touch Tracer tool (from the demo video) please click on read more.

Project description:
Name: Touch Tracer
Purpose: To display recognized blob’s and for debugging purpose

Install instructions:
1. Put all files (touch_tracer.exe and *.bat files) in the same dir as touchlib.dll
2. Either run the bat files or edit them.
touch_tracer.exe requires 4 arguments: width height bitdepth refreshrate
example: touch_tracer.exe 1024 768 32 60

General note, as the readme.txt states, this application needs libraries of visual studio 2005. If you don’t have those, you will be prompt with an error message.

Todo:
1. Show the path of a tracked blob and let it fade away over time.

Download:
Touch Tracer v0.1 Binary

Optional downloads
Visual Studio 2005 SP1 Redist. Package (URL Offline)
Entire package if the one above fails -> Get it from microsoft

As power source for my LED’s I will be using a 12V DC Adapter (1000 mA).
To calculate the LED array and the amount of needed resistors I used an internet tool the LED Wizard.

According to the wizard I should create 5 array’s of LED’s. Each array should contain 6 LED’s and one resistor of 68 ohms.

Click the link below to continue reading.

Needed equipment:
- Workbench
- Soldering iron
- Solder
- Wires and resistors
- Needle-nose pliers
- A steady hand
- Toilet paper!

Bending!
First you should bend the legs of the IR LED’s. I would recommend using Needle-nose pliers to prevent breaking a leg. Also don’t bend it more than once.

Be sure to check the holes you drilled, you really don’t want to get them stuck in there. To prevent the LED’s from being damaged, you should make them a bit larger than the diameter of your LED.

Soldering
Well I didn’t made much photo’s during soldering. But some general hints, don’t heat the legs of the IR LED’s too long because you probably end up melting the LED. Also whenever possible you should try soldering on some plate instead of what I did… soldering inside the small frame. However it makes it twice as challenging though .
After soldering 3 sides, it’s time to put in the acrylic plate. You might want to use some toilet paper to keep the acrylic plate centered (The acrylic plate should not be touching the LED’s). Now closed the frame and continue soldering!

Almost done, just need to attach the power plug…

A new FTIR screen born…

Coming up: First tests on the FTIR screen…

Before actually working on the frame, I made a drawing in AutoCAD. Within this drawing I could easily calculate the amount of IR LED’s I would need and at the same time see how the IR light beams would spread.

FTIR Prototype Drawing

The local tool shop was friendly enough to cut the aluminum frame (H shaped) into the sizes of my drawing.
So at home I just needed to remove the edges in 45 degrees.

Click the link below to continue reading.

Needed equipment:
- Saw (for aluminum/iron)
- Mitre Block
- Clamp
- Workbench
- Drill
- Drill bits (multiple sizes)
- Punch
- Hand-file

First I mounted the aluminum frame in a Mitre Block. To prevent it from moving during sawing, I used a clamp.

After sawing, I used a Hand-file to smoothen the edges. It fits nice:

Next step is drilling holes for the LED’s. Before drilling I used a Punch to make sure the Drill won’t shift during drilling.You could start with a small Drill bit but I just started with 3.5 mm and after that I used 5 mm (which is the size of my LED’s).

Almost done…

To keep the parts into place I used a construction like this:

Next time I’ll cover soldering the LED’s…

I tried to maintain the aspect ratio of a regular screen (4:3). The size of the plate is 41 x 31 cm and about 8 mm thick. The actual area which will be captured is 40 x 30 cm.

Two days after ordering the acrylic plate I received it in a nice package:

In the image below we can see the plate has been cut roughly.

(The plate looks a bit blue but thats due the colour of the protective layer)

Because we want to beam IR light into the sides of the acrylic plate, it is necersaily to polish the sides.

Click the link below to continue reading about how to treat the acrylic plate.

Needed equipment:
- (Wet) sandpaper of the following grit sizes:
P320 (I used Norton T223 / P320 / Very Fine)
P800A (I used Auto-paper P800A / Super fine)
P1200A (I used Auto-paper P1200A / Super fine)
- Brasso
- Old cloth
- Some old newspapers
- A bucket of water
- A lot of Patience! (Really!)

General hint: If you order an acrylic plate, ask your supplier to finish off the edges as smooth as possible.

Polishing step by step
Depending on the state of the edges you should decide how many different types of sandpaper you want to use.

In my case I started with the P320. Since this is “wet” sandpaper you need to soak it in a bucket of water before you can use it! Continue polishing the edges until no scratches of the cutting machines are visible anymore.

After a quick first polish with P320 it should look a bit like this:

If (almost) no scratches are visible, continue using P800A

Just do the edges several times, after this continue with P1200A for a while

To make it all nice and shiny we use the good old Brasso:

Pour some Brasso on a cloth and start wiping the edges.

After doing the sides multiple times, it is time to view the result:

As an example object I took an old guitar string package. You should be able to see “Electric Guitar Strings” in it (a bit mirrored though).

Shipping + Lazyness = … !
In my case the local tool shop did not had acrylic plates which where thick enough (at max 4 mm, and I needed at least 8 mm), so I had to order it online. No big deal though. At the time of delivery no body was home, however it seems that the postman did not felt like returning for the second time, so he left the following note:

Translation: NOTE!: Behind green garbage bin

>_< Like wtf? He left it outside! Thank god my neighborhood is a safe place, it could easily have been stolen …

To be continued
If you made it to this state, your arm is probably hurting from polishing …
take a break and see you next time!

12►

Today I will cover how the lens of the Philips webcam can be dismounted and replaced by one without an infrared (IR) blocking filter.

Most consumer webcams contain an IR filter which will prevent IR light coming through. This is done to prevent image distortion. However in our case we want to capture the IR light. On some webcams it’s possible to remove the IR filter (which is behind the lens and often has a red colour). With our current webcam from Philips this isn’t possible. Therefor a new camera lens has been ordered on eBay.

It was called “4.3MM 4.3 MM CCTV Camera board Lens IR DVR NEW”

Some specifications of the new camera lens:
* Glass Lens
* Focal length: 4.3 mm
* Aperture F/1.8
* Image format 1/3 inch
* Angel of view 68°
* Mount M12 x P0.5
* Size ?14×14.75

Click the link below to continue reading about how to replace the camera lens.

Needed equipment:
- A screwdriver or a swiss knife
- A steady hand
- Some patience

Obviously by following the next steps your product warranty will be over… don’t say I didn’t warned you… but who cares

Step 1: Turn it
Because we don’t want to take the whole camera apart, we will start by removing the lens adjuster (normally used to focus manually).

First turn the lens adjuster counter clockwise untill it won’t go any further. If you feel like it’s being stuck, try a bit harder untill you have something similar as the image below:

Step 2: Removing the lens adjuster.
Now there should be enough space to put a screwdriver in the gap.

You should now be able to take the lens adjuster off. You could do it nice and gently, but in my case I broke a few parts of it . Not something to worry about though.

You can cleary see the CCD sensor:

Step 3: Mount the new lens.
Finally you should be able to mount the new lens. This might be tricky if you got large fingers. You might want to use the lens adjuster as a tool to mount it.

Some extra images
The old (left) and the new (right) lens:

The IR filter on the old lens:

The next blog entry will be about how to polish the acrylic plate.