mercoledì 13 maggio 2009

Headtracking using Wiimote and Freetrack

This tutorial will show you how to use your wiimote as an headtracking device.
we'll assume that you already know how to connect the wiimote to your pc via bluetooth.
as you can read from Johnny Chung Lee site, speaking of the wiimote

" It contains a 1024x768 infrared camera with built-in hardware blob tracking of up to 4 points at 100Hz. This significantly out performs any PC "webcam" available today. "

also, the wiimote has in-device preprocessing of image data, this means that the wiimote take
care of all the processing, thus unloading the cpu.
that's why the wiimote is a perfect solution for headtracking and, with a bit of work, the results
are comparable to the (way much more expensive) TrackIR
and of course it is a great weekend project that I'm sure will give you some
other ideas on how to use the wiimote with a pc.

So, to recap, you need the following hardware

- Wiimote
- Led Pen or other IR source
- bluetooth adapter

as for the software, you'll need

- FreeTrack 2.2
- Bluetooth Stack compatible with Wiimote

for the bluetooth hardware and software I suggest you check out
this page on

I assume you already have a working-on-pc wiimote.
Let's build then a really simple IR Led Pen

there's a great IR LED pen schematic from the ubiquitous Johnny Chung Lee
but for this project I've taken another approach.
I had a spare Flashlight that came free with an AA battery pack so I decided
to mod it and I just had to buy some IR leds.

this is the flashlight I'm going to destroy.

now this is what I call luck. the original led was really easy to remove because it was not soldered.
it was just placed between two metallic plates
so this is just too good to be true..

I just need to cut out the pins and
insert the IR Led.

the IR Led in place

to check out that the IR Flashlight is working I used my digital camera,
a Sony DSC-V1. this digital camera has a night mode that cover the sensor with an IR filter

this is the assembled IR Flashlight turned off

the IR Flashlight turned on.
I'm glad it worked on the first try

once you have a working IR Led pen or IR Flashlight or whatever your IR source is
(just don't put a candle on your head!) you just have to download and setup Freetrack

Note: connect the wiimote before launching FreeTrack, otherwise it won't be recognized.

Select Camera from the Cam panel, then choose
Wii Remote #1 and click the Start button below

if everything went fine, you should see that the first and last blue led
on the wiimote are lit, now you should see a skull on the left panel

point the IR source to the wiimote and voila
you should see a red dot floating around and also you'll see the skull look around accordingly to the
red dot. If you see more than a red dot or if you don't see it at all, move the threshold bar until you see it. for this project I assume that you're using a IR source with only one led, check out the FreeTrack site for info on how to build a IR device with more than one. note that with more IR Led you can achieve more degree of freedom (DOF) but for a basic headtracking device you just need
one led.

Also note the incredibly fps of the wiimote, it easily goes up to 100 fps!
by the way you don't need a wiimote to use FreeTrack, you just need a webcam.
for more info check out FreeTrack.
basically FreeTrack is compatible with games that support TrackIR so check out TrackIR site
for compatible games.
don't forget to check out the other panels of FreeTrack to setup the sensitivity of the device,
and other settings. also check out for some option to turn on TrackIR support into the specific
game. usually inside compatible games there's an option to bind a key to center TrackIR view.

Find a suitable place for the wiimote, for this project we found out that the best place was above the LCD. check it out

also you have to place the IR Source above your head.

this is a serious project. don't laugh.
by the way I would like to thank Snow for his support, for letting me take this picture and for being a great friend. thank you Snow!

now for some in-game tests!
we had some fun trying out this device with GTR2 and a Force Feedback wheel, the Saitek R440

check out the following videos to see this device in action

Part One

Part Two

Part Three

stay tuned for a better device with more DOF!

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