The OpenGL Demo
The Flock of Birds is a motion tracking device that allows you
to get position and orientation information for up to 7
You could use this information to run a real-time simulation in
OpenGL, or write the data out to a file to be used as motion capture
data in Maya.
How the Flock
of Birds Works
- Download the sgiflock software to
your home directory. This software was written by Greg Schmidt.
- Install the software following Greg's
instructions (read the README
- You will compile a few drivers with the included Makefiles, and
create a library directory (usually, /u/username/lib) to copy the *.so
- You must set the path to this new library directory. Type:
setenv LD_LIBRARYN32_PATH /u/username/lib
OR add the line
to your .cshrc if you will use the flock a lot.
Using the Flock of Birds
- The flock of birds works by using magnetic fields.
- There is a large black transmitter sitting on a stand that produces
a magnetic field.
- We have an array of seven sensors that can each sense changes in the
magnetic field to report position and orientation information.
- The sensors will not work near metal or magnets (including computer
monitors and speakers). They also don't do well right next to each
- The transmitter is elevated to utilize all of it's three-dimensional
range. It has an effective range of about 10 feet, although you
will notice distortion near the edge.
- You can expect to get roughly 100 samples/second when using one
- To use the flock, you must write C code using the provided drivers.
- First get your setup ready by attaching sensors and orienting the
transmitter in the desired direction.
- We currently have seven sensors available for use. PLEASE keep
the area clean by coiling the wire up when you are done with the
- Check to see that the A/B switch is set to B for the SGI (gurgi).
- Switch on the power source under the A/B Switch.
- Switch on the Flock Hardware by pressing the blue button.
- Run your executable.
- Get used to how the sgiflock class works, and check the documentation
as well. This provides some idea as to the class constructors and
methods. Also see the demos section below.
- When you are ready to turn off the hardware, power down in the
opposite order that you turned the units on. DO NOT LEAVE THE UNIT
ON OVER NIGHT!
- Note: If the flock refuses to take samples, then the system needs to
be reset by powering down and then powering back up. (Hint: make
sure you gracefully shut down the data stream when exiting your
- Compile the demo programs written by Greg Schmidt.
- These demos show the use of the sgiflock object and its constructors
and methods, and show various outputs for various numbers of sensors.
- You can get output as
- position (x, y, z)
- This output can be used for real-time programs, or can be written to
a file for use as motion capture data in Maya. You just have to
- In addition to Greg Schmidt's demos, I have written a simple
demo using OpenGL to translate and rotate an RGB color cube based on
the real world values given by sensor 1.
Now you know how to use the Flock of Birds.
Any questions? Just ask!