======FaceIdent======

See also [[FaceIdent dev log]]

A simple approach to face identification, built on top of OpenCV and given a 
YARP network interface.

The program has two modes of operation. The first is calibration, where each user
must show their face to the camera separately - press the number keys to assign 
each user with a different ID. You can see which face is mapped to which ID at 
the bottom of the window. 

The second mode of operation is face detection, where each visible detected face
is given an ID based on it's closest match (within a given error threshold) with 
the faces recorded during calibration. The boxes drawn around the faces display 
the id and the confidence value of the match. When in this mode the program sends 
the following YARP messages:

^ Port ^ Bottle contents ^ Meaning ^
| /faceident | "user appeared" ID confidence | A user has entered the view of the camera |
| /faceident | "user disappeared" ID | The user has left the camera view |

You can also drive the program via yarp with the following input messages:

^ Input port ^ Bottle contents ^ Meaning ^
| /faceident-ctrl | "train" ID | Train for this user |
| /faceident-ctrl | "detect" | Switch to detection mode |
| /faceident-ctrl | "save" sessionname | Save the detected faces  |
| /faceident-ctrl | "load" sessionname | Load previously detected faces  |
| /faceident-ctrl | "clear" | Clears all faces |
| /faceident-ctrl | "idle" | Switch to idle mode, mostly frees up cpu |

Faces are saved in png format along with a text file to map them to id numbers. The sessionname 
will be prepended onto the filenames for the text file and the image files, so you can save 
multiple sessions.

Keys:

^ Key ^ Meaning ^
| 0-9 number keys | Calibrate a given id against a face in the scene |
| d | Start detect mode, which will send YARP messages |
| c | Clear all faces in the database |

Requires: OpenCV, YARP

Written and tested on Linux, but it should work in Windows too.
At the moment you'll probably have to run it with:

simple-faceident --cascade=/path/to/haarcascade_frontalface_alt.xml

In order to find OpenCV's data, on my machine it's in:
/usr/local/share/opencv/haarcascades/haarcascade_frontalface_alt.xml

Todo:
  * Try normalised cross correlation instead of image differencing
  * Expose image size and error threshold via yarp
  * Use tinyxml or something better for the serialisation

Source code: [[http://svn.lirec.eu/foam/trunk/simple-faceident/]]