The Matlab interface to the vision server consists of a single routine to
interact with the vision server: mVision. Connection to and interaction
with the vision server are achieved by using different arguments to the
mVision function.

The mVision function performs three different functions: opening
communication with the vision server, requesting data for a particular
object from the vision server, and closing communication with the
vision server.

The vision routines use port identifiers to maintain connections to the
vision server. By using this system a single Matlab session would be
able to make connections to multiple vision servers or to make multiple
connections to a single vision server. Each time a connection to a vision
server is opened with the 'open' command it should later be closed with
the 'close' command.

Typically the usage is of the form:
    result=mVision(command [, options])

The available commands are:
   'open' - Open a connection to the vision server
    Arguments: The character representation of the TCP/IP address of the 
               machine running the vision server 
    Returns: A port identifier used for future communication with the vision
             server.
    Example:    
        vis_port=mVision('open','127.0.0.1');
        % Open a connection to the server on the machine with address
        % 127.0.0.1 (This is a loop back address - it will always connect 
        % to the machine on which the Matlab session is running)
        % And save the port identifier in the vis_port variable

    'close' - Close the connection to the vision server
    Arguments: A port identifier created by the 'open' command
    Returns: Nothing
    Example:
        mVision('close',vis_port);
        % Close a connection to the vision server that was created earlier
        % and who's port identifier was stored in the vis_port variable.

    'get' - Get information about an object
    Arguments:
        A port identifier created by the 'open' command
        A character representation of the name of and object on the current
        vision server. The object should be either a Rectangle, a Circle, or
        a Line type object.
    Returns: 
        An array of four elements. The meaning of each element different
        depending on the type of object for which information was requested.
                 ret(1)             ret(2)        ret(3)           ret(4)
Rectangle x coord of corner   y coord of corner   width            height
Circle    x coord of center   y coord of center   radius           radius
Line      x coord of start    y coord of start  x coord of end  y coord of end

    Example:
        loc=mVision('get',vis_port,'Ball');
        % Request information about an object called "Ball" from the 
        % vision server who's port identifier was stored in the vis_port
        % variable.  
        % If the "Ball" object is a circle that is being tracked, 
        %    loc(1) = X coordinate of the center
        %    loc(2) = Y coordinate of the center
        %    loc(3) = radius
        %    loc(4) = radius