'**SUMMARY**
Returns the mean of the distance between corner points in the chessboard
Given that the chessboard is of a known size, this can be used as a
proxy for distance from the camera
**RETURNS**
Returns the mean distance between the corners.
**EXAMPLE**
>>> img = Image("corners.jpg")
>>> feats = img.findChessboardCorners()
>>> print feats[-1].area()'

def area(self):

    sqform = spsd.squareform(spsd.pdist(self.points, 'euclidean'))
    a = sqform[0][1]
    b = sqform[1][2]
    c = sqform[2][3]
    d = sqform[3][0]
    p = sqform[0][2]
    q = sqform[1][3]
    s = ((((a + b) + c) + d) / 2.0)
    return (2 * sqrt((((((s - a) * (s - b)) * (s - c)) * (s - d)) - (((((a * c) + (b * d)) + (p * q)) * (((a * c) + (b * d)) - (p * q))) / 4))))
