Gaze Angle is Absolute. How can I calculate it with respect to Camera ?

[Prashant-Kesharwani]

Hello Tadas,

Thank you so much for sourcing this useful repository, I have some questions, kindly look into this:

I ran OpenFace for gaze estimation with another face detection model on Columbia Gaze Dataset, Image : 0033_2m_30P_0V_0H

and the results are: Gaze Angle (Degrees): (-18.870744753694947, 7.512340676394768)

These angles are w.r.t. eyeball, how can I calculate w.r.t. camera ?

We tried your approach but could not get correct results : https://github.com/TadasBaltrusaitis/OpenFace/issues/865#issuecomment-619188237

def calculate_angle_between_vectors(vector1, vector2):
    dot_product = sum(a * b for a, b in zip(vector1, vector2))
    magnitude1 = math.sqrt(sum(a**2 for a in vector1))
    magnitude2 = math.sqrt(sum(b**2 for b in vector2))
    cos_theta = dot_product / (magnitude1 * magnitude2)

    # Handle edge cases to avoid math domain error
    cos_theta = max(min(cos_theta, 1), -1)

    # Calculate angles in x and y directions
    x_angle_in_radians = math.atan2(vector2[1], vector2[0])
    x_angle_in_degrees = math.degrees(x_angle_in_radians)

    y_angle_in_radians = math.atan2(vector2[2], vector2[0])
    y_angle_in_degrees = math.degrees(y_angle_in_radians)

    return  x_angle_in_degrees, y_angle_in_degrees

# here eyeball centre is 3d location of eyeball centre and eyeballCentreNormalised is ray from (0,0,0) to eyeballcentre.
eyeballCentreNormalised = eyeballCentre / norm(eyeballCentre);
gaze_absolute = gazeVecAxis / norm(gazeVecAxis);

#Here we calculate the angle between gaze_absolute and the ray from eyeballcentre
x_angle_degrees, y_angle_degrees = calculate_angle_between_vectors(eyeballCentreNormalised, gazeAbsolute)

The Output of this method was: X-angle: 157.61 degrees Y-angle: -111.96 degrees

I suppose, these are not correct angles. Kindly guide me how to proceed further on this issue.

Regards, Prashant

[kendrew06]

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