Predicting height of a person using one image

Question

I am trying to predict the height of a person from a single picture. I discovered that the length between the knuckles of a person and the ground is between 60-65 cm and this can be used as the constant. As we know the measurement of one distance between two points of a picture hence we should be able to predict the distance between other points.

But it doesn't seem to work:

# I am using Media-Pipe Module: please advise if there is any other better module which I can use
# Media Pipe module is to predict the pose of the person

elbow_to_shoulder = (calculate_distance(l_elbow,l_shoulder) + calculate_distance(r_elbow,r_shoulder))/2
print(elbow_to_shoulder)

mean_of_legs = ((calculate_distance(l_hip,l_knee) + calculate_distance(l_knee,l_ankle) + calculate_distance(l_ankle,l_heel)) + (calculate_distance(r_hip,r_knee) + calculate_distance(r_knee,r_ankle) + calculate_distance(r_ankle,r_heel)))/2
print(mean_of_legs)

This is where the measured height is actually 168 cm but according to this prediction it is 119cm [