pol = concat( machine_rear_profile,
[ below_point ],
machine_front_profile);
skew_angle = atan2( first_front[1] - first_rear[1],
first_front[0] - first_rear[0] );
echo(below_point, pol, skew_angle);
pol = concat( machine_rear_profile,
[ below_point ],
machine_front_profile);
skew_angle = atan2( first_front[1] - first_rear[1],
first_front[0] - first_rear[0] );
echo(below_point, pol, skew_angle);