Laser measurement.
Enables the measurement without contact and high accuracy of long distances (up to 150 m). A head situated in the 0 point emits a laser beam that bounces off the surface of the object whose position we need to know. The same head receives the reflection of mentioned beam and calculates the distance from the time it took to make the travel back and forth.
This system allows high accuracy and speed of reading.
Occasionally it is affected by light pollution but we have suitable versions for each application.
Ultrasounds
The ultrasound devices measure the position of a surface thanks to the calculation of the bounce time of the beam. While the system is totally immune to the environmental lighting, the precision obtained is lower than the laser system and requires a larger area because the emission angle is much longer.
It is used in short distances (up to 10m).