Triangulation

Triangulation, or three-point measurement, is a measurement where one uses the characteristics of a triangle. It is based on the mathematical characteristic of a triangle, that the form can be determined without all characteristics being known (Goniometric). A triangle has three sides and three corners, so 6 characteristics in total. With three of the six characteristics alone, the triangle can be determined. This principle applies to five combinations as well as one exception: with the combination of three corners, the scale cannot be determined.

When one wants to apply triangulation in a 3D vision system, the triangle is formed by the following three components – a camera, a laser and an object on which the light falls. Because the camera angle, the laser angle and the distance between the camera and the laser are known, the distance in relation to the object can be determined. Additional 3D information can be gathered by moving along the object. This way, x and y positions of the object can be determined as well as forms, based on the place the reflected light falls on the CCD sensor of the camera.

A great advantage of triangulation is the simplicity and reliability of the system. A disadvantage is that only one single distance measurement can be done with one single shot. When one needs more information about the object, one will have to move the object along the arrangement or to move the arrangement along the object. Only with multiple images and the comparison between these, a more complete 3D visualization of the object can be generated.