This technique projects accurate patterns onto a target and then measures the displacement or distortion in order to calculate the shape, size or position of the object. In the easiest form, a line is projected onto a target and observed under a known angle from a camera. The distortions in the line can then be translated into height variations. This technique is often referred to as laser triangulation. Structured illumination is often used to obtain height information and especially for 3D inspection tasks.