Contact data acquisition method mainly uses the optical principle of data acquisition, including: laser triangle method, laser ranging method, structural light method and image analysis method, etc..
Contactless data acquisition with high speed and high precision, eliminates the measurement error caused by measurement of friction and contact pressure, avoid contact probe and the measured surface curvature due to shoddy interference problems, the amount of dense point cloud information acquisition, high precision, measuring head production spot can do very small, can be detected by general mechanical probe to measure the position, maximum reflection of real shape of the surface to be measured. The data acquisition method by non-contact non-contact probe, because there is no force, suitable for measuring soft objects; non-contact probe sampling rate was higher in the 50 to 23000 times / second, suitable for complicated surface shape measurement, unknown surface accuracy is not particularly high for automobile the wood, mud, household appliances etc.. But the non-contact probe influenced by the object's surface characteristics (color, brightness, roughness, shape) is greatly influenced by the current, in most cases the error ratio of contact probe to maintain more than 10 micron. The method is mainly used for the measurement of the parts that are easy to deform, the precision demand is not high, the parts that require massive data, the measurement cost and the related software and hardware are not considered.