The most evident limitation of a two-dimensional vision system is its ability to move and rotate only in the X-Y plane. This has led to a demand for high quality, three-dimensional (3D) processing technology, the use of which is increasing. For engineers exploring the use of 3D inspectionCONTROL ENGINEERING China版权所有, there are now many different technologies available for creating 3D images.
        The most important task for engineers to successfully create such an application for industrial use is to achieve a high measurement resolution in all (x, y, z) directions. Depending on the shape and size of the object and the distance between the object and the vision sensorCONTROL ENGINEERING China版权所有, different methods of three-dimensional measurement控制工程网版权所有, and different types of active vision systems, can be used.

        A 3D object model

        3D image acquisition

        The vision system consists of a set of deviceswww.cechina.cn, which convert light and measurement data into information, with spatial and material attributes of the scene. These devices have photosensitive sensors (a camera with a lens which focuses images on a photosensitive element or the eye) and computational mechanisms (a computer) allowing information to be collected from the sensors.
        Humans can easily distinguish objects they see and are also able to recognize them in various light conditions and from different frames of reference. However控制工程网版权所有, in the case of vision systems, the proper interpretation of a pixel value is a very difficult task. Additionally, the brightness of pixels (and thus of the image received) depends on several factors:
        •Scene geometry - the shape and position of the object in the field of vision (when the shape or the position is cha