Commonly used three-dimensional scanner according to the different sensing methods, divided into contact and non-contact two kinds. Contact with the probe head directly in contact with the surface of the object, through the probe head back to the photoelectric signal converted to digital surface information, so as to realize the object surface scanning and measurement, mainly to the three coordinate measuring machine as a representative.
Contact measurement has a high degree of accuracy and reliability; with the measurement software, it can quickly and accurately measure the basic geometric shapes of objects, such as faces, circles, cylinders, cones, spheres, and so on. The disadvantages are: high cost of measurement; the probe is easy to wear. Measurement speed is slow; detection of some internal components have inherent limitations, so to seek the true shape of the object will need to compensate for the probe radius, which may lead to the problem of correction error; contact probe in the measurement, the force of the contact probe will make the probe tip part of the probe and the measured part of the local deformation between the measured value of the actual readings; due to the inertia of the trigger mechanism of the probe and the time delay to make the probe to produce the beyond phenomenon, convergence speed will produce dynamic error.
With the emergence and development of computerized machine vision as an emerging discipline, the use of non-contact photoelectric methods for rapid measurement of the three-dimensional shape of surfaces has become a major trend. This non-contact measurement not only avoids the need to compensate for the probe radius in the contact measurement of the trouble brought about by the probe radius, but also can realize the various types of surfaces for high-speed three-dimensional scanning.
At present, there are many non-contact three-dimensional scanners, according to the different sensing methods, commonly used based on laser scanning measurement, structured light scanning measurement and industrial CT, etc., respectively, on behalf of the market mainstream three-dimensional laser scanner, photographic three-dimensional scanner, and CT tomography scanner.
The use of non-contact three-dimensional scanner because of its non-contact, the surface of the object will not be damaged, at the same time compared to contact with fast speed, easy to operate and other characteristics of the three-dimensional laser scanner can reach 5,000-10,000 points / second speed, while the photographic three-dimensional scanner is the use of surface light, the speed is to reach a few million measurement points in a few seconds, the application and real-time scanning, industrial inspection has the characteristics of the three-dimensional laser scanner. Application and real-time scanning, industrial inspection has a good advantage.
Two, the principle of three-dimensional scanner
Photographic three-dimensional scanner is a high-speed, high-precision three-dimensional scanning and measuring equipment, the application of the most advanced international structured light non-contact photographic measurement principle. Using a combination of structured light technology, phase measurement technology, computer vision technology, composite three-dimensional non-contact measurement technology. It adopts white light raster scanning, works in non-contact 3D scanning mode, fully automatic splicing, has the advantages of high efficiency, high accuracy, high life span, high resolution, etc. It is especially suitable for reverse modeling of complex free-form surfaces, and is mainly applied to product R&D and design (RD, e.g., rapid prototyping, 3D digitizing, 3D design, 3D stereo scanning, etc.), reverse engineering (RE, e.g., reverse scanning, reverse design) and 3D inspection CAV), is a necessary tool for product development and quality inspection. The 3D scanner is also known as laser transcription machine or 3D transcription machine in some areas.
Photo optical 3D scanner, its structure is mainly composed of grating projection equipment and two industrial-grade CCDCamera, by the grating projection on the object to be measured, and to be coarse and fine changes and displacements, with the CCDCamera will be captured by the digital image through the computer algorithms processing, you can know to be measured object of the actual 3D appearance.
The photo 3D scanner adopts non-contact white light technology to avoid contacting the surface of the object, and can measure the model of various materials. During the measurement process, the object to be measured can be arbitrarily flipped and moved, and the object can be measured from multiple viewpoints, and the system can be fully automated for splicing to easily realize the object's 360 high-precision measurement. And can be in the acquisition of surface three-dimensional data at the same time, rapid access to texture information, to get a realistic object shape, can be quickly applied to the manufacturing industry scanning.