3D printing and spatial printers specially used for it are now a very popular and very emotional topic that practically everyone has heard about. However, the world of 3D printing is not just printers. In addition to them, there are also 3D scanners. What are they and how do they work?
While classic scanners transfer a flat image to digital form, 3D scanners are designed to transfer real three-dimensional objects to image files. Only these devices will allow us to see a specific object on the computer screen in the form of a three-dimensional model, and not an ordinary photo. The 3D scanner collects geometrical data from the surface of the object and on its basis its digital form is created
1. 3D scanners – touch and non-contact.
Due to the way we operate, we distinguish two groups of 3D scanners – operating in a touch and non-contact way.
For contactless scanners, the measuring head must contact the scanned object. This method is therefore invasive, which means that during scanning, the surface of the scanned object may be damaged. The scanner thoroughly analyzes the shape of the object using a special probe located on the CMM or measuring arm. This method is time consuming but very accurate. It is mainly used in the case of projects requiring special precision of measurements, such as engineering projects and the first checks of finished products.
Non-contact scanning is a non-invasive method that does not require contact with the surface of scanned objects. Objects are scanned remotely, so there is no risk of damage to or damage to their structure. It is irreplaceable for objects with large and inaccessible surfaces as well as very delicate ones.
2. Non-contact scanning – two methods
In touchless scanning alone we distinguish two methods: using laser rangefinders and based on structured or laser light.
Non-contact scanning method using laser rangefinders
Our accurate knowledge of the speed of light allows us to easily and quickly calculate the time of reflection of the laser light from the object. Thanks to this, we can determine the distances of all points of the model, and the scanner calculates their location in space. This technology is based on very accurate sensors.
Non-contact scanning based on structured or laser light
3D scanners using this method have a built-in matrix that records the coordinates of the scanned item without disturbing its surface. Complete information about the appearance and geometry of the object is collected very accurately here.
Among the scanners using this method we will find, among others, a scanner consisting of many DSLR cameras (i.e. SLRs). In this case, scanning is based on the principle of photography and reproduction of shapes, size and relative position of points on the basis of the resulting photos. The advantage of such a scanner is the speed and the ability to freeze motion.
3.Import of scanned points to CAD programs.
The 3D scanner after collecting all the necessary information from the surface of the object creates a file containing a cloud of points. It contains information about placing these points in three-dimensional space, saved in the form of the X, Y and Z coordinate system. After reading and processing the data saved by the scanner, special CAD systems create a ready spatial model that can be saved in a file such as STL or IGES.
4.Application of 3D scanners.
Models obtained with 3D scanners can be used in various fields. They can be edited using appropriate graphic programs. After proper processing, the models can be helpful in engineering and construction works, they are useful during computer analyzes, where accurate reproduction of every detail is crucial. The possibilities offered by 3D scanning are also very helpful in architectural work related to the inventory of monuments, accurate reproduction of both the solids of entire buildings, as well as their individual details and interiors.
3D scanners are also used in reverse engineering, dealing with the reconstruction of existing objects, as well as the implementation of new ones. In this area, thanks to 3D scanning, you can both restore the missing design documentation and update the as-built documentation. In addition, computer models created on the basis of scanning also allow you to create virtual simulations, useful, inter alia, in geodesy.
3D scanning technology is also used in the film industry, where it helps to transfer live characters to the fairy-tale world. It may also be surprising that individual customers who want to have miniature figurines of their loved ones, home pets and themselves are also interested in this technique.