Scanning the World: How to Digitize Art
The age of digital technology has posed the challenge of transferring the world around us into an electronic format. This is accomplished by scanning ancestral texts and images, by digitizing terrain for navigation, by transferring layouts for design, and even by scanning distant objects in our universe. Technologies designed to achieve this goal exist both in the form of expensive industrial solutions, and quite accessible, which can be made by your own hands. In this article we will talk about the different options.
History has left us many cultural values, a significant part of which are pictures of the peoples of the world. The 21st century allows anyone to look at them using digital technology.
To transfer a work of art into digital format without losing the quality of the original is not an easy task. Let’s understand how to do it.
Scanners are used to obtain high quality digital copies of images. Their principle of operation is quite simple: light emitted by a lamp is reflected from the image surface through a series of mirrors onto a CCD. Scanning ordinary paper is a simple matter for these devices.
However, when it comes to digitizing oil paintings, the task becomes more difficult. This is where a whole range of circumstances come into play that impede the normal scanning process. For example, original paintings can be easily damaged by scanning, they have non-standard sizes (take for example Alexander Ivanov’s Appearance of Christ to the People), and besides the oil paint is in relief, which can also make the result much worse.
The first thing that comes to mind in such a case is the use of conventional photography, especially given the advances in high-resolution matrix technology. But it’s not all smooth sailing either. Photo matrices rarely have a resolution of more than 30 megapixels, which would give a picture with an area of one meter a sharpness of 140 dpi – this is too little.
It is also worth taking into account that unlike a linear CCD scanner, the camera shoots from a single point, so distortions are bound to occur. There is a way out of this situation: the image is scanned in parts instead of the whole picture.
Volumetric scanning methods
Devices that scan two-dimensional images became part of our lives long ago. But what if you need to digitize a three-dimensional figure? With today’s technology, that’s not a problem either. You can find devices on the market that allow you to scan a wide variety of objects – from costume jewelry to entire buildings.
The question of the possibility of creating digital images of three-dimensional objects appeared quite a long time ago, but the need that existed at the time did not justify the mass production of such devices. 3D scanners were produced in single copies and were extremely expensive.
A major impetus for their development was the transition of the largest companies to fully three-dimensional design of their products. It simply became impossible to assess the quality of parts in mass production on fully automated numerically controlled machines the old-fashioned way, checking dimensions against blueprints. Volumetric scanning technology came to the rescue.
How does it work?
The first 3D scanners were contact ones, which meant that a “stylus” moved along the surface of a model mounted on a special rotating stand, the information from which was recorded and processed by a computer. Such installations for digitizing a complex part could take up to a month of work.
That all changed with the development of semiconductor lasers and digital matrices. Today, there are three basic methods of volumetric scanning.
Laser-distance (lidar) scanning is based on determining the distance to a point on an object by calculating the time the laser beam travels to and from that point. Modern electronics makes it possible to calculate this time with the highest accuracy. However, there is the other side of the coin: scanning takes place in one point, so it takes quite a long time to build a model this way.
A modern laser-distance scanner is capable of reading up to 100,000 points per second. The resulting array of points is approximated by numerical methods in the surface. And software algorithms can then recreate the theoretical surface of the object, eliminating all unnecessary roughness and inaccuracies.
In the triangulation laser scanner, the deflection of the reflected beam from the optical axis of the detector lens is measured (see diagram below). A significant advantage of this method is the possibility to make the beam flat and use a two-dimensional matrix to scan the entire beam projection on the object at once, rather than points separately. This greatly speeds up the digitization process and simplifies subsequent data processing.
At the same time, the method has its disadvantages: for example, holes located away from the optical axis of the laser may be obscured, which requires a refined scanning and special algorithms for converting the scanned areas.
Optical scanners consist of a projector (a laser can be used) that transmits a grid to the object surface and a camera that is placed at some angle to the projector and registers distortions of the grid lines. The scanner software analyzes the curvature of the grid and produces a depth map based on it. This method is inferior to laser scanners in accuracy, but far superior in scanning speed and cheapness of manufacturing.
Such a scanner can be easily created practically at home: all components can be found on sale and software has been available on the Internet for a long time. An additional feature of such scanners is the perception of an object’s color.
In areas where accuracy is not so important and it is necessary to scan large objects, ultrasonic and radar scanners are also used.
Why do they do that?
Quality control is the most obvious, but by no means the only way to apply 3D scanning technology. 3D scans are now used in many fields, from medicine to astronomy (for example, space objects are scanned using radio waves to make detailed three-dimensional portraits of them). 3D scanners are also being used in fields such as design and creativity.
Scanning in Modeling
Designing household items, controls and generally everything a person touches with his hands in a virtual environment is quite difficult to achieve proper ergonomics. This leads to a wide range of devices and appliances on the market that are beautiful to look at, but not very comfortable to use. For example, there are thousands of computer mice, but only a few are really comfortable.
In such a situation, a 3D scanner is simply irreplaceable. Having digitized manually molded model, it is easy to transfer it to a suitable format and, having smoothed the inaccuracies unavoidable in manual production, obtain a ready-made model, luckily all the necessary software is already on the market. For example, the RapidWorks software package from NextEngine allows the entire process to be carried out in semi-automatic mode.
3D scanners and creativity
The area in which 3D scanners have revolutionized is computer graphics. Before, artists had to spend hundreds of hours modeling realistic people for movies and computer games. Now it is possible to simply find the right person and digitize them with a 3D scanner.
These devices have also greatly simplified the mass production of various figurines. Now it is enough to mold one figure, scan it, and thousands of them can be made on CNC machines.