Read Part 1 of Inspired 3D: Modeling Resources.

All images from Inspired 3D Modeling and Texture Mapping by Tom Capizzi, series edited by Kyle Clark and Michael Ford. Reprinted with permission.

3D Scan Data
The main difference between digitizing a model and using 3D scan data is that the modeler is usually the one operating the digitizing stylus. But most 3D scanning devices and software are too specialized and complex for the modelers to operate themselves. This is not to say that modelers cannot learn to operate this equipment if they wanted to; it is only that this equipment is not as automatic as the equipment manufacturer would like the customers to believe. People who have been using the equipment for many years do the best scans. When it comes to 3D scan data, the modeler must understand what it is used for and how it is obtained. It is not important, however, that the modeler uses the 3D scan system to get the data.

A 3D scanner samples points from the surface of the 3D object. The output that can be expected from a 3D scanner normally consists of a polygonal mesh that is the actual size and shape of the object being scanned (Figure 12). In recent years, scanners have become more sophisticated. Scanners have expanded their capability to include the acquisition of color and texture data as well as 3D geometry data. The properties of an object that can be captured during scanning include shape, size, color and texture.

[Figure 12] A 3D scanner provides excellent 3D reference material for modeling, but the data is too dense to be used in production.

3D scanning is the term that describes several different technologies. Recent developments in 3D data acquisition from physical objects are more like photography than actual scanning. However, because the data that is rendered from the processes is similar to the data that is gathered from traditional 3D scanners, these processes will be included in this section as well. The two primary ways that 3D scanners are used for computer modeling are laser scanning and structured light scanning. Other methods of acquiring 3D data are out there, but if the modeler understands the basics involved with these two main types, the other techniques will be easier to grasp if they are needed for a project.

Laser Scanners
Laser scanners use a laser. The laser is a device that emits a single beam of intensely directed light. The laser is mounted in a moving device and gathers 3D information by bouncing the laser light back into one or more cameras mounted in the moving device. A laser diode and stripe generator can be used to project a laser line onto the object (single point, line or multiple lines). The line is viewed at an angle by cameras so that height variations in the object can be seen as changes in the shape of the line. The resulting captured image of the stripe is a profile that contains the shape of the object.

Laser scanners use the principle of triangulation to gather 3D data. A laser line or pattern is projected onto a part. An optical camera offset from the laser source views the laser light on the object being scanned. The 3D data is obtained by calculating the differences between the points measured closer to the laser and the points farther away from the laser.