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3D scanning is used for capturing the surface characteristics of a physical object using a 3D scanner. The output of scanning is the generation of a 3D model file that can be edited using designing software or can be taken for 3D printing directly. The objects to be scanned can be a real‐time object, natural scenarios (place/surroundings), or a person. The information obtained during scanning can be extracted and reproduced using a process called reverse engineering (Guo et al. 2019). Considering the affordability, portability, and versatility, reverse engineering employs two types of 3D scanning equipment namely contact and non‐contact scanners (Table 1.3). Contact scanners are point‐based systems that employ a probe to touch the object to be scanned. Both data collection and designing can be done simultaneously using a portable coordinate measuring machine (CMM) (Martinez‐Pellitero et al. 2018). On the other hand, non‐contact 3D scanners use an array of laser/ light beams to extract the surface information of the object. These types of scanners project either a laser beam or structured light on the object that aids in capturing the surface data. A web camera which on integration with software aids in transferring the reflected beam into the 3D model data for printing (Wei et al. 2019). Based on the mode of applications, 3D scanners are categorized as desktop scanners (EinScan, Solutionix 500) and handheld scanners (Sense, EinScan Pro 2X, Structure sensor). Most of the scanners are adaptable with computers while some other advanced versions employ the iPad to transfer the 3D model.

Another type of scanning technique is photogrammetry in which 3D models are obtained from 2D photographs by integrating computer vision and computational algorithms. Photogrammetry is based on analyzing several static points in the 2D photographs taken from different views so that it would detect the pixel corresponding to actual physical objects (Peña‐Villasenin et al. 2020). Image processing depends on the focal length of the camera and the distortion of the lens. The major advantage of photogrammetry is its acquisition speed and model precision. However, it requires more processing time to run the algorithms that limit its applications.

Table 1.2 List of online sources for downloading 3D models.

Web page	Logo	Founder	Type	Access
Thingiverse		MakerBot Industries	Repository	Free
MyminiFactory		Romain Kidd, Sylvain Preumont	Marketplace	Both free and paid
Cults		Hugo and Pierre	Marketplace	Both free and paid
CGTrader		Marius Kalytis Dalia Lasaite	Marketplace	Both free and paid
Pinshape		Lucas Matheson, Nick Schwinghamer, and Andre Yanes	Marketplace	Both free and paid
YouMagine		Erik de Bruijn	Marketplace	Both free and paid
TurboSquid		Matt Wisdom, Tom Avgikos, David Avgikos, Andy Wisdom	Repository	Both free and paid
XYZprinting 3D Gallery		New Kinpo Group	Marketplace	Both free and paid
Threeding		Cveta‐Maria Partaleva, Stan Partalev, and Tony	Marketplace	Both free and paid

Table 1.3 Different scanning technologies.

Scanning mode	Scan range	Scanning principle	Description	Commercial scanners
Non‐contact	Short range	Laser triangulation‐based 3D technology	Projects a laser light source onto the surface of the object and determine the amount of deformed light reflected from the surface	Sense 3D scanner
Structured light‐based 3D technology	Uses trigonometric triangulation of the structured light (white/blue). It measures the deformed light pattern from the surface of object based on digital light processing (DLP) technique	EinScan, EinScan Pro 2X
Long range	Pulse‐based laser	Based on laser beam’s time of flight. The projected laser light is collected by sensor and time of travel between emission and reception provides surface details	Lidar 3D scanner
Phase shift laser	In addition to pulse‐based scanner, these systems modulate power of the laser thereby it allows comparison of the phase of the laser emitted and returned to the sensor	Lidar 3D scanner
Contact	Medium range	Coordinate measuring machine (CMM)	Involves measuring the degree of deformation of a probe by scanning several coordinate points on object’s surface	Altera SL bridge CMM
Arm‐based 3D scanners	Similar to CMM with additional provisions attachable 3D scanner unit for collecting large amount of points	Hexagon’s ROMER Absolute Arm scanner
Optically tracked 3D scanners	It uses a set of cameras to capture and track the location of scan in working space	Hexagon’s Leica Absolute Scanner and Creaform’s Metrascan 3D scanner