AlfaTest presents its vision and classification of 3D Scanning.

3D scanning

3D scanning is the process of analyzing a real-world object or environment to collect data on its shape and possibly its appearance (i.e. color). The collected data can then be used to construct so called digital three-dimensional models.

In modern engineering, the term `laser scanning’ is used to describe two related, but separate meanings. Firstly, more general, it is the controlled deflection of laser beams, visible or invisible. Scanned laser beams are used in laser printers, in laser shows, in Laser TV, and in barcode scanners.

Secondary, more specific, it is the controlled steering of laser beams followed by a distance measurement at every pointing direction. This method, often called 3D object scanning or simpy 3D laser scanning, is used to rapidly capture shapes of objects, buildings, and landscapes.

According to the Allied Market Research, significant factors that impact the growth of the global 3D scanning industry include ongoing technological advancements in 3D scanning in addition with surge in need for highly accurate 3D scanning.

Moreover, growth in need to capture large volumes of 3D data for modeling and analysis is expected to drive the market opportunity. However, dependence of market growth on non-3D businesses coupled with high price of high-resolution 3D scanners acts as a prime barrier for early adoption, which therefore hampers the growth of the market.

On the contrary, growth in 3D printing market generates demand paired with structured light-based 3D scanning, which is expected to offer potential growth opportunity for the 3D scanning market during the forecast period.

There are many classifications and categories of 3D scanners. We at AlfaTest see a global 3D scanning market consisting of the following scanning technologies:

Contact Scanning (Coordinate Measuring Machines – CMM)
Time of Flight (ToF)
Laser Scanning (Triangulation)
Structured Light
Volumetric (Computed Tomography)
Photogrammetry

CONTACT SCANNING (COORDINATE MEASURING MACHINES i.e. CMM)

This 3D scanning method involves the physical contact of a probe onto the surface of the object being scanned. First, the object is firmly held in place so that it does not move. Then, the touching probe is moved all over the object in order to collect the details of the object and all the 3D information that is necessary to create a digital file.
The disadvantage with contact 3D scanning is its obviously slow speed. Running the touching probe through all sections of an object in order to collect all the 3D information takes time. Tag: Jointed arms.

APPLICATION (chiefly):
Quality control; Deformations or damages control; Highly accurate 3D modelling

OVERALL ADVANTAGE:
Accuracy up to 0.0001 mm

OVERALL DISADVANTAGE:
Timing; Sensitive to vibrations, etc; Stationary

APPROX COST (for instance):
Used: € 20.000-50.000

REPRESENTATIVE VIDEO (to demonstrate): Link 1; Link 2

TIME OF FLIGHT (i.e. ToF)

Basically, is a method for measuring the distance between a sensor and an object, based on the time difference between the emission of a signal and its return to the sensor, after being reflected by an object. Tag: Light Detection and Ranging (LiDAR); Phase shift.

APPLICATION (chiefly):
Large structures, such as buildings and other geographical features. In addition, architecture, construction, and building facility management industries.

OVERALL ADVANTAGE:
Large distances use; Scanning in darkness (IR)

OVERALL DISADVANTAGE:
Acquisition speed; Tolerances > 2 mm; Surface cannot be reflective or transparent; Light speed affected by environment; Multiple scans needed

APPROX COST (for instance):
Used: € 15.000-60.000

REPRESENTATIVE VIDEO (to demonstrate): Link 1; Link 2; Link 3

LASER SCANNING (i.e. TRIANGULATION)

By casting a laser beam upon the object being scanned, a camera is able to record where the beam and object intersect. Knowing both the angles of the laser beam and camera therefore makes it possible to know the precise location of the laser dot that is hitting the object.

In most cases a laser stripe, instead of a single laser dot, is swept across the object to speed up the acquisition process.

The position can be determined by the scanner using reference features on the surface being scanned. Tag: Adhesive targets; Laser tracker.

APPLICATION (chiefly):
Quality control; Reverse engineering; 3D printing

OVERALL ADVANTAGE:
Low price of stationary scanners; Acquisition speed; Accuracy 0.01 mm

OVERALL DISADVANTAGE:
Surface cannot be reflective or transparent; Limited range; Time for applying positioning targets

APPROX COST (for instance):
New: € 20.000-30.000

REPRESENTATIVE VIDEO (to demonstrate): Link 1; Link 2

STRUCTURED LIGHT

Structured light 3D scanners project an image with a pre-determined pattern on the subject. Depending on the features of the subject, the pattern will then be distorted in a number of different ways. A camera records the image of the projected pattern and uses the data on the distortions to calculate the dimensions of the individual features.

APPLICATION (chiefly):
Quality control; Reverse engineering; 3D printing

OVERALL ADVANTAGE:
Accuracy up to 0.001 mm; Acquisition speed; Relatively low cost

OVERALL DISADVANTAGE:
Surface cannot be reflective or transparent; Need for dim lighting or total darkness

APPROX COST (for instance):
New: € 10.000-20.000

REPRESENTATIVE VIDEO (to demonstrate): Link 1; Link 2

VOLUMETRIC (i.e. COMPUTED TOMOGRAPHY)

For example, the object is placed on a turntable in the middle of the CT scanner. The X-ray tube emits X-rays that penetrate the object. A detector receives the rays and creates a 2D X-ray section image.
Then the turntable is rotated minimally, and the scanner generates another X-ray image.
These 2D sectional images are then combined by the computer to form a 3D model. This process is called: “Creation of a volume graphic”.
MRIs (magnetic resonance imaging) use radio waves and CT (computed tomography) scans use X-rays. MRI is for softer tissue.

APPLICATION (chiefly):
Medical industry; Industrial NDT; Security

OVERALL ADVANTAGE:
Accuracy ≤0.005mm; External and internal inspection

OVERALL DISADVANTAGE:
Can only penetrate certain materials. The denser the material, the more difficult it is for the CT scanner to create a 3D model. As for lead, it is almost impossible for X-rays to penetrate it; Surely price

APPROX COST (for instance):
New: $ 285.000-2.100.000

REPRESENTATIVE VIDEO (to demonstrate): Link 1

PHOTOGRAMMETRY

The technology takes multiple images, taken at different positions, and triangulates points in these images in order to figure out the location of them in a three-dimensional space.