3D scanning Part A: Potential and possibilities

3D scanning techniques have found significant applications in various fields of activities including building, infrastructure, material science, manufacturing, automotive, aerospace, art and others. Their main uses involve 3D printing drawings acquisition, Quality Assurance, maintenance, conservation of rare objects, restorations, and others.

3D scanning technologies include various methodologies to acquire 3D images of existing objects. 3D scanning approaches can be categorized in the following categories, depending on various factors as described in Table 1.

Table 1: 3D scanning approaches depending on different attributes

Construction

Stationary – large size, bound to one location

Portable – small size, ‘bring-to-object’ principle

Scanning method

Contact – mostly stationary scanners with coordinate measuring   machines [CMM] and measuring arms

Non contact – laser scanners, optical scanners, X ray diffraction   scanners and other technologies

Specific scanning   principle

Optical – based on the photographic principle. An object is   photographed by various angles and the combination of 2D data lead to a 3D   image. Advantage: color acquisition

Laser – based on the triangulation principle. A laser beam falls onto   a surface and the time of flight is used to acquire the shape of the surface

Ultrasound – Based on the flight of time and triangulation like the   laser based scanners. Different in resolution [0.3 – 0.5 mm], less effective   that laser ones

X ray RTG – X ray diffraction and adsorption measurement lead to   accurate in depth measurements of the whole volume of an object. X ray offers   unique information on internal structure, layering, defects and other   important properties very important for specific applications such as 3D   printing, restoration and others

Mechanical – based on CMM and measuring arms, a portion of a surface   is scanned

Destructive – an object is skinned layer by layer to acquire all 3D   internal structure
Application areas

Reverse engineering – for object reconstruction and preservation

Quality control – acquisition of working behavior, requirements for   maintenance and replacement

Art and architecture – visualization of large buildings, restoration   needs, digitization of historical sites and artefacts, creation of learning   databases and platforms, creation of educational copies, creation of replicas   for exhibitions, partial modifications and others

Multimedia - Creation of educational material, creation of scientific   simulations, games and others

Medicine – reconstruction of human parts, visualization of human   parts, identification of disease states and others

Various other analytical techniques have been reported for structure acquisition and utilized with novel scanners. Among them the most important are:

  • -        Raman spectroscopy. Due to size requirements can only be applied to small scale objects
  • -        Atomic absorption. Based on bombardment of the scanned object with various small size atoms and subsequent measurement of absorption amounts and intensities
  • -        Small angle X ray scattering. Especially important for organic derived parts such as wood, bones, polymers [inhomogeneous and anisotropic materials]
  • -        Wide angle X ray scattering
  • -        Polarized light microscopy – for inhomogeneous and anisotropic materials
  • -        Second Harmonic generation imaging [SHG]
  • -        Fourier Transform Infrared Spectroscopy
  • -        Confocal Laser scanning microscopy [CLSM]
  • -        Serial focused ion beam/scanning electron microscopy (FIB/SEM)

Each of these methodologies presents advantages and shortcomings. Choice depends mainly on size, type, material and environment of the scanned object. Continuation of this article will provide analyses of various topics of interest.