Scanners & Scanning

As we have seen during the introduction, the first step to reverse engineer a product is through scanning with the help of 3D scanners. Early eras have seen the painstaking task of obtaining dimensions of an existing product. These methods were time consuming and needed attention to details from the very first stage.

However, with the rapid development in the scanning technology, the inception of a product has caught speed and the chances of errors have reduced dramatically which has made 3D scanning and measurement an important part, starting from design stage to inspection stage.

3D laser scanning is the technology to capture a physical object’s exact size and shape using a laser beam to create a digital 3-dimensional representation of the same. 3D laser scanners create “point clouds” of data from the surface of an object.

We will go through point clouds in later sections.

3D Scanning Technology

3D laser scanning efficiently takes the measurements of contoured surfaces and complex geometries which require huge amounts of data for their accurate description because doing this with the use of traditional measurement methods is impractical and time consuming. It creates accurate point cloud data by acquiring measurements and dimensions of free-form shapes.

The basic working principle of a 3D scanner is to collect data of an entity. It can either be:

  • an object
  • an environment (such as a room)
  • a person (3D body scanning)

In reverse engineering, laser scanner’s primary aim is to provide a lot of information about the design of an object which in the later stages gets converted to 3D CAD models, considering the compatibility of 3D scans and Computer Aided Design (CAD) software. 3D scans are even compatible with 3D printing which requires some specific computer software.

3D scanning technologies varies with different physical principles and can be classified as follows:

  • Laser triangulation 3D scanning technology: In this category, the laser scanner projects a laser beam on a surface and measures the deformation of the laser ray.
  • Structured light 3D scanning technology: This technology acquires the shape of a surface by measuring the deformation of a light pattern.
  • Photogrammetric technology: It is also known as 3D scan from photography. It reconstructs an object from 2D to 3D and has specific computational geometrical algorithms for the task.
  • Laser pulse 3D scanning technology: This unique process collects geometrical information by evaluating the time taken by a laser beam to travel between its emission and reception.

Contact based 3D scanning technology: This process requires contact between the probe and the object, where the probe is moved firmly over the surface to acquire data.

Types of scanners

Apart from scanning technologies, there are various types of 3D scanners. Some are built for short range scanning while others are ideal for medium or long range scanning. The built and usage of specific scanners hugely depend upon size of the object to be scanned. The scanners used for measuring small objects vastly differ from the ones that are used for large bodied objects, such as a ship.

Here is a brief summary of types of 3D laser Scanners:

  1. Short Range 3D scanners: Short Range 3D scanners utilize either a Laser triangulation technology or Structured Light technology.
  1. Laser based 3D scanners: Laser scanners work by projecting laser a beam or multiple laser beams on an object and capturing its reflection with sensors, which are located at a fixed distance from the scanners.
  1. Structured light 3D scanners: These are also known as white light scanners. However, most structured scanners use blue or white LED light. The light pattern usually consists of a certain geometrical shape such as bar or block or any other shape, which is projected onto the object. The sensors consider the edge of the pattern to determine the 3D shape of the object. Blue or white light scanners are generally used to obtain outward dimension.
  1. Medium and Long range scanners: Long range 3D scanners are used for large objects such as buildings, ships, aircrafts, and military vehicles. These scanners rotate and spin a mirror which reflects the laser outward towards the object or areas to be 3D scanned.
  1. Arm based scanners: Arm based scanners are very useful when measuring small minor parts, as it can be maneuvered by attaching it to the arm and is generally portable.

Arm-based scanner

Benefits of 3D Laser Scanners

3D scanners have contributed a lot over the years and needless to say, it comes up with many benefits. Some of them are as follows:

  • Able to scan tough surfaces, such as shiny or dark finishes.
  • This is strictly for the handheld or other portable scanners. But given their importance, it is safe to say that the portability of scanners has played a great role in easing up engineering.
  • The scanning technology has made it possible to capture millions of point in a considerably less time.
  • Scanners are less sensitive to changing light conditions and ambient light.
  • Scanning of complex contours and geometrical figures have become more convenient with the invention of groundbreaking scanning technologies.
  • Nowadays, laser scanners have become so diverse that they are produced depending upon variety of projects or the objects to be scanned.