Table of content
- Laser triangulation 3D scanning technology
- Structured light 3D scanning technology
- Photogrammetric technology
- Laser pulse 3D scanning technology
- Computerized Tomography (CT scan)
- Contact-based 3D scanning technology
As we have seen during the introduction, the first step to reverse engineering 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 detail from the 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, making 3D scanning and measurement a vital part, starting from the design stage to the 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 produce “point clouds” of data from the surface of an object.
3D Scanning Technology
3D laser scanning efficiently takes the measurements of contoured surfaces and complex geometries, requiring vast amounts of data for accurate description. Doing this using traditional measurement methods is impractical and time-consuming. Acquiring sizes and dimensions of free-form shapes creates precise point cloud data.
The basic working principle of a 3D scanner is to collect an entity’s data. It can either be:
- an object
- an environment (such as a room)
- a person (3D body scanning)
In reverse engineering, a 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, requiring specific computer software.
3D scanning technologies vary 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 involves projecting structured patterns of light on an object and acquiring a surface’s shape by measuring the light pattern’s deformation.
Photogrammetric technology: It is also known as a 3D scan from photography. It reconstructs an object from 2D to 3D and has specific computational geometrical algorithms for the task. Photogrammetry is cheap, precise, and used to scan large objects such as buildings and stadiums.
Laser pulse 3D scanning technology: This unique process collects geometrical information by evaluating the time a laser beam takes to travel between its emission and reception.
Computerized Tomography (CT scan): A widely used technique in the medical sector, CT scan is generally used to scan images of the human interiors. CT scans consist of scanning a part and taking a series of 2D images of various sections with X-rays. The 2D images are later superimposed on each other to imitate a 3D model.
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 building and usage of specific scanners hugely depend upon the object’s size to be scanned. The scanners for measuring small things vastly differ from those used for large-bodied objects, such as ships.
Here is a summary of the types of 3D laser Scanners:
Short Range 3D scanners: Short Range 3D scanners utilize either a Laser triangulation technology or Structured Light technology.
Laser-based 3D scanners: These scanners employ trigonometric triangulation to capture a 3D object as millions of points. Laser scanners work by projecting a laser beam or multiple laser beams on an object and capturing its reflection with sensors located at a fixed distance from the scanners. Laser scanners come in various designs such as handheld portable units, arm-based, CMM-based, long-range, and single-point long-range trackers.
Structured light 3D scanners: These are also known as white light scanners. However, most structured scanners use blue or white LED lights. The light pattern usually consists of a geometrical shape such as a bar, block, or other shape 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 dimensions. Medium and Long range scanners: Long-range 3D scanners are used for large objects such as buildings, ships, aircraft, and military vehicles. These scanners rotate and spin a mirror which reflects the laser outward towards the thing or areas to be 3D scanned.
Arm-based scanners: Arm-based scanners are handy when measuring small minor parts, as they can be maneuvered by attaching them to the arm and is generally portable.
Benefits of 3D Laser Scanners
3D scanners have contributed a lot over the years; needless to say; they come up with many benefits. Some of them are as follows:
Able to scan harsh surfaces, such as shiny or dark finishes.
This is strictly for handheld or other portable scanners. But given their importance, it is safe to say that the portability of scanners has played a significant role in easing up engineering.
The scanning technology has enabled it to capture millions of points in less time.
Scanners are less sensitive to changing light conditions and ambient light.
Scanning of complex contours and geometrical figures has become more convenient with the invention of groundbreaking scanning technologies.
Laser scanners have become so diverse that they are produced depending upon various projects or the objects to be scanned.
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