What Is 3D Scanning?
Before starting 3D printing, a 3D model is always necessary. And though these can be acquired in different ways, including by downloading a model from dedicated platforms or designing one using one of the many different 3D modeling software on the market, it is also possible to create a model from a real-life object. How? By using 3D scanning.
Defined as the “process of analyzing a real-world object or environment to collect three-dimensional data of a shape or possibly appearance,” 3D scanning has grown increasingly popular over recent years, whether with an actual scanner or even specifically designed apps on a smartphone. The advantage it has over more traditional modeling is that it can perfectly capture an object digitally, allowing it then to be 3D printed.
What’s the Process?
As you may expect, the first step of any 3D scanning process is having a tool with which to do it. This most often is a 3D scanner. These come in a variety of forms, with models for both professionals and amateurs, to suit different needs. Some common hardware includes portable scanners, desktop scanners and even full body scanners. Furthermore, users can decide between long-range scanners (used to capture the geometry of large objects like buildings) or short-range 3D scanners (most suitable for smaller objects that may need a higher level of accuracy).
All 3D scanners use a type of sensor, whether physical probe, laser or light, to measure the distance between a camera and an object. This is used to identify 3D points using triangulation, the process of determining the location of a point by forming triangles to the point from known points. These in turn form a point cloud which is then meshed, connecting the dots of the point cloud out of a collection of vertices and faces with varying complexities depending on a user’s needs. The meshed cloud becomes the 3D model made up of surfaces. Generally, the main steps for scanning are data capture, data processing and refinement and exportation. Additionally, to make the file suitable for 3D printing, it is necessary to have the point cloud be read by specific mesh reading software, take for example MeshLab.
Although it can be easy to think that scanning is as easy as turning on the scanner and capturing the object, that is not actually the case. There are different considerations that should be kept in mind to ensure a successful scan. These will not all be used for every scan, but many are essential steps.
First, 3D scanners should be calibrated to ensure accuracy. Then, you should ensure that the object in question is in suitable light, if it uses a visible line of laser light for example outside scanning could be possible, but any scanner using invisible, infrared light will need to be used indoors. An additional consideration is whether to use markers, which can be used to help create a seamless model. Lastly, shiny or transparent objects will need to be coated with a matting spray to ensure the scanner can be used.
Different Types of 3D Scanning
Laser 3D Scanning
Laser 3D scanning is one of the most popular 3D scanning technologies and as such is the one that you may most often encounter in diverse applications including land surveying, forensics and heritage preservation. How it works is that, as the name suggests, a laser light is used to get the digital representation of the object with a laser dot or line projected on an object measuring the distance to the surface of the object. This data can then be converted into a triangulated mesh. Scanners using this technology are known for their ability to measure extremely fine details and capture free-form shapes in highly accurate point clouds.
Structured Light Scanning
Structured light scanning, similarly to laser 3D scanning, also uses the principle of triangulation to create the 3D model of the object. However, this technology works by using a series of parallel patterns that are projected onto the object via a light source, for example grids or stripes. Cameras then are able to capture the deformation of this pattern in order to determine the shape of the object.
Photogrammetry
In contrast to laser 3D scanning which uses lasers and distances to create a 3D model, photogrammetry is based on a multitude of photographs which, when taken together, can extrapolate the design of the object from different points of view. Though significantly less accurate than laser scanning, the technology is much more accessible as it can often be done with even just a phone. If good photogrammetry software is used as well, you can anticipate a decent result. Suitable if accuracy is less important for your design as well as for large objects or scenes. And a number of different photogrammetry software are available today for all levels.
Others
It should be noted, that the three above, while the most used with 3D printing, are not the only scanning technologies available. For example, in the healthcare sector, one of the most commonly used scanning processes is computerized topography, or CT scans, and which are useful when using AM technologies to create surgical models. Additionally, contact-based 3D scanning technology which uses touch probes to determine the object, can be useful for objects that will move during scanning. Finally, laser pulse-based 3D scanning or time-of-flight scanning, creates scans using the speed of light and sensors by measuring the time it takes for a cast laser to reach an object and come back via reflection.
Benefits of and Applications for 3D Scanning
Now that you have a basic understanding of what 3D scanning is and how it works, the next question to answer is why and when to use it? As mentioned, 3D scanning can be used in a wide variety of applications and sectors. Some of the most commonly mentioned are manufacturing (notably for our purposes with 3D printing), architecture, heritage, healthcare and even entertainment.
3D scanning will be a good choice for those who need to create a 3D model quickly and accurately representing a real-life model. For example, 3D scanning is often used for the creation of digital twins or in reverse engineering. With digital twins, 3D scans allow for a completely accurate model that can be tracked and engaged with in real time. Meanwhile, reverse engineering is often used for the creation of spare parts, something for which additive manufacturing is particularly well-suited.
But regardless of how you wish to use 3D scanning, it is undeniable that it is extremely interesting when combined with 3D printing. By bringing real-life models to the flexibility and adaptability of 3D printing, parts can be made that could never even be dreamed of with more classic technologies. Additionally, although many think of 3D scanning purely for the creation of CAD models, it can also be used for quality control after a part has been created, an increasingly important step for 3D printed parts given the industrialization of the technologies.
