3D scanning has an important place at the beginning and end of 3D fabrication workflows. Engineers, product designers, and researchers use 3D scanners as a faster and more efficient way to start constructing digital models, whether by incorporating existing designs via reverse engineering, digitizing hand-sculpted clay designs, or referencing the exact shape of the human body.
After fabrication, 3D scanning can support quality control and help to verify the accuracy of a 3D printed part, or, after the part has been used, a scanner can reveal how it’s performed—a scan of a deformed part can show you where to reinforce the design in the next revision.
With such a wide range of product options from handheld 3D scanners to desktop scanner, it can be difficult to choose the 3D scanning system that’s right for your application and budget. In this post, we explore several of the most important factors to consider when purchasing a 3D scanner.
3D Scanning for Reverse Engineering, Restoration, and Metrology
3D scanning and printing workflows can be applied to replication and restoration, reverse engineering, metrology, and more. Download our white paper or watch our webinar to explore these applications, and learn how to start using the technology to sophisticate your own design workflows.Download White Paper
What to Consider When Choosing a 3D Scanner
3D Scanner Accuracy vs. Price
3D scan accuracy varies considerably between technologies, and higher accuracy comes at a higher cost. The required tolerances of your final part can be a helpful guide for determining your accuracy requirements for a 3D scanner.
A comparison of the manufacturer-reported accuracy and price of 20 3D scanners available in 2018.
With accuracy in the range of 0.1 mm or better, laser and structured light scanners are a good fit alongside high resolution 3D printers. Formlabs Form 3 stereolithography (SLA) 3D printer produces parts at a similar accuracy, and with a similar printable area to the scan volume of many desktop laser 3D scanners.
Definition: Both structured light and laser 3D scanners use projected light and an offset camera to triangulate points on a scan object. A laser 3D scanner projects laser lines on the object, while structured light projects a focused grid from a digital projector. Structured-light 3D scanners can achieve higher accuracy than laser scanning due to the noise caused by laser speckle patterns.
Besides the accuracy between measured points and their actual location, 3D scanning systems also vary in terms of resolution, which is the distance between captured points at a given scan distance. This means that details on the scanned object that are smaller than the scanner’s resolution won’t be captured.
In general, structured light scanning provides the best resolution and accuracy, typically slightly higher than laser scanning technology. For some artistic use cases for 3D scanning you may need a lot of detail, while overall accuracy is less important—especially if you don’t require your part to fit precisely with other parts in an assembly. In these cases, photogrammetry, discussed in more detail later in this white paper, is an excellent low-cost option to explore.
Laser and structured light 3D scanners provide high accuracy, but reverse engineering also demands sufficient resolution to capture small surfaces. Photogrammetry can offer high resolution, but accuracy is usually inferior.
Accuracy can mean slightly different things depending on the manufacturer and 3D scanning technology. For example, the accuracy of handheld 3D scanners depends on the distance to the subject and the quality of scan reconstruction, while desktop 3D scanners have consistent accuracy within the constrained scan volume. If you are considering buying a 3D scanner for precise measurement, make sure to compare like to like.
3D Scanner Volume and Coverage
The area that a 3D scanner can capture varies significantly between scanners. Find a scanner that fits your size and resolution requirements without too much overhead, as cost typically increases with scan volume.
Handheld 3D scanners can be manually moved around the object and have fewer size constraints than desktop models. Most inexpensive handheld scanners can capture objects from the size of a basketball to an entire room. High-end handheld scanning solutions have an even wider range, and fill the niche for all objects that require precise measurement, but cannot fit in a desktop scanner.
Handheld 3D scanners are also able to capture objects near instantaneously, which makes them well-suited for taking human measurements (where the subject is not perfectly still) for ergonomics and medical applications.
Scanners may rotate the object to capture occluded areas. Red regions are occluded and will be missing in the scan. Areas with deep relief are difficult for a single axis turntable to fully capture due to occlusion.
If an area of the model can’t be seen by the scanner, it will cause a gap in the model. You can automatically repair small missing sections with most scan software to create a 3D printable model. However, repaired holes are rarely accurate to the original object.
Many 3D scanners use turntables to increase what the scanner can see. The sophistication of a scanner’s turntable affects how easily and completely the object is captured: some scanners have the ability to move the object around multiple axes, imaging the object from more angles. This feature is important when reverse engineering plastic parts with deep recesses and ribs, which are impossible to capture from a single angle.
Low-Cost 3D Scanning
The high cost of entry for laser and structured light 3D scanning systems can be prohibitive, but many lower-cost systems are available. Can low-cost scanning systems deliver enough performance for real world applications? Yes: Not all use cases require high accuracy, and low-cost scanners can have unique advantages, such as speed and scan size, that make them an interesting option in their own right.
There are three main categories of low-cost scanning systems: IR (infrared) depth-sensing cameras, photogrammetry, and entry-level desktop laser 3D scanners.
Depth-sensing cameras, such as the Structure Sensor, Sense 3D Scanner, and iPhone TrueDepth, project a field of dots in infrared to sample a 3D scene. Depth-sensing cameras are simple to use and are the least expensive 3D scanning option, but the accuracy and resolution of depth-sensing cameras is low, often larger than 1 mm, and fine details are usually lost. Large objects may be captured with depth-sensing cameras, but accuracy declines with increased distance from the subject and at steeper angles to the camera.
Photogrammetry uses a large set of photographs that are automatically analyzed to create a digital 3D model. Under ideal conditions, object detail captured by photogrammetry can rival a laser 3D scanner. Overall, geometric accuracy is usually worse due to the lack of fixed reference points for the camera’s position. Nonetheless, photogrammetry does not require any equipment besides a digital camera and software, which makes it an attractive option.
Both depth-sensing cameras and photogrammetry are a good solution for scanning large objects in order to create 3D printed scale models. They offer enough accuracy for capturing the shape of the human body, and can be used in workflows to create devices with customized ergonomics.
Several entry-level laser scanners are available using technology similar to higher-end systems, such as the Matter and Form and the EORA. These scanners are a great way to start replicating small objects at 1:1 scale. As one would expect, the accuracy of entry-level laser 3D scanners is lower than a high-end laser-based metrology scanner, but they can easily provide enough detail to replicate small decorative objects and figures where accuracy is not critical.
If you only have occasional 3D scanning needs, digitization services can scan your object, as well as perform CAD translation and accuracy inspection.
Flowchart: Choosing the Best 3D Scanner for Your Application
Use this flowchart to determine what scanner you need based on accuracy, scan volume, and budget.
How Does 3D Scanning Complement 3D Printing?
A 3D scanner expands the capabilities of a 3D printer, allowing you to replicate the shape of almost any object. Together, the two technologies create a powerful, digital workflow that can simplify and sophisticate processes in a range of industries.
The output from a 3D scanner is a mesh of triangles representing the surface of an object at a real-world scale. In some cases, the scan can be used directly to replicate objects without any CAD work.
A hybrid workflow can also be powerful, where solid CAD models are combined with scanned 3D models. Customized ergonomics capture a physical imprint of a part of the human body, and integrate them with a mechanical design.
3D scanners are also valuable tools for measuring the accuracy of manufactured objects. Many factors affect 3D print accuracy, and metrology-grade 3D scanners provide a clear picture of how a material performs for demanding applications.
3D Scan to 3D Print: Rapid Reverse Engineering for Machine Restoration, Assembly Jigs, and Aftermarket Products
Watch this webinar for a detailed look at how to start using 3D scanning to improve part design and production when paired with reverse engineering CAD and 3D printing.Watch the Webinar Now
Building a Digital Workflow With 3D Scanning and 3D Printing
3D scanners and 3D printers are essential parts of digital workflows across industries. Download our white paper or watch our webinar to get a detailed look into how to start using 3D scanning to improve part design and production and how, paired with 3D printing, scanning technology workflows can be effectively applied to a variety of workflows in engineering, product design, and more.
Request a Sample Part
In order to start generating useful, 3D printable models from a 3D scanner, you will need to know how to work with their output. Learn how to approach converting a scan to an intelligent, 3D printable CAD model with reverse engineering.