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How to Choose the Best 3D Scanner: Accuracy, Scan Volume, and Budget

3D scanning has an important place at the beginning and end of 3D fabrication workflows. Engineers, product designers, researchers, and more use 3D scanners as a faster and more efficient way to start constructing digital models, whether by incorporating existing designs via reverse engineeringdigitizing hand-sculpted clay designs, or referencing the exact shape of the human body.

After fabrication, 3D scanning can 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, it can be difficult to choose the scanner 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.


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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.

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What to Consider When Choosing a 3D Scanner

3D Scanner Price vs. Accuracy

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 2 stereolithography (SLA) 3D printer produces parts at a similar accuracy, and with a similar printable area to the scan volume of many desktop laser scanners.

Definition: Both structured light and laser scanners use projected light and an offset camera to triangulate points on a scan object. A laser scanner projects laser lines on the object, while structured light projects a focused grid from a digital projector. Structured light 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, scanners 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. 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 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 scanning technology. For example, the accuracy of handheld scanners depends on the distance to the subject and the quality of scan reconstruction, while desktop 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 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 scanners have an even wider range, and fill the niche for all objects that require precise measurement, but cannot fit in a desktop scanner.

Handheld 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 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 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 scanners.

Depth-sensing cameras,such as the Structure Sensor, Sense 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 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 3D model. Under ideal conditions, object detail captured by photogrammetry can rival a laser scanner.3 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 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.

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.

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.

Learn more about the 3D printer side of the equation: get to know stereolithography technology and see Formlabs advanced 3D printing materials for yourself with a free sample 3D printed part.

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