Stationary vs Handheld 3D Scanners: What are the Differences?
From engineers to historians, stationary and handheld 3D scanners are used by an ever-growing list of professionals to help make their work easier or to do what was previously impossible, or prohibitively complex or costly.
How 3D Scanners Work
There are a variety of 3D scanning technologies. But they all fall into one of two categories, based on how they capture the data.
Single Image Capture
Tracked 3D scanners and structured light scanners take single images or scans from different positions around the object being scanned. The scanning head must be stationary as each image is captured. The images are digitally stitched together to create the 3D scan.
Continuous Image Capture
CMM 3D scan arms and portable handheld scanners capture multiple images continuously until a full 3D image of the scanned object is complete. CMM scan arms must remain stationary in a fixed location.
The Differences Between Stationary & Portable 3D Scanners
Stationary 3D Scanners
Many stationary 3D scanners are portable. But, generally speaking, the 3D sensor, and/or the sensor tracking device remains in stationary during a scan.
Stationary 3D Scanner Categories
There are three main categories of stationary 3D scanners.
- Structured-light 3D Scanners – These scanners house one or two 3D scanning sensors and an LCD or laser beam projector. A pattern of light is cast by the projector onto the object being scanned. The scanning sensor records and processes the differences in the distortion of each light pattern for each scan.
Structured light scanners produce very high-resolution scans. But they need to capture a lot of data during each scan to do so. This can make it a more time-consuming process compared to other scanning methods.
- Coordinate Measuring Machine (CMM) Scanners – CMMs with movable scanner arms are anchored in a fixed position. The 3D scanner is mounted on the end of the articulated arm. This allows the scanner to be moved around the object being scanned.
Fixed-probe or touch-trigger probe heads may be mounted on the scanner arm. This makes it possible for CMMs to integrate 3D scans and metrology probes in the same project. However, CMM scanner arms must be anchored on a fixed surface. This limits where they can be located and makes them vulnerable to vibrations and other issues affecting scan quality.
- Tracked 3D Scanners – These scanners use an external optical tracking device to track the location of the 3D scanner as the scan is performed. So there is no need for a physical link between the scanner head and the tracking device, (as needed with a CMM with a movable arm).
Being detached from the tracking device offers tracked 3D scanners more freedom of movement versus CMM scanner arms. They are also capable of producing highly accurate and precise scans.
Handheld 3D Scanners
Handheld 3D scanners combine the two scanning sensors and a white-light or laser-pattern projector into a single, handheld unit. The dual cameras allow the unit to track the position of the scanner in relation to the object being scanned.
Handheld scanners are easily transported to different locations and the scanning process is usually easier than stationary scanners. They can be used to scan objects as large as small airplanes and even sections of buildings. Positioning errors can occur when scanning larger objects, but there are ways, including photogrammetry and positioning targets, to compensate for the errors.
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