Common 3D scanning terminology
If you are new to 3D scanning you may be confused with all of the terminology / industry jargon that is used. We thought we would write a brief article to help you better understand some of the key industry terms.
Definitions
Accuracy: How closely a measurement matches the actual value of the quantity being measured. This is often confused with precision. Precision is how close different measurements of the same target are to each other. When a scanner specification sheet talks about "Accuracy", they are almost always referring to the accuracy of a single scan. Volumetric accuracy, on the other hand, is the accuracy of several captures.
CAD model / CAD object: A feature-based, parametric solid model used in design engineering and manufacturing. It can be created in a CAD system, or reverse-engineering software package.
Frames: 3D surfaces captured during a scanning session, collectively constituting a scan. The scan rate varies with scanner type.
Fusion: Process that creates a polygonal 3D model. It effectively melts and solidifies the captured and processed frames or point-cloud surfaces.
Global registration: Algorithm that optimizes the relative positions of all frames using a single coordinate system.
Key frames: Frames used by the global registration algorithm. The algorithm selects them automatically to fully cover the surface of the captured object using as few as possible.
Mesh: The surface geometry of a 3D model; it comprises a series of linked polygons.
Model: The 3D object that results from the fusion operation.
Near and far cutting planes: Planes that limit the space in which the scanner is capturing 3D frames. The device will ignore everything that is closer than the near cutting plane or more distant than the far cutting plane.
Origin: The center of the coordinate system.
CAD primitive: A simple CAD model created and either fitted to a polygon model or positioned independently.
Resolution: The ability of a scanning system to capture detail in an object. With 3D scanning, resolution is the point to point distance on a mesh file or a dot cloud.
Scan: A sequence of frames captured in a single continuous movement of the scanner around an object or scene.
Supporting surface: A surface on which the object is resting (e.g., a table or the floor).
Targets: Stickers placed on the object being scanned to ease identification of the various regions. There are two types of targets: non-coded and coded. Unless the type is explicitly specified, the target is considered non-coded. Typically, a non-coded target is a round sticker that has a black ring with a white circle in the center; a coded target has a unique code ring that photogrammetry software can automatically recognize.
Tracking: Calculation of the scanner’s position in a coordinate system relative to the scene.
Further Reading
For further reading, see the following articles which go in-depth into Resolution and Accuracy which are the 2 most commonly misunderstood definitions with 3D scanning.
What is Resolution in a 3D Scanner and Why is it Important?
3D Scanner Accuracy and Resolution Basics
What is 3D Scanning?