Các thuật ngữ trong 3dcanning
Common 3D Scanning Industry Terms
Many of our customers are new to 3D scanning or 3D laser scanning or are simply curious! We’ve compiled a glossary of common industry terms to help you learn more about the unique terms and phrases we use to describe the services, products, and valuable tools and techniques associated with 3D scanning.
- 2D Drawing – A 2D representation of a CAD model typically complete with
measurements and dimensions for use in many manufacturing processes.
- 3D Laser Scanner – A 3D scanning device that uses a laser to reflect off
the part and triangulate with a camera lens, allowing the scanner to determine and create
XYZ coordinates. The scanner then uses these points to form a 3D digital model of the part.
- 3D Modeling – 3D modeling refers to the creation of three-dimensional objects that are
defined mathematically and geometrically (i.e. a circle extruded to a certain value to create a cylinder
defined by its location, radius and length). 3D modeling can be aided by the use of scan data
(see Reverse Engineering).
- 3D Scanner – 3D scanners come in many forms, but the purpose of every one of them is to
capture the shape, and sometimes color, of real-world physical objects or environments. This captured data
is typically stored as a list of xyz-coordinates in a point cloud file. 3D scanners can be categorized as
contact (CMM arms) or non-contact (white light, 3D laser scanners, or stereo-vision based). Some can even
capture internal features. “3D scanner” is sometimes mispelled as “3D scaner”.
- 3D Scanning – 3D scanning is the fast and accurate process of using a 3D scanner to
capture and convert physical objects into digital 3D data.
- Accuracy – The accuracy is the closeness of a measurement to the actual feature.
The opposite of accuracy is uncertainty, which is an inverse perspective of the same value. See Uncertainty.
- Alignment – The process of aligning two objects in a common coordinate system. Commonly
refers to aligning scan data to reference objects in inspection applications.
- As-Built – An object’s real-world condition and appearance.
- As-Designed – How the object was originally designed, usually in a CAD environment.
- Auto Surfacing – Wrapping a patch-work quilt of freeform NURBS surfaces around scan data,
quickly and automatically generating surfaces.
- CAD – Computer Aided Design. CAD is a standard term defining a group of software that
aides in design. CAD software is what is used for 3D modeling and to create 2D drawings. It is typically used in
manufacturing or other engineering disciplines. For example: An engineer designs in SolidWorks, Pro-E, AutoCAD, CATIA,
or Unigraphics; all of which are CAD or CAE programs. Often confused with CAE.
- CAI – Computer Aided Inspection. CAI is a set of technologies that convert designs into
data used to run the inspection process.
- CAM – Computer Aided Manufacturing. CAM is a set of technologies that convert designs into
data used to run the manufacturing process.
- CAQ – Computer Aided Quality Assurance / Inspection / Control. See CAI.
- Class A – The most simple mathematical curve or surface that can describe a shape. Example:
A customer requests a “Class A” IGES surface when he needs a super smooth surface typically used in aerospace
or automotive applications.
- Color Map – A color plot visually representing deviations from actual to theoretical.
Example: A customer requests a colormap inspection when needing to compare an as-built object to its
as-designed CAD data.
- Computational Fluid Dynamics (CFD) – Computational fluid dynamics is the study and analysis
of fluid and gas flow in a system with the use of numerical methods algorithms. Computers are required to handle
the millions of calculations involved in CDF analysis with applications such as aerodynamic (wind tunnel) and
hydrodynamic testing. It is common to use a 3D scanner to capture object surface data for use in such tests.
- Datum – A certain feature such as a point, line, plane, cylinder, etc. that can be
used to establish the location or geometric relationship of another feature.
- Decimation – Decimation in general refers to reducing the number of samples in a
population. In 3D scanning, decimation usually refers to lowering the number of triangles on a surface
without distorting the detail or color. Decimation is used when there are a large number of unnecessary
- Degrees of Freedom – Describes the numbers of directions of movement and refers to how
the position and orientation of an object is described relative to a coordinate system. In 3D scanning
it usually consists of three linear translations (X, Y, and Z) and three rotations about the three
axes (pitch, yaw, and roll).
- Deviation – As typically applied to 3D scanning, deviation refers to the difference
in the size and shape of a manufactured part versus its design specifications. Deviation is easily
discovered by quality inspection with the use of color maps and cross-sectional analysis found in CAI
- Digital Archiving – Storing data digitally. Objects can be scanned and processed
for digital archiving purposes, reducing the need to store physical parts in locations such as a warehouse.
- “Dumb” IGES – “Dumb” IGES is a term used to refer to any IGES, STEP or
other surface file format. Though technically a mathematical model, it is considered “dumb” because the data
contains no parametric history of the model; it is simply a surface that cannot be intelligently edited.
Ex: If a cylinder is modeled in 3D and exported in .IGES file format, the cylinder cannot be edited by
changing its radius or extrusion length.
- FEA – Finite Element Analysis. When a surface model is subjected to various tests
to determine or establish its integrity under specified conditions.
- FEM – Finite Element Model. The creation of a mathematical surface description of
an object resulting in a model ready for analysis.
- Fillet – A surface that connects two or more faces. This surface is usually an arc.
- Geometric Dimensioning & Tolerancing (GD&T) – Geometric Dimensioning and Tolerancing
is a standard used to define the nominal geometry of parts and assemblies, to define the allowable
variation in form and possibly size of individual features, and to define the allowable variation between features.
- Hybrid Surface Model – An IGES or STEP surface that usually combines auto-surfaced
features with typical 3D modeling operations. Hybrid models are “dumb” because the data contains no parametric history
of the model; it is simply a surface that cannot be intelligently edited. Such models have areas that are not ideally
mathematical in nature, and instead are composed of NURBS surface estimates of the scan data.
- IGES – Initial Graphics Exchange Specification / System is a standard mathematical
surface file, used for over 25 years in most CAD systems to mathematically represent physical data.
It is the most common format for exchanging CAD data between software programs. See also STEP.
- Inspection – See Quality Inspection.
- Laser Scanner or Laser-Line Scanner – See 3D Laser Scanner.
- Legacy Part – A part that is already created or existent in the customer environment.
As typically applied to 3D scanning, legacy parts usually do not have CAD data.
- Median Part Verification – When several of the same parts are scanned and the resulting
data is averaged and used to create one representative 3D model. Median part verification is used to minimize the effect
of manufacturing defects on the resultant model.
- Merge – Combining two or more scan data sets into one larger data set.
- Mesh – See Poly-mesh.
- Noise – Noise is the existence of extraneous recorded data within a point cloud. It
can be caused by an object obstructing the sensor or ambient light and reflections into the sensor
during the data capture process.
- NURBS – Non Uniform Rational Basis, or Bézier Spline. It is a mathematical model
commonly used for generating and representing curves and surfaces that cannot be decimated in a
uniform manner. It can also be a surface created by two or more b-splines. First developed mid-century
but didn’t arrive on the desktop until 1989.
- Organized STL – Mesh data consisting of point cloud data with mathematical point
spacing based on surface data. An organized STL of a cube would consist of 8 points (1 for each corner).
- Parametric Model – A data set that retains the history of how it was designed, so
that modifications update all downstream features. Exchange of such models is supported by IGES.
SolidWorks is a software program that is popular for creating and modifying parametric models.
- Performance Surfaces – Surfaces that are affected by certain aerodynamic and
hydrodynamic forces. The shape of these surfaces is usually key to the performance of the object.
- Photogrammetry – The process of taking precise measurements by using digital
pictures and coded targets. For 3D scanning purposes, the coded targets and reference markers in
the picture frame serve as anchor points where scans can be aligned to. Photogrammetry ensures
extremely accurate scan data. Also see Videogrammetry.
- Precision – The repeatability of performing a measurement.
- Point Cloud – A point cloud is the computer visualization of the XYZ coordinates
that describe a physical object or environment. Each point represents an actual point on the object
or in the environment, and collectively describes its shape and measurements. Points can be captured
individually, such as with a CMM, or thousands at a time, such as with a 3D laser scanner that
captures multiple point sets from different perspectives that can be merged into a cloud. Point
clouds are typically represented by an unorganized STL file. Synonomous with raw scan data.
- Poly-mesh – A polygonal model that is used in 3D computer graphics. A mesh is a
visualization of point cloud data that basically connects the dots to form triangles. See also STL.
- Quality Inspection – The process of evaluating a physical part and comparing it to
the design specifications that are described in the object’s CAD file. Inspection is an “as built”
vs “as designed” comparison. See also Deviation.
- Rapid Surfacing – See Auto Surfacing.
- Reference Markers – Adhesive backed retro-reflective dots used in 3D scanning
applications to create reference points and help align pieces of scan data. Some scanners, such as
the Handyscan 3D, use reference markers to position themselves in space, eliminating the need for
attachment to a CMM arm or a fixed focal length.
- Registration – The process of aligning two data sets together based on known
coordinates in each. Registration enables the alignment and integration of two of more point cloud
data sets to complete larger models that must be captured in multiple scans.
- Rendering – A graphical representation of a computer model. It is often used to
describe the visual output of CAD and Modeling software. By rendering a computer model, you can often
add characteristics and effects to its surfaces and features.
- Resolution – The spacing of points in a grid. The higher the resolution, the more
data that will be captured. Likewise, the lower the resolution, the “flatter” the detail.
- Reverse Engineering – Reverse engineering broadly refers to analyzing and dissecting
something with the goal of recreating it. In 3D scanning, reverse engineering typically means the
process of measuring an object using a 3D scanner and then creating CAD data that reflects its original
design intent. This can also be done by using rulers, calipers, or a CMM. Reverse engineering is sometimes
referred to as Reverse Modeling.
- Reverse Modeling – See Reverse Engineering.
- Scan – Measuring the part, capturing data, and transferring the measured points to
the computer. It also refers to the computer file that is based on the physical part, i.e., xyz coordinates
that represent physical measurements taken by the scanner.
- Shell – A particular operation for CAD. In 3D scanning, involves the creation of an
offset surface from the original surface in order to create thickness.
- Shrink Wrap Surface Model – Refers to the way in which 3D scanning software like Geomagic,
RapidForm, and Paraform fit mathematical IGES surfaces to a “physical” scan. Similar to how plastic shrinkwrap
“shrinks” down onto a part being “wrapped”.
- Stereo Vision – A method of capturing three dimensional data based only on cameras. An algorithm
of stereo vision involves receiving inputs from two or more different cameras oriented at different angles and
analyzing the differences between the images to obtain 3D information. This 3D information is easily read as a
3D point cloud.
- STEP – Standard for the Exchange of Product Model Data is a comprehensive ISO data standard
(ISO 10303) for the exchange of object descriptions between systems. STEP is a file format that is usually
interchangeable with IGES.
- STL – Standard Tessellation Language. STL is a special internationally recognized file format
that stores XYZ coordinate measurements and their normals. Gives the added functionality beyond XYZ coordinates
enabling visualization of a part’s “front” and “back.” STL is the standard file format for rapid prototyping,
and is used in reverse engineering. See Organized STL and Unorganized STL.
- Surface – Refers to the part being scanned or to the computer file from the scanner. It typically
means a computer file in IGES format. See also IGES.
- Surfacing – The process of defining or creating a surface on a CAD model. Typically refers to
converting a polygonal representation of an object to a NURBS or other mathematical representation. It is the
process of converting physical based 3D data to mathematical based 3D data. See also Auto Surfacing and Reverse
- Talc – Talc powder is typically applied to translucent, reflective, or black/near-black
objects during the 3D laser scanning process in order to improve the ability of the laser scanner to
capture data. Talc powder is predominantly white and is usually applied with a pen or an aerosol spray.
Talc can easily be wiped off and cleaned, and generally will not damage an object.
- Targets – See Reference Markers.
- Tessellation – Generally refers to filling a surface plane or surface with shapes that
create no gaps or holes. In 3D scanning, this concept applies to wrapping a mesh around a CAD body. A jigsaw
puzzle is a great real world example of a collection of tessellated shapes.
- Time of Flight – 3D laser scanners that calculate measurements based on the time it
takes for the laser beam to detect a surface and report back.
- Touch Probe – A Coordinate Measuring Machine (CMM) that requires physical contact
with the part to measure it.
- Triangulation – Using trigonometric functions to calculate measurements, used in
certain types of 3D laser scanners to determine point locations based on transmission and reflection
positions of the laser beam. In 3D modeling, triangulation also refers to the generation of triangles
out of point cloud data in creating 3D surfaces.
- Uncertainty – The uncertainty is the quantity of how much a measurement is
unknown compared to the actual feature. Uncertainty is the inverse perspective of accuracy, which is defined
as the closeness of a measurement to the actual feature. The uncertainty essentially describes how much of
a measurement is uncertain. See Accuracy.
- Unorganized STL – Mesh data based on point cloud data taken from a scan. Point
spacing is based off the number and resolution of scans and not dependant on the shape or features
of the object being scanned.
- Videogrammetry – The process of taking precise measurements by using video images
taken from two or more video cameras taken at different angles.
- Watertight – Refers to mesh or surface data that does not contain any holes much
like a real object’s ability to hold water.
- White Light Scanning (Interferometry) –
Optical non-contact method for measuring physical parts. White light scanners obtain measurements of
an object by determining changes in the fringe and distortion of a pattern of white light projected on