3D Metrology terminology


3D Scanning – The process of collecting 3D data of a physical object or structure through means of Structured light, Laser or LiDAR  systems.

3D CAD - 3 dimensional Computer Aided Design

3D to CAD - Converting 3D point cloud data or polygonal models to a standard feature based model

3D Digitizer - An input system that records x, y and z coordinates of a real object


Accuracy - The degree of how close a measurement is to the recognized true value

Alignment - Refers to the method of aligning scan data or CAD data to one another. Usually done using 'best-fit', feature alignments or Datum alignments

As-built - Details existing real world conditions of a building, structure or environment


BIM (Building Information Modeling)


CAD - Computer-aided design (CAD) is a type of 3D model used to aid in the creation, modification, analysis, or optimization of a design.
CAM - Computer-aided manufacturing (CAM) refers to the use of a CAD model and CNC equipment to create tool paths for the purpose of manufacturing

CNC - Computer Numerical Control (CNC) is an automated machining process used for the purpose of machining operations

Calibration - Is the comparison of measurement values from a device against a calibration standard of known accuracy.

Computational Fluid Dynamics (CFD) - The produce of quantitative predictions of fluid-flow in a system or component

CMM - Coordinate Measuring Machine (CMM) is a device that measures the geometry of a physical objects by means of contact probing

CT Scanning - Computed Tomography (CT) scanning is a X-ray scanning process, that uses X-rays to generate 3D model of internal and external features.


Datum - Is a reference point, surface, and axis or three planes on an object which measurements are made

Datum Feature - Is a physical Datum that all other dimensions referenced to it need to be in specification.

Dimensional Metrology - The science of calibrating and using physical measurement equipment to quantify the physical size of or distance from any given object

Drone - Unmanned aircraft or ship that can navigate autonomously, without human control or beyond line of sight:


Exact Surfacing - The process of creating a computer generated model that is true one-to-one representation of the existing part


Finite element analysis (FEA) - Finite Element Analysis (FEA) is the process of simulating the behavior of a part or assembly under given conditions so that it can be assessed using the finite element method (FEM)

First Article Inspection (FAI) - A First Article Inspection (FAI) is a design verification and design history file and a formal method of providing a reported measurement for each manufactured feature of a part or assembly

Free-Form Shapes - also called organic shapes, are irregular and uneven


Gage R&R - Gage Repeatability & Reproducibility, is a statistical tool that measures the amount of variation in the measurement system

GD&T - Geometric Dimensioning and Tolerancing is a system that uses symbolic language to define and communicate engineering tolerances






Laser Scanning - A method of using controlled Laser beams either visible or invisible to measure and capture environments in 3D space with speed and accuracy. A laser line is projected onto a surface and the deformation is recorded and measured by a sensor to calculate the angle of deviation. Knowing how far the scanner is from the surface and the angle of deviation the scanning hardware and software are able to map the surface and record a 3D scan

Laser Tracker -  An instrument that accurately measure objects by determining the positions of an optical target held against the object being measured

Long Range Scanning - Also known as LiDAR scanning is based on the time of flight of a laser beam. A surface is illuminated with a laser and a sensor calculates how long it took for the laser to return. These scanners measure the time interval between emitted laser to hit an object, get reflected and come back


Maximum Permissible Error - Is the extreme value of allowable measurement error, for a given measurement, measuring instrument, or measuring system.

Measurement - The process of associating numbers with physical quantities and phenomena. Measurement is fundamental to the sciences, engineering, construction, and other technical fields

Measuring System - is a collection of units of measurement and rules relating them to each other.

Mesh - Also known as a polygon mesh, is a collection of vertices, edges and faces that defines the shape of an object or surface

Metrology - The study of measurement

Micron (µm) - unit of length equal to one millionth of a meter, used in many technological and scientific fields

Modeling - is the process of developing a digital mathematical representation of any surface of an object in three dimensions


Noise - Is typically additional or misrepresented measurement data when 3D scanning.

Nominal Dimensions - Refers to the idealized or originally designed figures outlined by a 3D CAD model or print drawing

Non-Contact Measurement - The ability to capture and record a surface or object using an optical device for the purpose of analysis

Non-Parametric Model - Statistical models that rely upon continuous data, rather than discrete values.

NURBS - Non-Uniform Rational Basis Spline (NURBS) is a mathematical model using basis splines to generate curves and surfaces and create a true representation of an existing part


Ordered Data - Also Known as ordinal data, are types of data in which the values follow a natural order or sequence

Outlier - is a data point that differs significantly from the rest. An outlier may be caused by variability or error in the measurement process


Parametric Model - Is a 3D CAD model created using geometric primitives and constraints, this type of model is fully defined

Parametric Modeling - Refers to the process of generating CAD using geometric primitives and constraints to fully define a model and capture the design intent. This form of modeling usually generates a features tree which allows the user to modify and make repetitive changes to a family of parts

Phase Based Scanners -Utilize a constant beam of laser energy that is emitted from the scanner. The scanner then measures the phase shift of the returning laser energy to calculate distances.

Photogrammetry - Is the process of making precise measurements of three-dimensional objects and terrain features from two-dimensional photographs. There exists aerial and terrestrial versions of this form of scanning

Point Cloud - A set of data points in space. The points represent a 3D shape or object. Each point has a set of X, Y and Z coordinates.

Polygonal Model - Computer generated model typically created from an existing point cloud that has been polygonized by defining three-dimensional points and the lines that connect them to create a straight sided polygon of three sides or more

Portable CMM - is a device for collecting measurements off the surface geometry of an object. When contact with the surface is made one measurement point is recorded with an X, Y and Z coordinate

Precision - Refers to the closeness of two or more measurements to each other. Precision is independent of accuracy. You can be very precise but inaccurate and vice versa

Probe - A physical measurement instrument attached to a device to capture and record points of an object or surface


Quality Inspection - The process of analyzing manufactured parts or components in a 3D environment. Typically parts are 3D scanned and the data is the overlayed to the original CAD data in order to generate colour map inspection reports and verify GD&T callouts


Raw point data - Sometimes called source data is data that has not been processed for use. An example of this is point cloud data

Repeatability - Defined as the variation in output data over time from a stationary or fixed target. Differences measured by the scanner are compared to determine sensor accuracy.

Repeatability Condition - Independent test results which are obtained with the same method, items, conditions and operator to reflect the best achievable precision.

Reproducibility - The measure of how consistently reliable results are achieved during scanning or testing

Resolution - The smallest distance between two points on a laser line.

Reverse Engineering - Recreating CAD data of a product or manufactured part from scan data


Scan Density - Coincides with resolution but often refers to the data density captured during scanning of a particular region.

Scan Speed - Specified in points per second, it refers to how many points and how fast the scanner is able to emit and track during the scanning process

Scan to CAD - The process of using scan data to generate a parametric or NURBS model

Scan to print - The process of using scan data which has been polygonized for the purpose of 3D printing

Sectioning - Simulates cutting away material from the model so you can see internal features. This is useful when you need to create sectioned views of a part or assembly for presentation or documentation purposes, but you do not want to physically modify the parts.

Short range scanning - usually defined as a scanner that performs best within one meter

Solid Modeling - Is the creation of a 3D CAD model that is geometrically correct to the design parameters

SPC - Statistical Process Control (SPC) usually organized into charts, analyze the performance of a manufacturing process by plotting data points, control limits, and a center line to assess the processes capability.

Structured Light - Much like the laser line method the angle of deviation is measured and calculated to map the surface and record a 3D scan. The main difference is that instead of using a laser line, a series of linear patterns are projected onto the surface and the deviation is measured by examining the edges of each light pattern

Surface Model - is the method of modeling true representations of an existing surface to capture and show the current conditions, validate imperfections or to build onto the existing surface. This is typically achieved through NURBS surfacing

Surface Profile - In respect to GD&T, describes a 3-Dimensional tolerance zone around a surface

Survey Control - Is a point on the ground or any permanent structure whose horizontal and vertical location and position is known. Control points are used as a starting point of all types of surveys.


Temperature Compensation - Reduces the effect of temperature fluctuations on components in the scanner

Time of Flight Scanners - Measures the time it takes to emit a laser towards a target and return to the sensor which then measures and compares the sending and arrival time to create points in space with X, Y and Z values

Tooling Ball - A precision ground and threaded sphere typically affixed to a fixture to locate a point. 2 points create a line, 3 points create a plane which can the be used to align and orient your scans

Traceability - In respect to 3D scanning and modeling, refers to the workflow taken from start to finish as each step builds upon the previous



Verification - Process of confirming the accuracy and reliability of scan data and the various data sets to one another

Validation - To check or prove the accuracy of the scan data captured

Volume Measuring - The amount of space, measured in cubic units, that an object or substance occupies

Volumetric - Relates to the measurement of volume


Water tight models - Is a Polygonal model or mesh that is fully defined with every triangle edge in the model having exactly two neighbors. This implies there are no hole or overlapping edges in the model, typically used for the purpose of quantitative measurements or 3D printing

White Light Scanner - is a type of Structured Light scanner using white light