3D Scanning Terms
This glossary of 3D laser scanning terms provides general information about words and terms associated with 3D laser scanning.
2D Drawings or 2D CAD Drawings – a 2D representation of a CAD model.
3D Laser Scanning – a technology that employs lasers to measure an object's geometry to craft a digital 3D model. This technology is used throughout a number of industries and settings, as 3D laser scanning can capture three-dimensional data of objects, regardless of their surface features or size.
3D Laser Scanner – 3D laser scanners are an instrument which uses LiDAR (light detection and ranging) to measure and record precise locations and distances, ultimately producing a point cloud file. The technology enables users to produce highly accurate digital measurements and images quickly and easily.
3D Scanning – the process of analyzing a real-world object or environment to collect existing conditions data. The collected data can then be used to construct digital 3D data.
3D Models or 3D BIM Models – 3D models are accurate digital representations of a building or site to facilitate design, construction and operational processes. 3D models provide users with the ability to break down architectural, structural and MEP building features and see how they fit into a single finalized structure. Users can isolate and alter walls, columns, windows, doors, etc. to support the planning and design needs of any project.
Accuracy – how close a measurement is to its true value.
Airborne Laser Scanning – a measurement system in which pulses of light (most commonly produced by a laser) are emitted from an instrument mounted in an aircraft or drone and directed to the ground in a scanning pattern.
Alignment – the process of aligning two objects in a common coordinate system. Commonly refers to aligning scan data to known coordinates or reference objects in construction and engineering applications.
As-Built – an object’s real-world condition and appearance.
AutoCAD – Autodesk's CAD software that can be used to create precise 2D and 3D drawings and models, as well as electrical diagrams, construction drawings, and much more. AutoCAD has become a generic term and is considered the industry standard.
AutoCAD Civil 3D – a civil engineering design and documentation software that supports Building Information Modeling (BIM) workflows inside AutoCAD.
BIM – Building information modeling (BIM) is an intelligent software modeling process that engineers, contractors, and architects can use to collaborate on a building’s design, construction, and operation. It’s more than just a model. It’s a process of collecting and managing data throughout a building’s entire life cycle.
Computer Aided Design or CAD – the use of computer-based software to aid in design processes. CAD software is frequently used by engineers and designers. CAD software can be used to create 2D drawings or 3D models.
Colorized Point Cloud – the colorized point cloud contains the RGB value of the raster pixel that has the same location.
Colorized Triangulated Mesh – a mesh is a visualization of point cloud data that basically connects the dots to form triangles. In a colorized triangulated mesh, RGB colors from photos are applied to the points to colorize the mesh.
Datum – any level surface, line, or point used as a reference. A basis for horizontal control surveys, consisting of the longitude and latitude of a certain point.
Decimation – decimation refers to reducing the number of samples in a population. In 3D scanning, decimation usually refers to lowering the number of points reported from the scanner on a surface without distorting the detail or color. Decimation is used when there are a large number of unnecessary overlapping points or surface mesh triangles.
Degrees of Freedom – describes the number 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).
Design-Intent – the schematic representation of something, the structure as it was originally designed in a CAD environment. Design-intent deliverables will be shown as a "best fit" to the point cloud working within customary standards, such as walls being modeled 90 degrees perpendicular to floor, pipes and conduit modeled straight, floors and ceilings modeled horizontal, and steel members modeled straight. This will produce cleaner 2D drawings and will allow for easier dimensioning of the scan area. The deliverables will not exactly follow the scan data to maintain design-intent standards. The majority of users will want this option for their deliverables.
Deviation – deviation refers to the difference in the size and shape of an as-built environment versus its design specifications.
Digital Twin – a digital twin is a virtual model that accurately represents an existing physical space. It digitally represents a building’s architecture, structure and systems. The most useful purpose of digital twin technology occurs during the construction design and planning process. A digital twin can be used to plan for building improvements, improve efficiencies and optimize workflows, which can then be applied back to the actual physical asset. In a digital twin environment, ideas can be tested with few limitations.
Digital Archiving – storing data digitally. Objects can be scanned and processed for digital archiving purposes.
File Format – data published in a type of file compatible with end use. Such as .DWG, .DGN, .E57, .RCP, .RVT, .LGS, .STP, .IGES, .IFC, .OBJ, .STL, etc.
Fillet – a surface that connects two or more faces. This surface is usually an arc.
Intensity Level Black and White Laser Scan – The default for construction-grade 3D laser scanning is intensity, black and white, or greyscale. This refers to the coloring of the point cloud inside of software such as Revit, Recap, and TruViews. Data can be viewed in RGB, intensity, black and white or greyscale. The scanner does not need light to capture information in greyscale, black or white, or intensity, but color scans do require adequate lighting.
Laser Based 3D Scanners – use a process called trigonometric triangulation to accurately capture a 3D shape as millions of points. Laser scanners work by projecting a laser line or multiple lines onto an object and then capturing its reflection with a single sensor or multiple sensors. The sensors are located at a known distance from the laser's source. Accurate point measurements can then be made by calculating the reflection angle of the laser light.
Laser Pulse-Based 3D Scanners – laser pulse-based scanners, also known as time-of-flight scanners, are based on a very simple concept: the speed of light is known very precisely. Thus, if the length of time a laser takes to reach an object and reflect back to a sensor is known, the distance from sensor to object is known. These systems use circuitry that is accurate to picoseconds to measure the time it takes for millions of pulses of the laser to return to the sensor, and calculates a distance. By rotating the laser and sensor (usually via a mirror), the scanner can scan up to a full 360 degrees around itself.
Laser Phase-Shift 3D Scanners – laser phase-shift systems are another type of time-of-flight 3D scanner technology, and conceptually work similarly to pulse-based systems. In addition to pulsing the laser, these systems also modulate the power of the laser beam, and the scanner compares the phase of the laser sent out and returned to the sensor. Phase shift measurement are typically more accurate and quieter but are not as flexible for long range scanning as pulse-based 3D scanners. Laser pulse-based 3D scanners can scan objects up to 1000m away while phase shift scanners are better suited for scanning objects up to 300m or less.
LiDAR - Light Detection and Ranging – is a remote sensing method that uses light in the form of a pulsed laser to measure ranges (variable distances) to the earth. These light pulses—combined with other data recorded by the scanning system — generate precise, three-dimensional information about a site and its surface characteristics.
Merge – combining two or more scan data sets into one larger data set.
Mesh – a mesh is a visualization of point cloud data that basically connects the dots to form triangles. A 3D mesh can be created from a point cloud in .fbx, .stl, .obj, and .ply file formats. Meshes are volumetrically accurate, high density and high resolution. Meshes allow users to view the object’s geometry inside a CAD environment without having to navigate a point cloud. Meshes can be used for representing scanned elements with fine, organic details such as monuments and statues that are otherwise difficult to reproduce in CAD.
Mobile Mapping or Mobile Laser Scanning – is a technology on a mobile system for generating highly accurate 3D point clouds and has many potential applications.
Noise – The “fuzziness” of the point cloud. Noisy points show up in every raw data set, regardless of the scanner, because the physical behavior of the laser sensor creates random imperfections in the data.
Photogrammetry – is a three-dimensional coordinate measuring technique that uses photographs as the fundamental medium for metrology or measurement.
Precision – the repeatability of performing a measurement.
Point Cloud – a point cloud is a collection of individual data points in a three-dimensional plane with each point having a set coordinate on the X, Y, and Z axis. The point cloud is the output of the 3D laser scanning process. Point clouds are typically represented by .ptg or .e57 point cloud files and Autodesk Recap files in .rcs and .rcp format. This is also referred to as the raw scan data from the laser scanner.
Quality Inspection – the process of evaluating a building or site and comparing it to the design specifications that are described in the project’s CAD file. Inspection is an “as-built” vs “as-designed” comparison.
Registration – registration is the process of compiling or “tying together” individual laser scans into a cohesive point cloud.
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, users 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 less the detail.
Revit – a building information modeling (BIM) software by the company Autodesk. It’s generally used by architects, structural engineers, mechanical, electrical, and plumbing (MEP) engineers, designers, and contractors to view point clouds and foster collaboration. Autodesk Revit allows users to create, edit, and review 3D models in exceptional detail, including the point cloud. Part of the Autodesk Suite, it is easily interchanged with AutoCAD, Navisworks, and other Autodesk Suite software. It can also export IFC file formats for use in other programs.
ReCap – is an easy-to-use program that works with native point cloud files created with laser scans. The “ReCap” part of the name is short for “reality capture”, and the system is included in the Autodesk Design Suite. ReCap is the gateway from point clouds to all of Autodesk’s software.
Scan – measuring the site, capturing data, and transferring the measured points to the computer. It also refers to the computer file that is based on the physical object, i.e., the xyz coordinates that represent physical measurements taken by the laser scanner.
Scan to BIM – scan-to-BIM is the process of digitally capturing a site with a 3D laser scanner and using the data to create a BIM model.
Short Range 3D Scanners – short Range 3D scanners typically utilize a Laser triangulation or Structured Light technology.
SLAM – stands for Simultaneous Localization and Mapping. SLAM's purpose is to move through a given space to create a digital map of that space that users can refer to.
Solids – solids can be used to graphically represent the mass of a subassembly shape and can be used to extract mass properties, such as volume.
Targets – targets are physical objects that laser scan technicians set up on site that scanning software uses to tie together multiple scans. Also known as 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.
Terrestrial Laser Scanning – (TLS), also referred to as terrestrial LiDAR (light detection and ranging) or topographic LiDAR, acquires XYZ coordinates of numerous points by emitting laser pulses toward these points and measuring the distance from the device to the target.
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.
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. See also Mesh and Colorized Triangulated Mesh.
Uncertainty – what is the highest probable absolute difference between the measured value and the true value.
3D View – there are options to select predefined standard orthographic and isometric 3D views in AutoCAD by name or description.
Base View – the first view created in a drawing. The base view is the source for subsequent views and controls scale and alignment.
Detail View – an enlarged view of a specified portion of another drawing view. By default, the scale of the detail view is double the scale of the parent view, but users can specify any scale. A detail view is created without alignment to its parent view.
Elevation View – an elevation drawing is the view that users would see in real life if they stood on the floor or ground and looked at the wall. This view can be either an exterior or interior view.
Floor Plan – a base view attributed to a level of a floor of a building or site. A floor plan is a view of a building drawn as if users were looking at it from the ceiling.
Orthographic View – orthographic drawings display two-dimensional views of structure, piping, valves, equipment, etc. in 3D models.
Perspective View – perspective view is a two-dimensional representation of a three-dimensional space, where the apparent size of an object decreases as its distance from the viewer increases.
Projected View – an orthographic or isometric view that is generated from a base view or other existing view. Users can create multiple projected views in a single operation.
Section View – a view created by sketching a line that defines a plane used to cut through part of a building. Users draw the cutting line when users create the view, or select it from a sketch associated to the parent view. The cutting line can be a single straight segment or multiple segments. The cutting line arrowheads on the base view automatically orient to reflect the position of the section view relative to the base view.
Site Plan – a site plan, sometimes referred to as a plot plan or a site map, is a drawing that depicts the existing conditions of a given area. The site plan shows the layout of a property or site, including the location of buildings, structures and site details.
Watertight – refers to mesh or surface data that does not contain any holes much like a real object’s ability to hold water.