A terrestrial laser scanner measures millions of points across the visible surfaces surrounding the instrument. These measurements are combined to create a detailed three-dimensional point cloud representing the shape, position and spatial relationship of buildings, structures and terrain.
The scanner is moved through or around the survey area so that the site is captured from multiple positions. The individual scans are then registered together, checked against survey control and processed into the drawings, models or point-cloud files required by the project team.
This guide explains how 3D laser scanning works, from survey planning and site capture through to registered point clouds, CAD survey drawings and three-dimensional models.
What Is 3D Laser Scanning?
3D laser scanning is a surveying method used to record the dimensions and visible geometry of an existing environment.
The scanner sends laser pulses towards surrounding surfaces and measures the distance between the instrument and the point where each pulse is reflected.
By measuring horizontal and vertical angles alongside each distance, the instrument calculates the three-dimensional position of each recorded point.
A single scan may capture a very large number of measured points. Together, these form a point cloud showing the visible surfaces surrounding the scanner.
The point cloud may include:
- Walls and floors
- Ceilings and roofs
- Doors and windows
- Columns and beams
- Stairs and changes in level
- Building services
- Plant and machinery
- External elevations
- Structures and terrain
The scanner records geometry rather than automatically identifying every object. Surveyors and CAD technicians interpret the point cloud when preparing the required drawings and models.
How Does 3D Laser Scanning Work on Site?
So, how does 3D laser scanning work during an actual survey? The exact workflow depends on the size and complexity of the building or site, the required outputs and the accuracy specification.
A typical 3D laser scanning survey involves the following stages.
1. Reviewing the Survey Brief
Before the site visit, the surveyor establishes what information the client requires and how the finished survey will be used.
The brief may confirm:
- The buildings or areas to be surveyed
- Whether internal and external areas are required
- The floors, roofs, elevations and structures to include
- The required drawing scale
- The required level of detail
- The coordinate system and level datum
- The required point-cloud format
- The required CAD or BIM outputs
- Site access and security arrangements
- The required delivery programme
A clear brief is important because scanning an entire building is not automatically the same as producing every possible drawing from the captured data.
2. Planning Scanner Positions
A terrestrial laser scanner works using line of sight. It can only measure surfaces that are visible from its current position.
The surveyor therefore plans a series of overlapping scanner locations throughout the building or site.
Scanner positions may be required:
- Inside each room
- Along corridors
- At staircases and landings
- At building entrances
- Around the external elevations
- Within roof spaces
- Inside plant rooms
- Around columns, machinery and other obstructions
Additional positions are often needed around complex geometry or where walls, furniture, vegetation or structures obscure the view.
3. Establishing Survey Control
Survey control provides a coordinated framework for the scanning work.
Control points may be established using a total station, GNSS equipment or another appropriate surveying method.
These points can be used to:
- Relate the scans to a site coordinate system
- Connect internal and external survey data
- Maintain consistency between different floors or buildings
- Check the registered point cloud
- Relate the survey to an agreed level datum
- Support future survey or setting-out work
Not every project needs to be connected to national coordinates, but the required system should be agreed before the survey begins.
4. Capturing Each Scan
At each position, the instrument rotates and measures the surrounding surfaces.
The scanner records distances and angles to produce a three-dimensional set of measured points. Many modern instruments can also capture photographic imagery so that colour information can be applied to the point cloud.
The scanning density and quality settings may be adjusted according to:
- The distance to the surfaces
- The required level of detail
- The complexity of the area
- The amount of movement on site
- The time available
- The intended output
A higher-density scan may capture finer detail but can take longer and generate a larger dataset.
5. Moving Through the Site
Once a scan has been completed, the instrument is moved to the next planned position.
Successive scans must overlap sufficiently so they can be connected during registration.
The surveyor continues through the building or site until the required areas have been captured. Field software may allow scans to be reviewed and registered while the survey is still in progress.
This helps the surveyor identify missing coverage before leaving the site.
6. Recording Supporting Observations
Laser scanning captures extensive geometric information, but additional observations may still be required.
The surveyor may also record:
- Room names and uses
- Construction materials
- Door and window descriptions
- Floor-level information
- Survey-control measurements
- Drainage or service details
- Features hidden from the scanner
- Photographs and site notes
These observations provide context that cannot always be derived reliably from the point cloud alone.
What Is a Point Cloud?
A point cloud is a collection of three-dimensional measured points.
Each point has a position defined by X, Y and Z coordinates. Depending on the equipment and processing method, the points may also contain colour or intensity information.
When viewed together, the points form a detailed representation of the scanned environment.
A point cloud is not the same as a finished CAD drawing or BIM model. It is the measured source dataset from which further outputs can be produced.
More information on point-cloud capture and survey services is available on our 3D laser scanning service page.
How Are Multiple Scans Joined Together?
The process of connecting individual scans into one coordinated dataset is known as registration.
Each scanner position initially has its own local coordinate system. Registration calculates how those individual scans relate to one another.
Cloud-to-Cloud Registration
Cloud-to-cloud registration compares overlapping surfaces within adjacent scans.
The processing software identifies matching geometry and calculates the best alignment between the datasets.
This method can be efficient where the scans contain sufficient overlap and varied geometry.
Target-Based Registration
Artificial targets may be positioned around the site and captured from more than one scanner location.
By identifying the same targets in multiple scans, the software can calculate the relationship between them.
Survey-Control Registration
Scans may also be connected or checked using coordinated survey-control points.
This can be particularly important where:
- The building is large or complex
- Internal and external datasets must be linked
- Several survey teams or instruments are involved
- The point cloud must relate to an existing site grid
- The project requires independent checks
Registration Checks
Registration software may report how closely overlapping scans agree, but a low registration error does not by itself prove that the full survey is accurate.
The completed point cloud should also be reviewed against the project control, known dimensions and independent check measurements where appropriate.
How Is the Point Cloud Processed?
After registration, the point cloud is reviewed and prepared for its intended use.
Processing may include:
- Removing unwanted points
- Checking registration
- Applying coordinates and levels
- Combining internal and external scans
- Dividing the data by floor, building or area
- Creating clipping regions
- Applying photographic colour
- Exporting agreed file formats
- Preparing data for CAD or BIM software
The amount of processing required depends on the project and the software being used by the client.
How Are Survey Drawings Produced from a Point Cloud?
Once the point cloud has been registered and checked, it can be used as measured source information for CAD drawings.
The technician views sections or slices through the point cloud and traces the relevant building features.
Floor Plans
A horizontal slice through the point cloud can be used to draw walls, doors, windows, stairs, columns and other plan features.
Further interpretation is normally required where features are hidden, obscured or positioned above or below the selected cutting plane.
External Elevations
The point cloud can be viewed orthographically from each side of the building.
The technician may then draw:
- External walls
- Doors and windows
- Roof lines
- Ridges and eaves
- Rainwater goods
- Architectural features
- Visible materials
- Changes in level
Internal Elevations
Internal elevations may be produced where the project requires detailed information about walls, openings, fitted features or architectural details.
Building Sections
Vertical slices through the registered point cloud can be used to prepare building sections.
Sections may show:
- Floor levels
- Ceiling levels
- Roof structure
- Staircases
- Changes in level
- Structural elements
- The relationship between floors
Roof Plans
External scanning can help record roof geometry, including ridges, hips, valleys, parapets, rooflights and changes in roof level.
Some roof areas may remain hidden from ground-based scanner positions and may require elevated access, aerial data or additional observations.
Further information about drawing production is available on our measured building surveys page.
What Other Outputs Can Be Produced?
The point cloud can support several survey and design outputs in addition to traditional two-dimensional drawings.
Registered Point-Cloud Files
The registered point cloud may be supplied in agreed industry formats for use in point-cloud viewing, CAD, engineering or modelling software.
The required format should be confirmed before processing because software compatibility varies.
Three-Dimensional CAD Models
Selected structures, surfaces or building elements can be modelled in three dimensions using the point cloud as measured reference data.
Building Information Models
A BIM model may be created from the point cloud where the project requires intelligent modelled building elements.
The required level of information and modelling tolerance should be agreed clearly before work begins.
A point cloud does not automatically become a BIM model. Producing the model involves interpretation, modelling decisions and additional office work.
Mesh and Surface Models
Point-cloud data may be processed into surface meshes for selected visualisation, analysis or engineering applications.
Deviation and Comparison Analysis
Point clouds can be compared with design models or previous surveys to identify differences between existing, proposed or changing conditions.
Where Is 3D Laser Scanning Used?
Measured Building Surveys
Laser scanning is widely used to record existing buildings for refurbishment, alteration, planning and design work.
It is particularly useful where the building has irregular geometry, multiple levels or complex architectural features.
Historic and Listed Buildings
Point clouds can provide a detailed measured record of historic structures and architectural features.
Historic England publishes specialist guidance on 3D laser scanning for heritage, including its use in architecture and archaeology.
Industrial and Plant Environments
Laser scanning can capture machinery, pipework, steelwork and complex industrial installations.
The data may support modification, coordination, clearance checking and as-built recording.
Construction and As-Built Surveys
Scanning can provide a dated record of completed work and allow existing conditions to be compared with design information.
Structural and Engineering Surveys
Engineers may use point-cloud data to understand the geometry of bridges, retaining walls, structural frames and other assets.
Complex or Inaccessible Areas
Laser scanning can reduce the amount of direct physical measurement required in awkward or hazardous areas.
It does not remove the need for safe access planning, and hidden surfaces still cannot be recorded without an adequate line of sight.
What Are the Benefits of 3D Laser Scanning?
Dense Survey Information
The scanner records a dense set of measurements across visible surfaces rather than a limited selection of individually observed points.
Efficient Site Capture
Large quantities of spatial information can be recorded during the site visit, reducing the need to revisit every feature individually.
Detailed Three-Dimensional Record
The point cloud preserves the spatial relationship between the recorded features and provides a useful reference after the site work has been completed.
Support for Multiple Outputs
The same registered dataset may support floor plans, elevations, sections, models and other agreed outputs.
Reduced Return Visits
A comprehensive point cloud can allow additional dimensions and views to be examined later, although only where the required surfaces were captured clearly during the original survey.
What Are the Limitations of 3D Laser Scanning?
Line of Sight
The scanner cannot measure through solid objects.
Areas hidden behind furniture, machinery, vegetation, parked vehicles, walls or other obstructions will not be captured from that scanner position.
Reflective and Transparent Surfaces
Glass, mirrors, highly reflective finishes and some dark or wet surfaces can produce incomplete, distorted or noisy measurements.
Movement
People, vehicles, machinery and vegetation moving during a scan may create unwanted or duplicated points.
Large Data Volumes
Point-cloud files can be large and may require appropriate hardware, storage and specialist software.
Interpretation Is Still Required
A scanner records measured points but does not automatically understand what each point represents.
Surveyors and technicians must still interpret the data and apply the required drawing conventions.
It Does Not Replace Every Survey Method
Total stations, GNSS equipment, tape measurements and other survey methods may still be required for:
- Survey control
- Independent checks
- Hidden features
- Feature identification
- Drainage information
- Boundary detail
- Areas where scanning is unsuitable
How Accurate Is 3D Laser Scanning?
There is no single accuracy figure that applies to every project.
The finished survey depends on:
- The scanner used
- The distance from the scanner to the surface
- The angle of incidence
- The scanning resolution
- The registration method
- The survey-control arrangement
- Site conditions
- Surface materials
- The required drawing scale
- Processing and quality checks
The required accuracy and level of detail should be agreed before the survey is planned.
How Does 3D Laser Scanning Work Compared with Traditional Surveying?
Traditional surveying commonly records selected points individually using a total station, GNSS receiver or direct measurement.
Laser scanning records dense surface information across everything visible from the instrument position.
Neither method is automatically better in every situation.
A total station may be more efficient where only a small number of precise points are required. Laser scanning may be more efficient where the project needs comprehensive geometry across a complex environment.
Many measured surveys combine both approaches: laser scanning provides dense spatial information, while conventional survey observations provide control, checks and targeted detail.
How Much Does 3D Laser Scanning Cost?
The cost depends on the size, complexity and required outputs of the project.
Factors affecting the fee may include:
- The number and size of buildings
- The number of floors and rooms
- Internal and external access
- The complexity of the geometry
- Site occupancy and working restrictions
- The number of scanner positions
- The survey-control requirements
- The required point-cloud format
- The number and type of drawings
- The required level of detail
- Whether a CAD or BIM model is required
- The required delivery programme
The scanning is only one part of the total work. Registration, checking, point-cloud processing, drawing and modelling can represent a substantial part of the project.
What Information Is Needed for a Quotation?
To prepare an accurate quotation, it is helpful to provide:
- The site address
- Plans or photographs of the property
- The buildings and areas to be surveyed
- The number of floors
- Whether roof spaces or external areas are required
- The required drawings or models
- The required point-cloud formats
- The required coordinate system and datum
- Known access or safety restrictions
- The required completion date
A clear scope prevents misunderstandings about what will be captured and which deliverables are included.
Frequently Asked Questions
How does 3D laser scanning work in simple terms?
A laser scanner measures distances and angles to visible surfaces from multiple positions. The scans are then joined together to create a coordinated three-dimensional point cloud that can be used to produce survey drawings, models and other measured outputs.
Does a laser scanner create finished drawings automatically?
No. The scanner creates point-cloud data. CAD drawings and BIM models require additional processing and interpretation.
Can 3D laser scanning measure through walls?
No. It records visible surfaces reached by the laser. It cannot see through solid walls, floors or roofs.
Can it scan an occupied building?
Yes, but people, furniture, access restrictions and movement may affect coverage and scanning efficiency.
Can point clouds be supplied directly to the client?
Yes. The required file format and software compatibility should be agreed before the data is exported.
Can additional drawings be produced later?
Potentially, provided the original survey captured the required surfaces and level of detail. New site work may be needed if the relevant areas were obscured or excluded.
Is 3D laser scanning suitable for small buildings?
It can be, particularly where the building is complex or several drawings are needed. For a very small and simple requirement, another survey method may be more efficient.
3D Laser Scanning from Pinpoint Mapping
Pinpoint Mapping provides terrestrial 3D laser scanning for measured building, land, heritage, industrial and construction projects across Bristol, Bath, the South West and other parts of the UK.
Depending on the project brief, outputs may include:
- Registered point-cloud data
- Floor plans
- External elevations
- Internal elevations
- Building sections
- Roof plans
- Three-dimensional CAD data
- BIM models
- PDF survey drawings
- Additional outputs by agreement
Each project is assessed individually so that the scanning method, survey control, accuracy and deliverables are appropriate for the intended use.
Request a 3D Laser Scanning Quotation
To request a quotation, send us the site location, the areas to be surveyed, the required outputs and any available plans, photographs or project specification.
Contact Pinpoint Mapping by telephone or email, or use the Request a Quote form on our website. We will review the information and provide a quotation based on the required survey scope.