Need for Accurate Information in Construction

Throughout the history of construction, designers and builders had to rely on outdated drawings, manual measurements with tapes, and other old-fashioned ways of capturing site information. All these sources of uncertainty caused errors, lack of coordination, and rework.

It is known that rework makes up from 4% to 9% of the total cost of the project. Less than 1% of major construction projects are completed on time and under budget. Construction needs better data.

3D laser scanning is a modern reality capture technology that provides an exact recording of existing buildings, structures, and construction sites as highly detailed three-dimensional data.

An exact description of conditions leads to:

  • Fewer design errors: Decisions are based on reality.
  • Reduction of rework and change orders: Issues are addressed virtually before construction starts.
  • Improvement of coordination: Teams work on the single source of truth.
  • Safer surveying: Data is collected remotely, protecting people from danger.

This article will define 3D laser scanning, explain the process of laser scanning, explore construction applications, discuss the advantages and disadvantages of the technology, and show the relation of 3D laser scanning to as-built BIM.

What Is 3D Laser Scanning?

In short, 3D laser scanning is a technique of non-contact measuring of distances from a scanner to the surfaces around it. It sends out laser pulses and measures the time it takes to come back to calculate distances with high precision. Millions of individual measurements create three-dimensional data that describes the scanned environment.

LiDAR (Light Detection and Ranging) is the core technology that makes 3D laser scanning possible. The technology is based on the same principle—it sends out light pulses and measures the time it takes to come back to determine the distance.

The technology is a type of reality capture—a process of acquiring precise digital information about the physical environment. It can capture walls, floors, ceilings, structural elements, MEP systems, terrain, and architectural details.

A point cloud is the result of laser scanning—it is a set of individual points that represents the three-dimensional geometry of the scanned space. Points contain spatial information, usually described with X, Y, and Z coordinates.

Depending on the requirements of the project, the deliverable can be:

  • Point-cloud files
  • Colored and photographic point clouds
  • 3D mesh
  • Floor plans, elevations, sections, and profiles
  • CAD and BIM models

According to Autodesk, 3D laser scanning is a technique of rapid measurement of distances to surfaces and creation of detailed three-dimensional data about buildings, objects, and landscapes.

How Does 3D Laser Scanning Work?

It is a step-by-step process of transforming physical spaces into usable digital information.

Step 1: Plan the Scan

Each good scan starts with an idea. The teams should figure out:

The purpose of the scan: existing condition documentation, renovation planning, construction progress tracking, quality control, or scan-to-BIM development.

Required accuracy: the level of precision needed for the particular purpose.

Coverage: the extent of the area to be captured.

Type of deliverable: point clouds, drawings, models, or BIM files. Software and file formats that will be used downstream.

According to the above-mentioned parameters, teams choose the right scanner and the locations of the scanning stations.

Step 2: Set Up the Scanner

The scanner is mounted on the tripod or some movable equipment. Surveying control points and reference targets are installed when required to ensure proper alignment. The project coordinate system, coverage, and possible obstacles for scanning are checked.

Step 3: Capture the Site

The scanner makes turns and sends laser beams to the surrounding area. Laser pulses are reflected from visible surfaces and come back to the scanner, which calculates distance using time-of-flight or phase-shift measurements. Angular and distance measurements are combined to place a point in three-dimensional space.

Modern terrestrial laser scanners can measure up to 2 million points per second, decreasing time spent on capturing on-site significantly. Usually, multiple scanning positions are required to capture areas that are hidden from a single viewpoint.

Photographs can be taken during scanning to enrich the point cloud with color and texture information.

Step 4: Register and Clean the Scans

To unite individual scans in one coordinated dataset, the process of registration is performed. It is done using targets, control points, or cloud-to-cloud methods.

After that, cleaning of the data is necessary to get rid of noise, redundant points, moving objects (for example, people or equipment), and any unnecessary information. The point cloud is georeferenced so that it matches the survey, GIS, or BIM coordinates.

Step 5: Create Deliverable from the Point Cloud

Specialized point-cloud processing software allows inspection and organization of the data. With this data, the team can produce:

  • 2D drawings (floor plans, elevations, sections)
  • CAD files
  • 3D mesh
  • As-built BIM models
  • Digital twin

The deliverable is chosen according to the customer’s requirements and the further purposes of the scan.

What Is As-built BIM?

As-built BIM is a Building Information Model of a building as it was built or exists now, instead of how it was designed. As it is, in reality.

Scan-to-BIM is the process of converting a point cloud into an intelligent BIM model:

  • Existing conditions are captured using 3D laser scanning.
  • Scans are registered and processed.
  • The data is imported into BIM software (for example, Autodesk Revit).
  • Walls, slabs, columns, roofs, equipment, and MEP systems are modeled on the basis of the data from the point cloud.
  • Comparison of the BIM model with design documents or construction progress is made.
  • As-built BIM allows teams to:
  • Design additions and renovations accurately.
  • Coordinate new systems with existing conditions.
  • Perform clash detection between the proposed design and the existing building.
  • Help facility management and maintenance.
  • Make sure the information about the building is preserved.

It is known that the integration of BIM with 3D laser scanning solves issues like rework of the building, increases project completion time, reduces project costs, and improves communication, cooperation, and collaboration.

According to Autodesk, the point cloud data can be integrated into BIM software to create a model of the existing conditions and detect clashes between the proposed design and the actual building.

Applications of Laser Scanning in Construction

There is a variety of construction applications of 3D laser scanning, and each of them adds value to the project:

  • Surveying of existing conditions: documenting buildings, interiors, facades, industrial facilities, and infrastructure prior to the design phase.
  • Documentation of renovation and retrofit projects: documenting older or inadequately documented buildings to minimize uncertainty and surprises during construction.
  • Scan-to-BIM: creating the BIM model from physical site data.
  • Clash detection: comparing the scan data with architectural, structural, and MEP designs to find out the conflicts and solve them before construction.
  • Quality control of construction: verifying that installed elements comply with drawings and specifications.
  • Tracking the progress of construction: comparing scans with different dates to track the progress of the construction, verify completion, and solve scheduling conflicts.
  • Documenting as-built conditions: creating a reliable record of the project upon its completion for owners and facility management.
  • Checking of prefabrication: confirming dimensions and site conditions to manufacture the elements outside and ensure their perfect fit.
  • Safety and clearance checks: checking overhead clearances, access routes, barriers, and hazardous areas without making any measurements manually.
  • Historic preservation: documenting delicate architectural details without physical contact.
  • Facility management: making a digital reference for maintenance, repairs, additions, and future renovations.

Research has shown that the implementation of scan-to-BIM for progress cost reporting decreases the time of reporting by 18%, and estimation accuracy is increased by 12%.

Advantages of 3D Laser Scanning

There are numerous advantages associated with 3D laser scanning in construction:

  • Precision and detail: 3D scans provide more complete and detailed information about geometries and existing conditions compared to individual manual measurements. Under favorable conditions, professional scanners may achieve millimeter-level accuracy.
  • Speed of surveying: Areas may be scanned, which allows for fewer repeated site visits and helps to speed up the project.
  • Less risk of rework: Discrepancies and design conflicts can be detected at early project stages when their correction is significantly cheaper.
  • Enhanced safety: Operators can collect data from a safe distance in difficult-to-reach and dangerous locations.
  • Greater collaboration: Stakeholders work based on a common digital representation of the site, which reduces misunderstanding.
  • Improved project visualization: Point clouds, models, and digital twins allow for better understanding of complex spaces by all stakeholders involved in the project.
  • Documenting as-built conditions: Owners receive valuable documentation for further operation and construction works.
  • Cost and schedule advantages: Improved information leads to fewer delays, material waste, and corrections required later on.

Matterport notes accuracy, shortened survey time, improved safety of data collection, clash detection, and documenting renovation as the major advantages of 3D laser scanning in construction.

Limitations and Implementation Factors

Although extremely useful, 3D laser scanning is not a panacea. Before applying the technology, companies should consider its limitations:

Initial expenses: Buying equipment, installing necessary software, training operators, maintaining scanners, and storing large amounts of data may be quite costly.

Specialized knowledge: Operators need to know the process of scanning, its registration, accuracy, coordinate systems, and how it relates to BIM.

Data size: Large amounts of data in the form of point clouds may be difficult to store, transfer, process, and share. Processing is time-consuming and, if not properly done, may cause errors in modeling.

Line of sight limitations: Scanning lasers are unable to capture the geometry located behind walls, objects, equipment, or other obstacles.

Environmental factors: Reflective, transparent, dusty, wet, or any other problematic surfaces may influence the scan quality. Material stockpiling and active construction works may impede the collection of scan data.

Software: Check necessary file format requirements before scanning and delivering data.

Planning: Determine the aim, accuracy, control points, scanning locations, and desired results in advance.

Implementation: Companies may buy the equipment, lease scanners, or hire specialized scanning services. There is no universal optimal device, as the combination of accuracy, efficiency, cost, and operator expertise has to be taken into account when choosing the equipment.

Future of Reality Capture Technology in Construction

3D laser scanning creates a digital representation of physical construction conditions which can be used, shared, and analyzed. The process is simple: scan, register, process, model, check, and collaborate.

The maximum benefit of the technology lies in its connection with BIM, CAD, construction project management, and facility management systems. As autonomous robots and drones replace the process of scanning, and AI software automates the process of converting point clouds into BIM, 3D laser scanning technology will become more and more widely adopted.

Companies need to start with a clearly identified use case – renovation documentation, checking construction progress, or as-built BIM documentation and develop capabilities in this area.

3D laser scanning is not just an advanced surveying technology but a basis for more accurate and data-driven construction projects.

Ready to Transform Your Construction Projects With 3D Laser Scanning?

Accurate site data is the foundation of successful construction. Regardless of whether you are going to renovate, document your project in as-built BIM, or avoid unnecessary rework and delays in your construction projects, Camellia Buildtech is here to help.

Frequently Asked Questions

1. What is 3D laser scanning in construction?

3D laser scanning is a technology that allows recording the geometry of the construction project, building, or structure using laser measurements. The recorded measurements form a point cloud that may be converted into drawings, 3D models, and as-built BIM documentation.

2. What is the accuracy of a 3D laser scanner?

The accuracy may vary depending on the scanner itself, distance, calibration, environmental conditions, type of surface, scanning method, and operator’s experience. However, under suitable conditions, professional scanners may provide millimeter-level accuracy, but the required accuracy needs to be checked in advance.

3. How is laser scanning used for as-built BIM?

With the help of the scanner, the existing conditions of the building are recorded as point-cloud data. The next step is registration and cleaning of data, followed by importing the data into BIM software and modeling of walls, floors, structural elements, and MEP systems. The result is the as-built BIM model of the building.

4. What is the difference between laser scanning and traditional surveying?

Traditionally, the surveying process may include collecting selected measurements or points, while in 3D laser scanning, all visible surfaces are recorded, which provides greater geometric context and saves time on repeated site visits. At the same time, some surveying work may still be required for control, boundaries, and some measurements.

5. How expensive is 3D laser scanning?

The cost depends on such factors as the size of the project area, complexity of the site, required accuracy, number of scanning locations, deliverables, travel, and BIM modeling. Instead of buying a whole scanning system, companies may save money by renting the equipment or contacting a specialized scanning company.

6. What are the major limitations of 3D laser scanning?

3D laser scanning needs line of sight, so it is not able to capture hidden geometry behind walls, objects, or equipment. It may involve high expenses for equipment and processing, large datasets, specialized knowledge, anddifficulties associated with reflective or transparent surfaces. Acquisition of data takes time, and processing a large amount of data is time-consuming.