What Is A Point Cloud Survey?

What is a Point Cloud Survey?

A point cloud is a collection of millions of different measured data points displayed in 3D and captured using high tech laser scanning equipment. These data points are all extremely accurate positional measurements that come together to form a visual of a site or structure. They can be used to draw 2D plans or develop rendered 3D models of a site or structure.

What are the benefits of point cloud surveying?

The technology used in 3D laser scanning makes it an excellent starting point for construction projects. Construction professionals using point cloud surveying alongside traditional land surveying techniques can collect more accurate data.

High accuracy and detail

Each point cloud scan taken on site can achieve an accuracy of within 2mm and the laser scanner picks up everything in its line of sight. The point cloud includes a record of everything from light switches and sockets, architrades and fixed furnishings as well as walls, floors, ceilings, door and window openings.

Faster data collection

Using a laser scanner to survey a site significantly reduces the time it takes to gather data. The scanners used to create a 3D point cloud can gather between 50,000 and 2 million data points per second. While specific timescales can differ depending on the site or the amount of detail needed, laser scanning technology can make the surveying process much quicker.

Safety

Laser scanners are small enough to be mounted on tripods, drones, or vehicles. This enables land surveyors to use the scanners on sites that would otherwise be dangerous or inaccessible. This can include unstable heritage sites, busy industrial sites, or harsh terrain.

Collaboration

Point cloud data can be shared with others, allowing multiple disciplines to have access to one single accurate data set. Working digitally in this way can be significantly faster than working with paper or simple CAD drawings.

Futureproofing

A comprehensive point cloud survey includes a large amount of data. Even if this information isn’t needed at the beginning of your project, having it on hand means you won’t have to physically return to a site in future. A point cloud can also be used for clash detection or to create a digital twin. These can be used to help foresee any future issues on the project.

What are point cloud surveys used for?

While 3D Laser Scanning has been used by the land surveying industry since the late 1990s, it is now part of the everyday kit of most land surveyors. This has been driven by the increased accessibility of laser scanning equipment in terms of cost and portability, as well as a growing demand for 3D point cloud surveys.

Measured Building and Topographical Plans

3D point clouds can be used to produce 2D measured plans including floorplans, elevations and cross sectional drawings. The point cloud data can also be used alongside traditional topographical surveys to produce accurate and detailed topographical plans.

Volumetric Surveys

A point cloud can be used to provide reliable and accurate measurements of quantities of materials. Volumetric surveys are required for quarry operations, landfill monitoring and auditing, as well as construction projects. They involve carrying out a 3D laser scan of stockpiled, extracted or collected materials and aggregates stored on site.

Clash detection

Clash detection is the process of comparing and overlaying designs onto survey data to make sure that there are no conflicts between the two. Point clouds can help to prevent costly rework or material waste if the design and scan do not match.

As-built documentation

As-built documentation provides a comprehensive drawing of a building post-construction. People use these drawings to compare the actual building with the plans for accountability or legal compliance. Using point cloud surveying can help to make sure that these as-built drawings are as accurate as possible.

Heritage documentation

Heritage documentation is the process of recording, archiving and measuring historical sites. This information can then be used for conservation or renovation. Heritage documentation can also feature material properties or can track structural decay.

Land surveyors can capture data for complex or extensive heritage sites using 3D scanners. Laser scanning can also be done by drone, which makes it an excellent choice for sites that are potentially hazardous.

Collaborative BIM Models

Building Information Modeling (BIM) is the digitisation of the planning, design and construction process for development. This allows a multidisciplinary team to work collaboratively by sharing their work in real time. It can be used to plan, run simulations, track budgets, project manage and manage health and safety.

This is enabled by the consistent data set provided by the point cloud survey of an existing building and structures at the beginning of a project. There are six levels of development of a BIM Model from conceptual design through to construction and post completion.

Digital twins

A digital twin is a virtual replica of a building. This is consistently updated and is a real time ‘twin’ of the structure’s current condition and layout. Digital twins use data sets from various sources to first create and then to keep the model up to date. Using point cloud surveys as a basis for creating a digital twin can help to build a precise replica which is then updated as the structure changes.

How long does a point cloud survey take?

Laser scanners can capture millions of data points in seconds, so on-site survey times can be significantly reduced when compared with traditional survey techniques. A number of factors can influence exactly how long this type of survey can take, including:

• Size of the site: Small sites can be scanned in a couple of hours while complex buildings could take several days.
• Level of detail required: High-detail scans or scans including colour can take longer to complete, process, and create a model for.
• Processing time: Producing the final model can take up to 3 days for smaller projects and can be up to 10 days for complex projects.

A surveyor will be able to give you a more specific timeframe for your project when they have seen the site and collected all of your details.

How do land surveyors carry out point cloud surveys?

Point cloud surveys are conducted using a 3D laser scanner as well as a GPS kit and Total Station. Ordnance Survey co-ordinates are used as fixed points, along with targets that have been positioned using the GPS kit and Total Station. This creates a framework of reference points that ensure that all spatial data is consistent, accurate, and mapped to recognised co-ordinate systems.

The surveyor will then take scans in a methodical grid around the site or building. This process is repeated at points throughout the site, until the entire space has been scanned.

Back at the office, the scans are downloaded and stitched together using processing software. This creates the combined point cloud where each point in the scan has a real world co-ordinate. The point cloud can then be shared as it is, or we go on to produce 2D plans such as floor plans, elevations and sections or volume calculations.

How much does a point cloud survey cost?

The cost of a point cloud survey can change depending on a variety of factors in your site. A surveyor will be able to give you an accurate quote based on your project requirements and the site that needs surveying.

What influences the cost?

• Size of the site or building
• Level of details required
• Site complexity
• Deliverables

Whilst point cloud survey can be provided on their own, many land surveyors offer point cloud surveying as part of a package. For example a measured building survey includes a point cloud survey to capture the site data, but the deliverables include 2D floor plans, cross sections, external elevations or roof plans. Measured building surveys can start at £1500 + VAT for a basic survey up to £7500 + VAT for a large industrial property.