What is a 3D Laser Survey?

A 3D laser survey is the modern alternative to traditional-style surveying methods. It offers a variety of benefits, allowing a surveyor to quickly and easily collect a large amount of detailed data over a short period of time. In this post we’re addressing the question, “What is a 3D laser survey”, answering commonly asked questions and looking at how 3D laser scanning is used throughout the construction process.

First question – what is a laser survey?

A 3D laser survey utilises high-definition LIDAR (Light, Imaging, Detection and Ranging) technology to capture millions of points that depict a structure with precision and in high detail.

The data captured from numerous individual scans is stitched together or ‘registered’ to create a homogenous point-cloud. This point-cloud forms the foundation to produce detailed and accurate useable drawings (2D plans, cross sections and elevations), as well as the ability to model the external and internal features of a structure accurately in 3D.

Compared to traditional methods of surveying (hand sketching and manual measuring), 3D laser scanning offers the ability to capture vast amounts of data – both accurate and detailed – in a very short space of time.

What is a laser survey

How are surveys produced from a 3D laser scan?

The 3D laser scanner measures millions of discrete data points within its field of vision, each recorded with X, Y & Z co-ordinates, as well as the reflective intensity and colour of the scanned surface.

Numerous individual scans taken around and through a site or structure are brought together and carefully registered with millimetric precision within specialist software. Registration can be undertaken with either cloud-to-cloud (C2C), or by use of spheres and targets, common between scans, to ‘resect’ each scan location.

3D GPS (or other local-grid) references can be allocated to the data to move and rotate in computer-space to enable spatially-correct location. The homogenous point-cloud can be exported and inserted into CAD (computer-aided design) or 3D modelling software.

The CAD software has the ability to ‘slice’ the point-cloud data into useable portions. Lines and planes are formed within the CAD/modelling environment to coincide with the sliced point-cloud and, if staying diligently faithful to the point-cloud data, will build up into a fully detailed, accurate representation of the scanned structure, with as much or as little detail shown as required.

There is no magic button (yet) that can automate the process with the level of accuracy demanded by architects and engineers today, although Artificial Intelligence may have a lot to offer in that regard in coming years. The accuracy of a survey, produced from scan data, depends on a chain of processes, each of which requires careful attention, skill and experience to get right. Of particular importance are:

  • The density and choice of scan locations (stability, proximity, environment, scanner limitations)
  • Scanner settings (resolution and scan quality, weighed against time constraints)
  • Registration method (C2C or target registration, and a knowledge of the software algorithms to employ a methodology beyond the two options to achieve the best results.
  • Determination of GPS references on site (using a combination of GPS and Total Station equipment for best accuracy).
  • Interpretation of point-cloud data within the CAD environment and production of line work / models faithful to the scan data.

Building blueprints with images of buildings.

Why are 3D laser surveys so beneficial?

3D laser scanning has become the preferred method of data capture for measured surveys for various reasons.

Firstly, it allows for rapid data collection, with vast quantities of data captured in minutes. Secondly, it is able to capture the small elements of the survey in fine detail.

Inaccuracies in measured surveys can result in raised costs and frustrating delays, as well as the potential for failing to comply with planning conditions.

3D scanning technology ensures the most detailed and precise data sets are produced, which can confidently be used as the foundation for core design and development plans.

One of the major benefits of a 3D laser survey is the way it goes beyond depicting walls, windows and doors to produce data that is detailed enough to allow clear sight of internal and/or external features in exceptionally high resolution.

Anything from individual bricks, power sockets, exposed wires and architectural mouldings can all be located and detailed. Furthermore, by default, a scanner will capture data in a sphere around itself whether or not the information is initially required. This means that any information required subsequently can be pulled from the data with no site revisits, saving time and money.

Also worthy of mention are the safety benefits. The 3D scanning process is contactless, meaning there is no need for physical access to a building to take measurement. If we can see a feature, we can scan a feature. It also means hazardous environments can be measured from afar without throwing up a safety risk.

What is a 3D laser survey

What is a laser survey’s role throughout the construction process?

A 3D laser survey can be used at various points throughout the construction process.

Pre-construction, it can be used to confirm existing site conditions, and to form the basis for models, plans and records going forward.

Because the laser survey so accurately records existing conditions within a building or the wider built environment, the data can be used to generate 2D plans or 3D models which can be used, much like a digital twin, as a reference point for any proposed changes.

During construction, 3D laser scans can be used to check progress and build accuracy of the project against the intended design. This ability to compare actual site data against proposed elevations, sections and footprints is hugely important in terms of quality control.

Post construction, project management teams can confirm that the resulting physical structure actually matches the originally proposed design. A final 3D laser survey can be carried out at this point to create an as-built model which can be passed to facilities and building management teams to help them carry out their ongoing roles.

What is a laser survey

Looking for quality 3D laser surveys in London?

At Callidus Surveys, we’ve invested in the highest specification leading-edge 3D scanning equipment and software for the finest detail and accurate laser surveys achievable. So you get everything you need to make sure any drawings delivered from your office are based on the most accurate survey data, and in the fastest possible timescale.

What’s more, we offer a unique ‘whole building’ approach to our measured surveys, which means that any building is depicted in computer space as a whole, interconnected built structure – as it is in reality – and not just a series of independent drawings. It is useful to remember that a CAD operator is not necessarily a surveyor, and the Callidus surveyors are much more than draftsmen. At Callidus you get the professional service.

With decades of experience, and a team comprising some of the best-trained laser surveyors in the UK, you’ll enjoy an efficient, hassle-free service. So, you can focus on your to-do list, and leave the deadlines, and the detail, to us.

Need a 3D laser survey? Simply send us your specification and we’ll get back to you with a quote for your 3D measured survey.


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This post was written by

Andrew Wilson
Andrew is the Survey Manager and Director at Callidus Building Surveys Ltd.