3D LASER SCANNING
Part of our Data Acquisition Solution
Our high-definition 3D laser scanning surveys offer an alternative to traditional survey methods. Providing accurate and rapid data capture with a comprehensive level of detail, particularly valuable for building and civil engineering projects.
What is 3D Laser Scanning?
A 3D laser scanning survey enables us to capture information within line of sight without the need for direct access, making it an ideal solution for reducing risk in high-hazard areas or avoiding work at height. The resulting point cloud data, comprising millions of data points, can be used to construct detailed 3D models. Each scan takes just minutes to collect the data and is fully georeferenced during the registration process.
Vast amounts of data can be captured quickly, which can offer benefits in respect of both the redundancy of data gathered and potential for reduced access requirement and durations.
The versatility of laser scanning, combined with our experience and ability to operate in complex environments, ensures we can deliver accurate digital drawings across a wide range of sectors.
Benefits of 3D Laser Scanning
Accurate information
Rapid data collection – 1,000,000 points per second
Complete data – all information in the scan view is collected in just one visit and can be referenced to add further information to models and drawing outputs, in the event of any retrospective scope changes.
Risk reduction – makes remote surveys at hazardous sites possible and can reduce repeat returns to restricted locations
Data can be processed as required to fit into the priorities within a programme of work
Case Study: Bridge Structure BTW / 67
Key Project Details
Location: St Ives, Ringwood
Client: AmcoGiffen
Sector: Rail
Contract Value: £14,000
Services: Topographical, 3D laser scanning & river channel cross section survey
Central Alliance carried out a topographical survey of a historic railway structure that now forms part of a National Cycle Route, where the Castleman Trailway crosses the River Avon.
The brief required us to capture accurate and detailed information for the bridge structure and all landform within a 30 m radius. This included the approaches to the cycle route at deck level and the River Avon below.
We used terrestrial 3D laser scanning from both the deck and underside levels to record all structural elements. These scans supported the production of 2D general arrangement drawings and a 3D model, integrated with high‑resolution imagery.
Access Challenges
Surveying at deck level was straightforward. However, accessing the underside of the structure above the River Avon proved challenging. Steep slopes and dense vegetation restricted access to the riverbank and left very few suitable locations for capturing 3D scan data from below.
These constraints blocked clear lines of sight to large areas of the bridge underside. We therefore needed a different method to obtain full point‑cloud coverage and meet the specification.
We could safely access the river channel using an inflatable dinghy. This allowed us to survey channel details, including hard and soft bed levels, using conventional total‑station observations. We also surveyed cross‑section profiles at 10 m intervals.
We considered several options for underside scanning, including unmanned aerial surveys (UAS), mobile mapping from a small boat, and terrestrial scanning from a pontoon. None of these approaches could meet the required accuracy.
Inverted Scanning Solution
We therefore chose to use inverted scanning techniques and lower a lightweight 3D laser scanner from the bridge deck. Our team designed and built a davit‑arm system using inverted tripod components and a counterweight. This setup allowed us to stabilise the scanner on the deck, swing it safely over the parapet fence, secure it to the structure, and lower it beneath the underside of the bridge.
By completing several carefully positioned and gently lowered scans, we captured a comprehensive 3D point cloud of the bridge underside. We integrated this with the deck‑level scans by referencing common survey control.
After registering, georeferencing, cleaning, and colourising the 3D point cloud, we produced the required outputs: a detailed topographical survey layout drawing, a 3D structural model, sectional elevations, and watercourse channel cross sections.