The arena of geospatial data collection has undergone a radical change within recent years
There are technological advances in laser, positioning and radar technology leading to greater opportunities for mass data collection. Think of the upcoming revolution with driverless cars, whereby vehicles are constantly capturing data to geo-reference themselves and ensure that they know where they sit within the world around them.
Now imagine a world where all of that data is not only captured for positioning purposes, but also fed back into a larger system to create a continually updated mapping database. These technologies are still emerging, and much development needs to be undertaken before they become a reality in the wider world.
However, we are now at a point where many of these techniques are being employed by specialist survey contractors to capture above ground and subsurface details across the rail network.
So what impact is the emergence of mass data collection going to have on the geospatial industry as a whole? Bridgeway Consulting Limited’s (BCL) Geomatics Team has been proactive in researching, trialling, and adopting new and emerging technology for use on rail and other infrastructure projects. This often requires a sea change in the methodologies used for surveying, which in turn leads to the upskilling of staff, implementation of new processes, and the addition of extra quality assurance checks.
Survey techniques have evolved significantly over recent years. Traditional survey techniques involve high precision, often painstaking, measurements of angles and distances which are generally undertaken by a surveyor and an assistant. Time on site can be long, and data is then processed in the office relatively quickly. With the introduction of laser scanning techniques though, the ratio of site to office time has changed.
Now, huge amounts of data are collected quickly and efficiently in the field. Processing times however have increased, as time needs to be spent taking all of this data and creating something that is valuable to the end user.
Data collection techniques
The BCL Team are fully experienced in the use of multiple mass data collection techniques, having substantial operational experience on challenging and high profile projects. BCL currently offers the following techniques, and is constantly reviewing alternative technologies as they are developed:
- Vehicle Mounted Mobile mapping – whereby an integrated GPS, IMU and LiDAR unit is mounted on a road vehicle and driven through a site, collecting geospatially accurate pointlcoud data
- Rail Mounted Scanners – BCL uses the most up-to-date track measurement devices with integrated laser scanners to capture mass data, including gauging and height and stagger information, in one pass
- Handheld and backpack mounted scanners – largely for use collecting internal survey data, this is a very rapid data collection method which can be used to generate plans, elevations and 3D models
- Mobile Ground Penetrating Radar – whereby multiple GPR sensors are towed behind a road vehicle, geo-reference through GPS and IMU, and used to detect subsurface services, drainage and voids
- Terrestrial Scanners – where high accuracy surveys are required, then terrestrial tripod mounted laser scanners are often the best approach. While time in the field can be longer, the resulting pointcloud can be denser and achieve higher accuracies than with mobile systems
- UAV LiDAR and Photogrammetry – UAVs (Unmanned Aerial Vehicles) are being used more and more across the rail network. BCL has extensive experience in collecting survey information using LiDAR direct measurement and photogrammetric methods mounted on UAV platforms
- Ground Truthing Services – BCL provides ground truthing services to verify the accuracy of mobile mapping data. This often takes the form of targeted terrestrial laser scanning or Total Station measurements, which are then compared geospatially to the mobile data.
Mass data collection has multiple benefits, with perhaps the most obvious one being the introduction of safer methods of working. By reducing the time required to capture site data, there is a correlation with a reduction of putting surveyors in hazardous environments.
Additionally, by using vehicle or even UAV mounted LiDAR, boots on the ground can be drastically reduced. Extra benefits include a reduction of planning time and associated costs by requiring fewer shifts within possessions or traffic management, the reduction of the potential of human error, and more complete datasets captured on site.
On top of all of the above, with large datasets are captured on site, then detailed analysis can be carried out in the comfort of an office environment. While the techniques above have clear benefits, they can also introduce additional challenges for the survey contractor and end user. Any survey method has its limitations, and mass data collection techniques can suffer from line of sight issues.
Essentially, any scanner can only survey what it can see from its location – it will not see behind structures, around corners, or through vegetation. The argument of speed vs accuracy is also one which should be taken into consideration. Generally speaking, the higher the speed that survey data is collected, the lower density and accuracy is achieved. As technology continues to improve, this will undoubtedly be resolved, but at present the best approach is often a combination of multiple data capture techniques.
Turning data into deliverables
While the majority of this article has addressed the potential benefits of mass data capture, there are still a great number of occasions where a more traditional survey method is still the best approach.
BCL Project Managers work with clients to ascertain exactly what level of detail is required, and to establish the best method for capturing that detail. For example, for smaller, discrete sites, or heavily vegetated areas, a traditional approach may well be the most cost-effective way of delivering the survey requirements.
It should be noted that for all of the data capture techniques mentioned above, it is important to apply basic survey principles at the very beginning of a project to ensure that the correct accuracies, data coverage, and quality can be achieved.
This is where BCL’s Geomatics Team can further help. With an extensive underpinning knowledge of the geomatics field, BCL will ensure that a project is planned and executed in a coherent way, installing suitable levels of survey control and verification measures to ensure that the final deliverable meets with industry standards and the client’s needs.
While the collection of huge datasets provides real benefits, it can also be a challenge to turn the data into a deliverable that the client can use. Large datasets require significant investment in both IT hardware and software, and it is here that BCL ensures that the data delivered can meet a client’s expectations.
This might include separating datasets into smaller individual chunks, the provision of on line data viewer tools, wireframe data extraction and 3D modelling. If clients are unsure of which software to purchase, BCL offers advice and training to ensure that end users can get the most from the datasets that we deliver.
BCL’s approach to data collection is relatively simple. It asks that clients come to with problems that they need to solve, and BCL can find the most efficient way of gathering and processing the data required for their projects.
For more information or guidance on mass data collection techniques, please contact Richard Cooper, Geomatics and Examinations Director, at Richard.email@example.com.