Getting the Full Picture?
Virtual Immersion into an Accurate, Digital Representation of Site
08 October 2014
Ever forget to take a measurement from site and wish you could wander straight back out and get it? That's probably easy to do if the site is next door - and not in a different country or offshore. No problem if you can just stroll straight through the gates without inductions or permits! And let's assume there are no other work crews that have barricaded off the area you need making it impossible to access.
But when you finally make that measurement - say, a distance measurement from one steel column to the other, did you really get the full picture?
Intertek Surveying Services have been working with engineers and designers for decades all around the globe helping to provide correct measurements to support projects such as construction and integration of hulls and topsides for deployment to offshore locations, retrofitting FPSOs, modular fabrication of plants and large-scale laser scanning of refining complexes and their offshore facilities. Recently, we've been deploying our state-of-the-art surveying instrumentation to not only provide accurate measurements but also collect the full picture of the site. We aim to make a comprehensive digital representation of the site and seamlessly integrate it into the engineering and design workspace, such as intelligent CAD environments.
Our laser scanning instrumentation is fast and accurate (see our previous blog here). Collecting millions of 3D points per minute, our surveyors can quickly build up a 3D picture of the site. Our laser scanners are equipped with sophisticated cameras allowing colour mapping of the point clouds. The result is Figure 1.
Figure 1: Coloured laser scanning of piping from a gas plant.
This is a 3D point cloud and not a still photograph! We can make measurements in it, extract coordinates and elevations, zoom and pan around. The 3D visualisation is clear if we show the same scene rotated from a different viewpoint (see Figure 2) and, better, in a fly-through (see Figure 3). In Figure 2 our surveyors have also overlaid conventional surveying measurements into the point cloud. In this specific case, we have surveyed bolt locations using a very precise surveying method called dimensional control.
Figure 2: Integrating conventional surveying products with laser scanning.
Figure 3: Fly-through of a point cloud showing full 3D nature of the cloud. (HD)
To make sure our engineering and design clients really are getting the full picture, Intertek surveyors also prepare virtual site tours using high-resolution spherical photography. This is a package of numerous spherical photographs (i.e. 360° views) that allow zooming and panning to see almost anything at the site. The spherical photographs are hot-linked to a map or plan of the site for easy navigation. Figure 4 is a view onto the same pipe as Figure 1.
Figure 4: Fly-through of one of Intertek's spherical virtual tours. (HD)
Viewing the imagery is useful and we find that our engineers use it in cooperation with their design systems so they can visualise the designs of piping through cluttered areas, assess a zone for constructability and make screen captures for reports or work instructions. Our premium spherical viewing platform, NetView, allows measurements to be taken in the imagery. This product is viewed in a simple free viewer which means the whole project team - and not just the designers with specialised software and high performance computers - can interrogate the data.
Figure 5: Using scanner-based spherical tours to make real-time distance measurements and determining elevations.
Lastly, our coloured point cloud data are best used for integrating design CAD to assess for clashing and fit, or extracting as-built information for rapid back modelling. Figure 6 and 7 shows 3D as-built CAD data that were modelled from the Intertek point cloud.
Figure 6: Integrate design into the point clouds or extract 3D as-builts.
Figure 7: 3D As-built CAD modelling straight from the point cloud.
All of these data are accurate. Dimensional control accuracy is <±1mm and laser scanning accuracy is ±4mm. All survey datasets align firmly with the site or platform coordinate system and is confirmed in a published report. Surveying data need not be boring discrete point measurements! Engineers and designers benefit from a dense and rich coloured point cloud accompanied by a virtual tour. It means that the project team are rarely forced back out to site to collect a measurement so they can focus on designing. They are virtually immersed in the site from their desktops. Intertek is providing the full picture.
Stuart has been working in precise surveying, laser scanning and metrology for over 10 years in Australia, SE Asia and Africa. He has started-up the Australian operations for Intertek increasing our global reach to this region. Intertek Surveying Services (formerly Hi-Cad) are a global leader in dimensional control and laser scanning.