Scan till you drop
Chapter 2: Scanning, modelling with confidence
Scanning, modelling with confidence
Project Surveyors used a variety of Leica Geosystems solutions to capture, model and analyse the data. Starting with the Leica ScanStations C10 and P20, the surveyors were able to capture minute details. The Leica ScanStation C10 was used for the external facades and inside for large structures, such as the parking garages, due to its long-range capability.
Inside, the Leica ScanStation P20 was used for its quality of producing fast reliable data at low resolution.
“The fast scanning time of the P20 helped us improve site workflow, increasing the number of scans per day fourfold,” said Jackson.
For survey control, Project Surveyors used the Leica TS15 and Leica Nova MS50 MultiStation. The MultiStation was also used to scan windows for simpler capturing. Establishing a survey control network around the perimetre of the site and throughout the shopping centre at each level, these instruments ensured millimetre precision for aligning scans of the retrofitting construction. Laser scan targets were coordinated within the control network to maintain the accuracy of the overall point clouds.
A total of 3,700 scans from 55 days on site resulted from the project. The point clouds from these scans were cleaned and registered using Leica Cyclone 9.0. The entire process only took 20 days due to the addition of the auto-alignment registration within the software. Compared to point cloud-to-point cloud visual alignment, which would take around two minutes each to visually find common points, auto-alignment only takes 30 seconds to one minute.
“The time does not sound like much for a few scans, but when we’re talking about thousands of scans, this becomes a significant amount of time saved,” said Jackson. “With these savings, we were able to increase our productivity by at least 50 percent.”
The firm also used Leica TruView to provide the architects with the point cloud data so they could overlay in the model and have extra information, such as dimensions they needed to extract for accurate and realistic planning.
“Leica Truview images were a deliverable for the client, but they also helped the modeller to have a complete understanding of what they are modelling over,” said Jackson.
Autodesk Revit 2014 was used to model architectural elements while Autodesk Revit Mechanical, Electrical, Piping (MEP) was used to create pipes, plant, ducts and other services to create a partial MEP model of the loading docks. As the size and detail of this project would have taken one modeller 120 days to complete, Project Surveyors worked with a team of modellers in collaboration on one central model across a wired and large-data network.
Using the export option in Leica Cyclone 9.0, the surveyors exported the point clouds either separately as binary ptg files or unified as pts files. Autodesk Recap was then used to convert the files into Autodesk-compatible rcs files, which could then be inserted into Revit and modelled over. Using Leica Cloudwork for Revit, Jackson added that the exportation and conversion steps of the workflow would be eliminated, providing modellers with point cloud conversion tools as well as a single master data source rather than multiple files and versions of files to deal with.
“Using this laser scanning technology, we have won similar large projects, such as one in Sydney where we’re working with the same consultants who used this model as an example to the project owner of what they required as survey information,” said Scott Deveridge, Project Surveyors director. “Referrals to provide a similar service on another challenging project is the best feedback we can get.”
Explore next chapter: Lessons learned from HxGN Live