About This Project
South Dublin County Council contracted Murphy Surveys to provide mapping of the M50 motorway interchanges for detailed as built surveys including drainage. The most important element of the project was that traffic should not be interrupted during the course of the survey. The client also required production of a 3D design model for specific sections of the motorway. The accuracy required for the final survey data was +/-10mm. This was achieved and verified using ground control placed in safe locations along the survey areas.
All surveys were carried out using a vehicle based mobile mapping system. The vehicle travelled through the survey areas at normal traffic speeds without impeding live traffic on the motorway. Complete 3D survey data was captured using laser scanners, photos and video, and was post-processed to detailed autoCAD outputs with 3D modelling output for specific sections. Final survey data had an accuracy of +/-10mm.
Data Processing & Quality Control
Following the field collection of data with the mobile mapper, all photography, GNSS positions, IMU positions and Laser Scan data was downloaded from the hard drives and computer system contained within the vehicle. The IMU and GNSS solutions were processed using a software package called POSPac. This software allows the Laser Scan data and photos to be geo-referenced for further processing. In the Roadview software the Laser Scan data and multiple photographs of the same view were incorporated together to create a raw 3D point cloud. This point cloud was then exported into conventional Laser Scanning processing software such as Leica Cyclone Topo 2. All line and points symbol data were extracted and exported into AutoCAD 3D for delivery to the client. The 3D point cloud and 3D design model for specific sections were also provided as a further deliverable to the client.
– 3D AutoCAD mapping
– 3D Model suitable for use with AutoCAD Civil 3D
– ASCII file of surveyed points
– Oblique photography – 5cm GSD
– Photographic inventory of sign faces and assets
– Processed Laser Scan point cloud suitable for import into autoCAD civil 3D
South Dublin County Council
3D Laser Scanning
38km (M50 Interchanges N4, N7 and Ballymount)
Mobile mapping vehicle equipped with multiple sensors including survey grade Laser Scanners, video cameras, photo cameras, survey grade GNSS and military grade IMU