Case Study: Terrestrial Laser Scanning
During 2009 Infoterra Ltd undertook a survey of the Walkers Stadium in Leicester; this involved a combination of Terrestrial Laser Scanning, Mobile Laser Scanning and airborne LiDAR acquisition and processing.
The outside of the stadium was scanned with Infoterra’s mobile laser scanning system and the Terrestrial Laser Scanner utilised for fine detailing. The inside area of the stadium was captured from a serious of 7 scans using the Terrestrial Laser Scanner. The scanner positions were referenced to the National Grid System using GPS techniques and the Leica GPS SmartNet service. The Terrestrial Laser Scanning survey took a two man team, two days to acquire. The mobile point cloud – of the outside of the stadium - was collected within a few hours.
The raw point cloud data sets created from each of the terrestrial scan positions were aligned to each other and then referenced to the National Grid System using RiScan and Polyworks software tools. Once the point cloud data was aligned PointTools and Rhino software was used to extract relevant three dimensional vector data, of the main features such as the pitch, the stands and the structure of the stadium. The combined point clouds from the Terrestrial Laser Scanner and mobile capture were jointly used to generate a 3D surface model / wireframe utilising PointTools software. The final extracted line work and the 3D surface model were then combined to create a final three dimensional model of the Walkers stadium.
The relative accuracies of the point cloud data created from the Terrestrial Laser Scanner was +/- 5mm in both plan and vertical with a final absolute model accuracy of +/-15 mm in plan and +/-30 mm in vertical. This was relevant to the project specification and higher absolute accuracies could have been achieved if necessary.