Infrastructure

The extremely high point densities of elevation data collected with today's high repetition rate airborne laser scanners (Lidar), makes them an ideal tool for mapping, planning, maintaining and managing infrastructure such as dikes, dams, roads, railways, pipelines and power lines. Given the economic importance of such facilities and the growing adoption of GIS as a management tool, the ability of laser scanning to rapidly generate high accuracy, high density data that realistically represents the structures in 3D, makes it a powerful tool for infrastructure mapping and management, even more so when combined with the simultaneous capture of digital imagery.

Traffic and roads

Maintaining existing roads, increasing their capacity and developing new infrastructure is vital for any society in order to meet our rapidly changing transportation demands. Lidar data and the products provided by the digital camera provide a good base for efficient planning and the extension and maintenance of infrastructure. The British Highways Authority awarded us a 5-year contract to scan a huge part of their highway network in a very high resolution in x, y and z. We use a helicopter system and a fixed wing airplane for the acquisition of the data, the required point density of 24 points/m2 and a pixel resolution of 3.5 cm for the digital camera data are challenging specifications we were proud to meet. The data is processed in-house with our own processing chain and delivered in various formats for further usage including the mx-genio format. The Highways Agency will be able to access information for a whole range of purposes including geotechnical management, noise modelling, environmental management and incident analysis.

These new surveying methods will speed up the delivery of major road schemes by reducing the time taken to produce the data. Safety is another very important reason for choosing this technology. Measurements on the roads or bridges itself are no longer necessary and the surveys do not require lane closures nor cause delay to drivers.

Power line mapping

With a high repetition rate sensor, the laser point data can be sufficiently detailed that individual power line cables can be observed. When performing a power line survey, laser pulses reflect from the ground, other pulses reflect from undergrowth and encroaching vegetation and others reflect from the power line cables, pylons and towers. Laser scanning enables facilities managers to simultaneously acquire data from the power lines, from the vegetation beneath it, from the pylons and towers and from the ground, faster and more reliably than through traditional techniques.

The data can be used as input for further modelling using specific software including PLS-CADD for transmission line design and line-rating studies.

From the points reflected from the power lines, it is possible to determine the cable position as shown by the figure. Once the position of the cables is known, the relative position of the cables with respect to the vegetation can be visualised.

Dikes

The maintenance of existing dikes and the planning and adjustment of new dikes to protect land and lives is a challenging task for all administrations involved. The traditional method for dike surveying has been terrestrial measurements.

TerraImaging uses its experience and approved laser-scanning methods to scan large parts of the existing dike infrastructure in the Netherlands. The helicopter-based data acquisition delivers high quality and high resolution elevation information. In addition to the elevation data high resolution orthoimages and video data is acquired.