Aerial photography might seem an unlikely tool for the location and mapping of underground infrastructure, but a particular form of aerial photography from Australian company NearMap is proving to be a useful tool.
NearMap specialises in producing highly accurate, and frequently updated, aerial maps. It flies urban areas in Australia, New Zealand and the USA multiple times per year, processes massive amounts of visual data, and uploads up-to-date aerial maps to the cloud within days. These can be accessed by clients from its proprietary browser.
It produces three types of images:
- NearMap Vertical, looking straight down with a claimed accuracy of 15cms.
- NearMap Panorama which multi-perspective aerial views of urban areas with uninterrupted pan and zoom capabilities
- NearMap Oblique, which provides high-resolution photogrammetry and multi-perspective aerial views of urban areas. NearMap says the service enable precise measurement of locations or features in three dimensions.
When NearMap Oblique was launched, in July 2017, NearMap CEO, Rob Newman said it “maps reality, by capturing the tops, sides and view angles of locations, buildings and objects, providing specific details of exactly what’s on the ground.
“Users can immerse themselves in 3D textured mesh models, improving analysis and design activities. They can see different elevations and line of sight using the 3D information. These features become important in many use cases including airport or utility planning, or to determine the best location for a crane before a construction project.”
NetMap claims that its imagery, while not considered survey grade, is “so close that utility risk companies are effectively using it to track underground infrastructure.”
A case study on its web site relates how US company Hydromax previously used satellite imagery to visualise the environment around buried infrastructure.
It explains: “These sources were out of date and lacked the quality and resolution necessary to identify key features. For example, one of the services Hydromax USA provides identifies a problem known as a ‘cross bore’ [that] occurs when a gas line runs through a sewer pipe creating risk that the gas line could rupture and leak into sewer or water lines.
“Outdated, low-resolution imagery made it difficult to identify the exact location of these cross bores in relationship to buildings and ground conditions above them. New construction or buildings were often missing or not clear enough to assess real risk and this impacted resource deployment in the field.”
NearMap says that, by implementing its high-resolution PhotoMaps, Hydromax USA increased the accuracy of its data collection, reduced time spent in the field, and improved client satisfaction with higher quality reports.
Chris Blohm, data analyst manager with Hydromax said: “NearMap dramatically simplified things for us, allowing us to make more accurate decisions. With NearMap, we can actually see exactly where the bore points are. That really helps us narrow down where a gas line is located and which buildings we need to inspect.”