Linear infrastructure mapping using airborne video imagery and subsequent integration into a GIS

Airborne video imagery is an ideal tool for acquiring the spatial data needed for mapping linear infrastructure features. The flexibility offered by helicopter based digital video sensors means that high resolution colour imagery can be acquired of long linear features quickly and cheaply. This paper describes how airborne video has been implemented in Australia to map powerlines, and subsequently how the map products have been integrated with vector data and ground measurements to create a detailed spatial information database of the power distribution network. Strip maps are created from downward looking video sequences by mosaicing captured images using a combination of ephemeris data with area and feature based matching. Absolute orientation of the image mosaics is carried out interactively using the locations of the pylons as ground control points. An assessment of the resulting mosaics showed that the accuracy of the rectification of the image sequences was acceptable for purposes of this project. The georeferenced strip maps were imported into a GIS, the design of which allows the operator to view an image map of any part of the entire powerline network with digital topographic data overlaid. Selecting particular points on the image map provides access to information such as tower type, location and height. In addition, the operator is able to view a movie clip of any part of the powerline and surrounding terrain, from either a downward or forward looking perspective.