Reducing the cost of multi-spectral remote sensing: combining near-infrared video imagery with colour aerial photography

Land managers are often confronted with management problems that could be addressed using decision support or management information systems. The use of such tools, however, depends on the availability of appropriately resolved spatial data. One source of such data is multi-spectral remotely sensed imagery. The cost of such imagery, particularly where environmental goals are most important, is often prohibitive. Even when the cost of such imagery can be met; other factors, such as cloud cover for satellite-based systems or sensor scheduling for sophisticated airborne systems, may mean that imagery is not available. This paper investigates the utility of a system that combines near-infrared imagery from a video camera with conventional medium-format aerial photography deployed in a light aircraft platform. Previously, imagery obtained from video cameras has suffered from limited spectral range and from significant image motion effects. These problems were eliminated by the use of an electronic-shutter charge-coupled device video camera with a strong IR response. The systems components and the approach to their operational deployment are described and the options, for transforming the raw imagery into survey coverage discussed. The image quality and cost is presented for a site characterisation application where the aim is the generation of normalised difference vegetation index values. It is concluded that the system has significant potential-utility for decision support and land-management applications. (C) 2002 Elsevier Science B.V. All rights reserved.