Development of a helicopter-based integrated system for avalanche mapping and hazard management

Natural hazard mapping requires techniques that can provide accurate and sporadic geo-referenced data. When facing difficult accessibility of the terrain and large mapping areas, the aerial photogrammetry offers the best solution to this problem. Nevertheless, in the domain of avalanche studies the classical photogrammetry reaches its limits when volumes of snow are the parameters to be determined. The difficulties of installing durable signalization in such areas initiated the development of a system that uses a navigation solution to determine the parameters of exterior orientation. It integrates light aerial camera, GPS and INS components to a platform that is free of the helicopter in 6 degrees of freedom. Experimental studies performed in the avalanche test site of "Vallée de la Sionne " allow determining the correct ratio between the system accuracy versus its flexibility. The system should be as light and flexible as possible whereas the accuracy of the camera projection centre should at the 15-20cm level in position and 0.005-0.01 ° in attitude. The paper presents the analyses of the experimental results using the photogrammetric solution over the avalanche test site and describes the individual components of the system in development. 1