Development of an UAS for post-earthquake disaster surveying and its application in Ms7.0 Lushan Earthquake, Sichuan, China

• UAS is used for early impact analysis after an earthquake.
• An example of UAS is developed for rapidly obtaining disaster information.
• The optimum parameters for different imaging resolution requirements are obtained.
• A photogrammetric workflow is applied to cope with the acquired disaster images.
• The system is applied to Ms7.0 Lushan Earthquake, Sichuan, China.

The main objective of early impact analysis after a disaster is to produce georeferenced data about the affected areas, in support of humanitarian action. Crucial information is the identification of the disaster areas and the estimation of the number of people involved. Satellite imageries are mainly used as input data for early impact analysis in medium and large scale map. Analyses aimed at defining the damages of infrastructure and/or to facilities require suitable data, such as high resolution satellite images. Unfortunately, satellite images are not always available in a few days after the event. Therefore in situ surveys are preferred. Innovations in Unmanned Aircraft System (UAS) have allowed them to become valuable tools in capturing and assessing the extents and amount of damages. Flexibility, safety, ease of operation, and relatively low-cost of ownership and operation facilitate UAS implementation in disaster situations. In this paper, an example of UAS was developed for rapidly obtaining disaster information. Data acquisition at specified scales was successfully performed with the chosen fixed-wing UAS. For the image analysis, a photogrammetric workflow was applied to cope with the very high resolution of the images acquired without ground control points. Tests showed that the system plays an important role in the work of investigating and gathering information about disaster in epicentral areas of the earthquake, such as road detection, secondary disaster investigation, and rapid disaster evaluation. It can effectively provide earthquake information to salvation headquarters for swiftly developing the relief measures and improving the efficiency of emergency rescue.