Optical techniques for multiscale damage assessment

Remotely sensed optical images coupled with advanced analysis techniques provide critical information for pre-disaster hazard and post-disaster damage assessment. Utilizing optical techniques, such as Light Detection and Ranging (LIDAR) and satellite imagery, this paper presents several geohazard studies with a broad range of scales, from regional to local component. In this analysis, a common workflow emerges, namely: (i) site survey, (ii) data acquisition, (iii) post-processing and (iv) analysis and interpretation. The end result will depend largely on the scale and type of hazards, degree and extent of damage, and acquisition method. Results from several case studies are presented that reflect this diverse dependency. These case studies include damaged structures from the Indonesia and American Samoa tsunamis, San Diego coastal erosion, and cracking of a historical building in Italy. The results show that recently developed change detection algorithms can quickly provide regional damage information if optical imagery is available. The development of a rich database of baseline information is critical for geohazard analysis. Frequent monitoring provides valuable data for hazard assessment, evaluation of building conditions, and full-scale testing.