Seismic Disaster Information Extraction From Remotely Sensed Imagery

With the emergence of high resolution remotely sensed imagery and development of remote sensing information extraction technology in recent years, remote sensing, RS for short, became an effective means for acquiring seismic disaster information rapidly, emergency response and seismic disaster assessment. Due to lower accuracy of seismic disaster information extraction, singularity of seismic disaster recognition target and lack of complete remote sensing seismic emergency response software platform, this dissertation study on seismic information extraction method using remotely sensed imagery and its practical application. The main works of this dissertation are summarized as follows:1. Seismic information extraction method based on seismic disaster knowledge base and object-oriented image classification techniques are studied thoroughly.The key techniques of object-oriented information extraction are analyzed, including multi-resolution segmentation, quantitative description of image object features and fuzzy classification. The optimal segmentation scale model is presented using image object standard deviation and local Geary's C, which could make sure different scale factor for each ground object and is exact and efficient after validation. Furthermore, knowledge base about remote sensing seismic disaster is established. The structure and content of knowledge base are also described. Seismic information extraction work flow based on object-oriented change detection technique are presented, which would provide a basis for extracting seismic disaster information.2. Feature optimal scheme and reasoning rules are pointed out to extract building seismic damage information from different damage level buildings.Building seismic characteristics are thoroughly analyzed on remote sensing image. The corresponding relation between RS and macro-ground investigation building seismic damage level is confirmed, at the same time it is pointed that they are different from each other in judgment basis. Through theoretic analysis and tests, feature optimal scheme and reasoning rules are pointed out to extract building seismic damage information from different damage level buildings. Thereby, RS seismic damage knowledge base is established initially according to that scheme and rules, and thus the building seismic damage extraction accuracy is improved. In this dissertation, taking Haiti and Bam earthquake as example, different damage level building information are obtained using object-oriented classification and object-oriented change detection method.3. A new road extraction algorithm based on object-oriented change detection method using road vector data overlaid on post-earthquake image is presented.Difference judgment basis are studied as well as the corresponding relations between RS and macro-investigation damage level about road and bridge. Feature optimal scheme and reasoning rules are presented by analyzing the characteristics of road and bridge on RS images. A new road extraction algorithm based on object-oriented change detection method using road vector data overlaid on post-earthquake image is presented. This algorithm can realize quantitative analysis on road seismic damage when it is lack of pre-earthquake images. High-resolution pan image and airborne image are employed to study bridge seismic information extraction method.4. Feature optimal scheme and context feature of typical seismic secondary disasters are presented, typical seismic secondary disasters information extraction is accomplished using object-oriented change detection methodThe characteristics of multi-source remote sensing image of typical seismic secondary disasters, which include landslide, collapse, debris flow and landslide-dammed lake, are summarized. It is pointed that ground objects'spatial relationship features is the important judgment basis to recognize secondary seismic disasters. Consequently, reasoning rule was brought forward to recognize seismic secondary disasters. The procedures of seismic secondary disasters information extraction are illustrated using post-earthquake image only and pre- and post-earthquake images with object-oriented change detection method.5. A new threshold selection method for different seismic damage level is presented when using radar images'interferometric coherence change index.The methods of correlation analysis and interferometric coherence change index using radar image are analyzed. It is proved that correlation analysis method is a macro-assessment method for seismic disaster by experimental study on the selected 20 example areas in Wenchuan earthquake. A new threshold selection method for different seismic damage level is presented when using radar images'interferometric coherence change index. This method can overcome subjectivity of threshold selection. Seismic damage level map is draw using this method and validated by ground investigation. Moreover, it is proved that this threshold selection method is more rapid and efficient than ground investigation.6. The technique procedure of RS earthquake emergency response and rapid assessment was presented,several key technologies related to this procedure and its software implementation are analyzed.Distributed database system, RS seismic disaster information extraction and rapid seismic damage assessment system and web publishing system of remotely sensed imagery are integrated in the remote sensing earthquake emergency response software platform. Based on that platform, RS seismic disaster information is obtained rapidly about Wenchuan earthquake. The seismic intensity distribution map based on remotely sensed imagery is draw and validated that it is accordance to Wenchuan seismic intensity distribution map based on ground investigation. Consequently, the effectiveness of RS seismic intensity determination method is validated.