Design And Development Of Add-in About Offset River Profile Information Extraction Based On DEM

Earthquake is the most destructive geological disaster in the world, bring a huge threat to human’s life, causing huge economic losses to the society. Otherwise, earthquake has close contract with active fault. Active fault is the essential factor of the earthquake. And offset rivers are the important symbols of the active fault. And offset rivers can response the activity of the fault. Thus, from how to get the profile information of the offset rivers, we can develop a profile information extraction system add-in of offset rivers to get the profile information. It will simplify the means of getting profile information and improve the efficiency of studying. It will bring great contributions to the analysis of regularity of fault activity and the research of earthquake repetition rate.In this paper, it takes Wallace Creek of San Andreas fault in Carrizo plain in California of America as an example. Develop the add-in and get some achievements. The results are as follows:(1) Get LAS data by lidar and convert it to high resolution DEM image.(2) Develop an add-in of ArcGIS by ArcObjects and C#to get profile information of offset rivers. The add-in contains functions as follows:①Get cross profile lines automatically by equal interval, It means that users can get the equal interval according to the length of the offset river drawing by users and the amounts of cross profile lines to generate cross profile lines automatically. And it can present cross profile images.②Search the bottom of offset rivers automatically and generate trend lines of offset rivers. It means that the add-in can present the lowest point of each cross profile. Users can get exact trend lines through lowest points.③Get longitudinal profile lines throngh trend lines and it can present longitudinal profile images.(3) This profile information data got by the add-in will be compared and studied with the data information got by Shunji Ouchi and some other researchers through field measurements to prove the add-in’s accuracy and superiority. It will offer some help to the study of fault activity.The add-in will be simply inserted to the ArcMap and it can save profile images information. Users can analyse the offset distance of offset rivers easily and reduce workload in field measurements. Users only need to use lidar to get the image data in their study area, they can obtain the profile information data efficiently and accurately by this add-in. It will offer scientific basis for the study of fault activity.