三维图像建模在古地震探槽研究中的应用  

THE APPLICATION OF IMAGE-BASED MODELING IN PALEOEARTHQUAKE TRENCH STUDY

作　　者：高伟[1] 何宏林[1] 邹俊杰[1] 石峰[1] 

机构地区：[1]中国地震局地质研究所,活动构造与火山重点实验室,北京100029

出　　处：《地震地质》2017年第1期172-182,共11页Seismology and Geology

基　　金：中国地震局地震行业科研专项(201408023)资助

摘　　要：探槽揭露的地质构造信息十分珍贵,是正确认识断层活动性和古地震信息的关键资料,但是探槽本身无法长久妥善保存,因此完整精确地记录探槽揭露的地质构造信息一直受到人们的重视。传统的探槽记录方法主要有素描和照片拼接2种,但前者缺乏色彩信息且包含过多主观解释内容;后者在照片几何拼接过程中会出现接边、畸变等问题。文中以甘肃省天桥沟-黄羊川断裂的柳条河探槽为例,介绍1种完整记录探槽高精度的三维地质构造信息的技术方法和工作流程。该方法基于三维图像建模和正射镶嵌技术,首先在野外对清理好的探槽建立控制点或比例尺,用数码相机采集探槽所有剖面及周边微地貌照片,然后在室内用图像建模软件进行探槽的三维图像建模,最后生成探槽的三维图像模型及其剖面的正射镶嵌图。结果表明:探槽的三维图像建模既可以实现高分辨率正射照片镶嵌的自动化,又可以高效、低成本地获得高精度的探槽三维图像模型,不仅有利于探槽信息的存储,更可以直观地获取更多地质构造三维信息。The geological structure exposed by paleoearthquake trenches is the key material to the right cognition of fault activity and paleoearthquake. However, paleoearthquake trenching inevitably destroys active tectonic geomorphic evidence and trench exposures are usually difficult to reserve. The conventional process of recording the delicate geological information, manually constructing photomosaics by image-editing software, is time-consuming and produces undesirable artificial distortions. Herein, we explored the process of constructing trench orthophotomosaics and the 3D image model using the Image-based Modeling technology and applied it to the Liutiaohe trench across the Tianqiaogou-Huangyangchuan Fault, Gansu Province. Based on the 3D image modeling and orthophotomosaic, we firstly constructed the control points and scale bars on cleaned trench walls and collected photos of all sections of the trench with a digital camera in the field, and then reconstructed the 3D model of the trench through the Agisoft PhotoScan, an efficient image-based modeling software, and finally yielded the 3D image model of the trench and othophotomasaics of the trench exposures. The results show that the automated workflow can produce seamless, sub-millimeter-level high-resolution photomosaics more quickly, with precision in the centimeter range, and the 3D image model is of great help to identify strata and geological structures in trenches with much lower capital and labor costs and low expertise levels compared with LiDAR, meanwhile, the 3D archive benefits the share and communication and even allows future reinterpreting the site using new insights.

关 键 词：古地震探槽 基于图像建模 正射镶嵌 三维图像模型 

分 类 号：P315.2[天文地球—地震学]