基于无人机贴近摄影测量的剖面数字露头系统研发及岩层面重构方法

Research of digital outcrop profile system and reconstruction method of rock surface based on unmanned aerial vehicle close photogrammetry

针对大坡度、大规模的露头剖面考察中识别范围不足,面貌不全、人工依赖大、精度差、数据共享低的状况,使用无人机贴近摄影测量技术摄取露头剖面影像,建立毫米级精度的全景三维模型,采用Web GIS技术,自主研发网络版数字露头平台,实现露头数据的共享。为重构某一局部岩层面,三维模型表面需建立一个贴面。数字地球引擎Cesium内置方法、边界面法建立贴面时,出现了贴面范围不准确、内部不连续的问题,提出一种在Web虚拟场景上充分利用空间场景几何特征与空间距离度量关系,自动判定岩层剖面特征点的新方法。特征点作为加密点在空间范围内构建三维Delaunay三角网,准确标定出某一岩层范围,实现了剖面岩层的重构。结果表明,该方法重构的岩层范围正确,内部连续,结果清晰,为地质资料知识库构建提供辅助手段与数据支撑。

A new approach is proposed to address the issues of insufficient identification range,incomplete appearance,poor accuracy,high artificial dependence,and low data sharing in the investigation of large-scale outcrop profiles of a large slope.UAV nap-of-the-object photography technology is used to capture outcrop profile images and a three-dimensional model is established with millimeter accuracy.Based on this,a network digital outcrop platform is developed using Web GIS technology to share the outcrop data.To reconstruct a local rock surface,a veneer should be built on the surface of the 3D model.There are some problems such as inaccurate veneer range and discontinuity veneer in the methods of Cesium built-in and boundary surface which are often used to build the veneer.This paper proposes a novel method to automatically determine the feature points of a rock profile in Web virtual scene by utilizing the relationship between geometric features of spatial scene and spatial distance measurement.These feature points are used as interpolation points to construct 3D Delaunay triangulation network to form a veneer on the surface of the 3D model,enabling the reconstruction of the rock profile in the Web virtual scene.The experiments show that the reconstructed rock range is correct,and the internal continuous results are clear.It effectively calibrates the strata range and provides auxiliary means and data support for the construction of geological data knowledge base.