Research of Low‐altitude Photogrammetry Implementation Strategy of China's Ancient Circumvallation

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www.as‐se.org/ssms Studies in Surveying and Mapping Science (SSMS) Volume 2, 2014

Research of Low‐altitude Photogrammetry Implementation Strategy of China's Ancient Circumvallation Project of Surveying and Mapping of Ming Dynasty Circumvallation (Southern Wall Section) Yu Yan*1, Zhe Li2, Haoran Shao3 National Key Lab of Surveying Tech Research for Architectural Heritages, Architecture School Tian Jin University No.92, Weijin road, Nankai District, Tianjin, China. *1

yanyu900606@126.com; 2lee_uav@tju.edu.cn; 3734800735@qq.com

Abstract: Most of the existing ancient circumvallation in China today is in the natural environment and the environment has never been cleaned up. As the blockings caused by the vegetation on the circumvallation itself, the surrounding vegetations, the constructions and other surface features affect the terrestrial laser scanning and the low altitude photogrammetry, there are often incomplete three‐dimensional points cloud data. Therefore, in the prior period of conservation works, surveying and mapping are difficult to implement under this circumstance. In this paper, based on the surveying and mapping of ZhengDing Ming Circumvallation and some other ancient circumvallation in northern China, characteristics of Chinese northern ancient circumvallation are summarized in the terms of their structures and spatial arrangements as well as the distribution of natural obstacles, and section paradigm pictures protracted. On the basis of these pictures, distractors of surveying and mapping are classified and fine adjustments are made to each category in aspects such as multiple aerial baseline setting, Unmanned Aerial Vehicle(UAV) control and equipment selection, parameter adjustment, ground assistant work, and selection of season, time and weather. The purpose of such adjustments is to get the best possible integrated centimeter level point density surveying and mapping data of the circumvallation so that the goal of optimal application of the technique of UAV low‐altitude photogrammetry can be achieved. Ancient circumvallation is the largest stock and most widespread type of architectural heritage in China. At present the surveying and mapping equipment available mainly falls into three categories: terrestrial laser scanning, low altitude photogrammetry and LIDAR. In this project, through analysis of characteristics, and summing‐up of rules, optimization of operating method is achieved, high density, high integrity surveying and mapping data under the condition of low cost and high efficiency is obtained. The results of this experiment prove that low altitude photogrammetry is more suitable for the surveying and mapping requirements of China's ancient circumvallation at present. This paper also gives a brief introduction to the LIDAR’s stronger penetrability and makes predictions about the application conditions, the effect and the promotion speed of ancient circumvallation’s surveying and mapping. Keywords: Ancient circumvallation; Complex environment; UAV, Photogrammetry, Optimization

General Situation of Chinese Ancient Circumvallation Ancient circumvallation is the largest stock and most widespread type of architectural heritage in China. The circumvallation has a strong relationship with civilization development due to the preliminary function to provide protection and defense. As many dynasty‐changes (Through dynasties) accompanied by wars in China, a great amount of circumvallation has been built and remained. In the modern society, circumvallation gradually changes to the tourist attraction and the reflection of history, and becomes a part of Chinese culture. However, circumvallation faces serious protection problems because of the aging of its internal structure, especially the loss of the rammed earth.  Roots of plant growing on the wall destroy its structure and introduce water into the wall, giving rise to the problems such as inner vacancy and collapse.  Long‐term weathering makes earth lose its viscosity. Earth gradually flows away. The whole wall becomes

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