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考虑地形起伏的机载SAR测绘航线规划方法

肖友刚1,满香娜1,伍国华2,罗启章3   

  1. 1. 中南大学交通运输工程学院
    2. 中南大学,复杂系统智能决策研究中心
    3. 中南大学
  • 收稿日期:2022-10-20 修回日期:2023-02-06 出版日期:2023-02-10 发布日期:2023-02-10
  • 通讯作者: 罗启章
  • 基金资助:
    国家自然科学基金

path planning method for UAV-borne SAR considering terrain

  • Received:2022-10-20 Revised:2023-02-06 Online:2023-02-10 Published:2023-02-10

摘要: 合成孔径雷达(SAR)能够不受天气、时间影响地获取高分辨率图像,因此被广泛用于测绘、灾害监测、环境监测、资源侦察等领域。由于SAR是侧视成像,在复杂的地形中雷达波束会被障碍物遮挡从而形成叠掩和阴影,这样不仅会造成数据的缺失而且会加重后续对数据处理的工作负担。针对以上问题,在进行无人机航线规划时,通常要保证相邻航带的重叠率来减少叠掩和阴影对图像质量的影响。为了在减少重叠率的同时保证高质量的成像,本文研究了考虑地形起伏的SAR测绘航线规划问题,将旁向重叠度、覆盖率和叠掩阴影率作为评价指标,提出了基于模拟退火算法的机载SAR测绘航线规划方法,并展开仿真实验对提出的方法进行验证。实验结果表明,本文所提出的方法能够将航带的旁向重叠度均控制在设定值以内,并使覆盖率达到90%以上,航线数量相比于以平均高度面为基准设计航线的方法降低了31.21%,测区覆盖率相比于完全不考虑地形的航线设计方法提高了84.80%;相比于Greedy算法在几何形变率和冗余航线数量上分别降低了8.73%,减少了100%。

关键词: 区域覆盖, 航线设计, 测绘, 机载SAR, 模拟退火

Abstract: Synthetic aperture radar (SAR) can obtain high-resolution images regardless of the influence of weather and time, therefore it is widely used in mapping, disaster monitoring, environmental monitoring, resource reconnaissance, etc. Due to the side-view imaging of SAR, the radar beam will be blocked by obstacles in some complex terrains, resulting in layover and shadow. It will not only cause data missing but also aggravate the workload of subsequent data pro-cessing. For the above problems, it is usually necessary to ensure the overlap ratio of adjacent flight swaths to reduce the influence of layover and shadow on image quality when planning the path of the UAV-borne SAR. To reduce the overlap ratio while ensuring high-quality images, this paper studies the SAR mapping path planning problem consider-ing terrains. Taking lateral overlap ratio, coverage ratio, and overlap ratio as evaluation targets, a UAV-borne SAR mapping path planning method based on simulated annealing is proposed. Besides, simulation experiments are car-ried out to verify the proposed method. The experimental results show that the method proposed can control the lat-eral overlap ratio of flight swath within the set value, and make the coverage ratio reach more than 90%. The number of paths decreased by 31.21% compared with the method of designing path based on the average altitude plane, and the coverage ratio of test area increased by 84.8% compared with the path designing method without considering the terrain. Also, geometric deformation ratio and the number of redundant paths are reduced by 8.73% and 100% respectively compared with Greedy algorithm.

Key words: area coverage, path planning, surveying and mapping, UAV-borne SAR, simulated annealing