测绘学报

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基于多方向多源合成孔径雷达数据融合的假彩色正射影像制作

张继贤,魏钜杰,赵争,黄国满   

  1. 中国测绘科学研究院
  • 收稿日期:2010-11-18 修回日期:2011-02-25 出版日期:2011-06-25 发布日期:2011-06-25
  • 通讯作者: 张继贤

Color Orthophoto Map Generation Based on Multi-direction and Multi-polarization SAR Data Fusion

  1. 1.
    2. Chinese Academy of Surveying & Mapping
  • Received:2010-11-18 Revised:2011-02-25 Online:2011-06-25 Published:2011-06-25

摘要: 合成孔径雷达(SAR)为常年多阴雨、多云雾、多冰雪覆盖地区提供了一种有效的遥感对地观测手段。但对于中国西部等地形复杂区域,高山峡谷多、地势起伏大、地貌类型复杂,获取的SAR影像几何失真大,透视收缩、叠掩和阴影等现象严重,地形起伏引起的辐射畸变突出,严重制约了SAR测图的应用。针对复杂地形区域及SAR成像的固有特征,本文提出了一套基于多方向多源SAR数据融合方法与技术流程,并在自主软件“雷达测图工作站”的基础上开发了相应的软件模块,利用不同侧视方向、不同分辨率、不同极化的SAR影像数据,融合制作SAR假彩色正射影像:运用目标分解原理对多极化数据进行极化合成制作假彩色影像,在稀少控制条件下基于距离-多普勒模型实现对SAR影像的几何校正,并利用高精度DEM消除地形起伏引起的辐射差异,运用IHS变换法对同一侧视方向的高分辨率单极化和低分辨率多极化影像进行融合,最后,基于坡度坡向信息对多方向SAR影像正射影像中的叠掩、阴影区域进行信息补偿。本文采用横断山脉区域3米分辨率的TerraSAR-X单极化影像以及8米分辨率的RadarSAT-2全极化影像进行融合实验,制作了假彩色正射影像。试验表明,本文的方法是有效、实用的。目前,上述方法、技术流程和软件在“国家西部1:50000地形图空白测图工程”中已经得到了广泛应用。

Abstract: Synthetic aperture radar is an effective earth observation technique for areas with frequent cloud and mist cover, rain and snow perennially. But in some complex terrain areas, such as west China, there are a lot of mountains and canyons. Because of large terrain relief and complex geomorphic types, the SAR images acquired from these areas present serious geometric distortions. For example, foreshortening, layover and shadow, are usually extremely severe. The radiometric distortion induced by topographic relief is also strong. These factors limit the application of SAR mapping. In order to cope with these shortcomings, a new method and technical flow based on multi-direction and multi-polarization SAR data fusion is proposed according to complex terrain and inherent characteristics of SAR images. And corresponding software module is developed based on an independently developed software system-SAR mapping workstation. This method fuses SAR images acquired from different looking directions, with different resolutions and multi-polarization to make color orthophoto map. Firstly, it uses the target decomposition to make color images based on the multi-polarization SAR data. The color images are ortho-rectified using the range-doppler model with sparse ground control points. And the radiometric distortions induced by topography relief of the color images are eliminated using high-precision DEM. Then the SAR data of high resolution and single polarization is merged with a multi-polarized SAR data with lower resolution and acquired from the same direction based on the IHS transformation. Finally a fusion method is proposed based on slope and aspect to fuse data with opposite viewing directions in order to compensate the information in layover and shadow areas. A data fusion test is carried out using TerraSAR-X data with 3m resolution and single polarization and fully polarized RadarSAT-2 data with 8m resolution in Hengduan Mountain to make the color orthophoto map. The experiment result proves that this method is effective and practical. At present, the proposed method, technical flow and software module has been widely used in the 1:50000 Scale Topographic Mapping Project in West China.