Journal of Geodesy and Geoinformation Science ›› 2024, Vol. 7 ›› Issue (3): 42-56.doi: 10.11947/j.JGGS.2024.0303

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A Multi-Baseline PolInSAR Forest Height Inversion Method Taking into Account the Model Ill-posed Problem

LIN Dongfang1(), ZHU Jianjun2(), LI Zhiwei2, FU Haiqiang2, LIANG Ji1, ZHOU Fangbin3, ZHANG Bing4   

  1. 1. Hunan Provincial Key Laboratory of Geo-Information Engineering in Surveying, Mapping and Remote Sensing, Hunan University of Science and Technology, Xiangtan 411201, China
    2. School of Geosciences and Info-Physics, Central South University, Changsha 410083, China
    3. Hunan International Scientific and Technological Innovation Cooperation Base of Advanced Construction and Maintenance Technology of Highway, Changsha University of Science & Technology, Changsha 410114, China
    4. School of Geomatics, Liaoning Technical University, Fuxin 123000, China
  • Published:2024-09-25 Online:2024-09-23
  • Contact: ZHU Jianjun, PhD, professor, majors in surveying adjustment and PolInSAR application. E-mail:zjj@csu.edu.cn.
  • About author:LIN Dongfang,PhD, associate professor, majors in surveying adjustment and PolInSAR data processing. E-mail:lindongfang223@163.com.
  • Supported by:
    National Natural Science Foundation of China(42104025);China Postdoctoral Science Foundation(2021M702509);Natural Resources Sciences and Technology Project of Hunan Province(2022-07);Surveying and Mapping Basic Research Foundation of Key Laboratory of Geospace Environment and Geodesy, Ministry of Education(20-01-04);Natural Science Foundation of Hunan Province(2024JJ5144);Open Fund of Hunan International Scientific and Technological Innovation Cooperation Base of Advanced Construction and Maintenance Technology of Highway (Changsha University of Science & Technology(kfj190805)

Abstract:

Affected by the insufficient information of single baseline observation data, the three-stage method assumes the Ground-to-Volume Ratio (GVR) to be zero so as to invert the vegetation height. However, this assumption introduces much biases into the parameter estimates which greatly limits the accuracy of the vegetation height inversion. Multi-baseline observation can provide redundant information and is helpful for the inversion of GVR. Nevertheless, the similar model parameter values in a multi-baseline model often lead to ill-posed problems and reduce the inversion accuracy of conventional algorithm. To this end, we propose a new step-by-step inversion method applied to the multi-baseline observations. Firstly, an adjustment inversion model is constructed by using multi-baseline volume scattering dominant polarization data, and the regularized estimates of model parameters are obtained by regularization method. Then, the reliable estimates of GVR are determined by the MSE (mean square error) analysis of each regularized parameter estimation. Secondly, the estimated GVR is used to extracts the pure volume coherence, and then the vegetation height parameter is inverted from the pure volume coherence by least squares estimation. The experimental results show that the new method can improve the vegetation height inversion result effectively. The inversion accuracy is improved by 26% with respect to the three-stage method and the conventional solution of multi-baseline. All of these have demonstrated the feasibility and effectiveness of the new method.

Key words: multi-baseline; vegetation height; GVR; PolInSAR; ill-posed problem