ESTIMATION OF RICE PADDY HEIGHT FROM SINGLE-POLARIZATION TANDEM-X DATA BY A MODIFIED POL- INSAR METHOD

摘要

In this paper, the height of paddy rice is measured by a modified Pol-InSAR technique with a Random Volume over Ground (RVoG) model. To measure the height of rice paddy by the means of Pol-InSAR from space-borne SAR data, multi-polarization data sets are principally required. Although RVoG model requires quad-pol or at least dual-pol data, the TanDEM-X (TDX) mission normally provides single-polarization data. To overcome this limitation, we utilized a reference Digital Elevation Model (DEM) to reduce the multi-polarization requirements. In addition, extremely long baselines and small temporal decorrelation are required to improve the measurement accuracy. In order to achieve this condition, specifically designed TDX science phase data were obtained and used, where baselines between TDX and TerraSAR-X (TSX) were maintained as a few kilometers during the data acquisition, and no temporal decorrelation occurs between the two synchronized bistatic TSX-TDX observations. To improve the accuracy of height estimation, a single height value was given to each paddy, assuming paddy is flat. Preliminary results of the measurement demonstrate a potential use of the long-baseline bistatic Pol-InSAR approach for rice paddy height measurement. The temporal variation patterns of rice paddy heights will be examined and discussed according to phenological cycle of rice in the near future.