点目标的机载SAR辐射定标实验精度分析

Accuracy of Airborne SAR Radiometric Calibration with Point Target

辐射定标的精度高低直接关系着后续定量遥感技术应用。鉴于辐射定标工作的重要性,该文利用积分法与峰值法提取点目标能量,计算定标常数,并通过TerraSAR-X和机载SAR数据分别进行定标实验。依照定标实验,分析了影响定标精度的主要因素。其中,定标设备方面,三角形角反射器相比四面角形角反射器定标结果稳定;定标算法方面,积分法比峰值法定标具有更高的稳定性,但也有可能对定标常数高估。实验结果表明,机载SAR定标虽然受到飞行平台稳定性的影响,但依然取得了较高稳定度的结果。

The accuracy of SAR radiometric calibration directly affects the study of quantitative remote sensing technology. Firstly,the peak method and integration method to extract target energy was introduced and the computational method for calibration constants was given.Then,the TerraSAR-X and airborne SAR test was carried out,the calibration accuracy was calculated and the reasons influencing the calibration accuracy were analysed.The experiments illustrate that the calibration result was effected by different corner reflectors.Compared with square trihedral corner reflector,the triangular trihedral corner reflector was more stable.The calibration result was also influenced by different methods.Though the integration method was more stable than the peak method,it was also possible to overvalue the calibration constant.The results show that although airborne SAR calibration was influenced by flight stability of the platform,it could achieve high calibration accuracy.