On the nonlinear integral transform of an ocean wave spectrum into an along-track interferometric synthetic aperture radar image spectrum

We present a new nonlinear integral transform relating the ocean wave spectrum to the along-track interferometric synthetic aperture radar (AT-INSAR) image spectrum. The AT-INSAR, which is a synthetic aperture radar (SAR) employing two antennas displaced along the platform's flight direction, is considered to be a better instrument for imaging ocean waves than the SAR. This is because the AT-INSAR yields the phase spectrum and not only the amplitude spectrum as with the conventional SAR. While the SAR and AT-INSAR amplitude spectra depend strongly on the modulation of the normalized radar cross section (NRCS) by the long ocean waves, which is poorly known, the phase spectrum depends only weakly on this modulation. By measuring the phase difference between the signals received by both antennas, AT-INSAR measures the radial component of the orbital velocity associated with the ocean waves, which is related to the ocean wave height field by a well-known transfer function. The nonlinear integral transform derived in this paper differs from the one previously derived by Bao et al. [1999] by an additional term containing the derivative of the radial component of the orbital velocity associated with the long ocean waves. By carrying out numerical simulations, we show that, in general, this additional term cannot be neglected. Furthermore, we present two new quasi-linear approximations to the nonlinear integral transform relating the ocean wave spectrum to the AT-INSAR phase spectrum.

自治式导航实验载体视觉系统（基于边缘图象的线性特征抽取及HougH变换方法研究）

移动式机器人系统的一个重要课题是视觉导航系统的研制。为了通过环境正确导航，移动式机器人必须感知和理解其环境结构，这样就必须提取与景物相关的模型特征。本论文一方面对视觉系统中的关键技术－－线性特征抽取进行描述与实施，并将其成果应用在道路边界的检测上；另一方面对视觉系统中的另一重要技术－－Hough变换，从理论到实验进行了详细的推导和验证。论文包括两大部分：1、线性特征抽取和道路界检测（包括模拟系统和实时系统）2、Hough变换的发展及其方法研究（包括快速Hough变换的硬件实现方案和用Systolic阵列机Hough变换的模拟实验及其结果）目前，线性特征抽取和道路边界检测的实时系统，己装在自治式导航实验载体上，用于视觉辅助导航。