基于光谱精确采样的高光谱相机转扫成像几何校正

The Linear Hyperspectral Camera Rotating Scan Imaging Geometric Correction Based on the Precise Spectral Sampling

针对转扫式光谱成像系统在数据采集过程中,由于转台转速过快造成校正后的影像存在有数据漏洞,以及获取的原始影像数据存在有严重几何形变,影响影像上地物信息的分类与识别等问题,介绍了转扫式光谱成像系统的组成并给出数据采集一般过程,根据数据采集时单帧影像的覆盖范围和系统采集影像的速率等信息,在数据采集时对转台速度进行控制;结合影像获取时的起始与终止角度以及传感器距离前视点的距离等信息,详细推导了转扫式光谱成像空间定位模型,并对定位后影像进行格网划分和光谱重采样,给出了影像畸变校正的一般流程;鉴于影像空间定位后相邻帧间影像空间分辨率不一致,同时为保证获取最大的影像分辨率,采用最小空间采样间隔作为坐标定位后影像格网划分单元;考虑到新生成均匀格网与不均匀格网叠加进行光谱取值时,采用直接光谱采样可能造成的光谱混叠失真问题,提出了基于位置分布的光谱精确采样方法,以张家界老司城获取的高光谱影像数据为例进行畸变的校正,校正后影像上地物保持了原有的几何特征,验证了算法的正确性,同时抽取不同地物点的光谱数据进行相关系数计算,结果表明改进的光谱采样算法优于直接光谱采样,为同类产品的地面应用提供参考。

As the rotation speed of ground based hyperspectral imaging system is too fast in the image collection process, which exceeds the speed limitation, there is data missed in the rectified image, it shows as the black lines. At the same time, there is serious distortion in the collected raw images, which effects the feature information classification and identification. To solve these problems, in this paper, we introduce the each component of the ground based hyperspectral imaging system at first, and give the general process of data collection. The rotation speed is controlled in data collection process, according to the image cov- er area of each frame and the image collection speed of the ground based hyperspectral imaging system, And then the spatial ori- entation model is deduced in detail combining with the star scanning angle, stop scanning angle and the minimum distance be- tween the sensor and the scanned object etc. The oriented image is divided into grids and resampled with new spectral. The gen- eral flow of distortion image corrected is presented in this paper. Since the image spatial resolution is different between the adja- cent frames, and in order to keep the highest image resolution of corrected image, the minimum ground sampling distance is em- ployed as the grid unit to divide the geo-referenced image. Taking the spectral distortion into account caused by direct sampling method when the new uniform grids and the old uneven grids are superimposed to take the pixel value, the precise spectral sam- pling method based on the position distribution is proposed. The distortion image collected in Lao Si Cheng ruin which is in the Zhang Jiajie town Hunan province is corrected through the algorithm proposed on above. The features keep the original geomet- ric characteristics. It verifies the validity of the algorithm. And we extract the spectral of different features to compute the corre- lation coefficient. The results show that the improved spectral sampling method is better than the direct sampling method. It provides the reference for the similar product used on the ground.