虚拟CCD线阵星载光学传感器内视场拼接

以基于虚拟CCD线阵的多CCD影像重成像算法作为内视场拼接的技术手段,在对由地形起伏引起的多CCD影像的拼接误差进行理论分析和推导的基础上,提出无需数字高程模型(DEM)的虚拟CCD线阵多CCD影像重成像算法;并提出使用基于严密成像几何模型的空间前方交会的方法直接评价影像拼接对摄影测量生产的精度影响。研究表明,在虚拟CCD"安装"位置与真实CCD位置偏差不大的情况下,使用成像区域的平均高程进行拼接即可满足几何无缝拼接的需求;而在虚拟CCD"安装"位置与真实位置的偏离超过限差的情况下,可以用航天飞机雷达地形测绘DEM(SRTM-DEM)等一定精度的DEM数据校正地形起伏引起的拼接误差。使用先进陆地观测卫星(ALOS)卫星全色遥感立体测绘仪(PRISM)传感器三线阵影像作为实验数据,对前视、下视和后视的多CCD影像分别进行拼接。对拼接线的判读结果表明,影像拼接效果良好。另外,分别对拼接前和拼接后的前视、后视影像选取同名点进行空间前方交会,拼接后影像的空间前方交会精度与拼接前影像的空间前方交会精度一致。本文方法,可以无需DEM进行ALOS PRISM的内视场拼接,并使得拼接后影像的立体测图精度无损;拼接误差分析方法也可以在航空相机影像拼接中推广。

Inner FOV stitching algorithm of spaceborne optical sensor based on the virtual CCD line

To obtain bigger swath width,most high-resolution linear push-broom imaging systems use a many CCD chip configuration instead of a single chip configuration.The CCD chips cannot be fixed linear in the focal plane.The question "how to stitch the images obtained by the CCD chips to a seamless single image?" becomes important in the processing of high-resolution satellite images(HRSI).In this paper,an algorithm of inner filed-of-view(FOV) stitching based on the virtual CCD line is shown.With the derivation of the infection to stitching precision caused by height precision,we found that if the virtual CCD is installed near the real CCD,the average height could be used for the stitching algorithm without a loss of precision;otherwise,precise DEM data will be needed.Data from the ALOS/PRISM sensor has been used as test data to verify the algorithm.Through the stitched forward,nadir,and backward images,no position mistakes can be found.A rigorous geometry model of the stitching images also has been made.Comparing the forward intersection results and the original images rigorous sensor model and the stitching images rigorous geometry model,the stitching images has the same orientation accuracy.The ALOS/PRISM images can be stitched without DEM by this method,and the precision of stereoscopic mapping is not being reduced.This method also can be used for combining images from digital aerial cameras.