嫦娥一号卫星CCD立体相机月表图像镶嵌

Mosaic of Lunar Image From CCD Stereo Camera Onboard Chang'E-1 Orbitor

鉴于嫦娥一号CCD相机获取图像的特殊性,选用投影的方法,完成了Apollo12,Apollo14和Apollo15登月点区域的月表正视图像镶嵌.在分析圆柱投影表象的基础上,推导出了月球割35°Mercator投影公式.首先读取单轨数据的经纬度和灰度,进而根据四个角点的经纬度建立空图框,并根据分辨率、长度比与月球投影理论分别在纵向和横向上进行网格划分,实现图框的像元化.通过单轨图像和图框的坐标匹配完成灰度镶嵌,匹配误差控制在一个像元以内.对重叠区域的灰度值进行平滑处理,最终图像还原来完成月表图像的镶嵌.该方法有普遍适用性,可以用于其他轨道图像的镶嵌.

In view of the image particularity of stereo camera onboard Chang＇E-1 orbitor,the projection method was selected to complete the lunar nadir images mosaic of Apollo 12,Apollo 14 and Apollo 15 landing sites.Based on analyzing cylindrical projection,the coordinate formulae of lunar shearing 35°Mercator projection were obtained.Firstly,the latitudes,longitudes and DN values were read and written to files.A blank frame was established using the four vertices＇ latitudes and longitudes.Then grids were divided in vertical and horizontal directions,according to the resolution,length ratio and projection theory,realizing the frame＇s pixels.The DN mosaic was completed along with the coordinates matching,and the matching errors were controlled in less than one pixel.At the same time,the DN values were smoothed for the overlapped regions.Finally the DN values were restored to image,which was the mosaic image.The method has widespread use, and it can also be used for other tracks images mosaic.