Orthocorrection of Corona KH-1 Satellite Panoramic Images

The orthocorrection of the very first satellite images are challenging, because the experimental assembly of the camera and the satellite had vibrations and other mechanical disturbances that heavily distorted the satellite images.The first imaging satellite system was the US CORONA spy satellite system in the early 1960s. The satellites used rotating cameras, that shoot a series of long panoramic images perpendicular to the satellite orbit. The slight overlap of these scans helped to piece together a photomosaic of the Earth’s surface. Nowadays, after 60 years, these images are digitized (scanned) and can be downloaded in digital format via internet.The method, used for transforming these oblique, panoramic images taken from orbital height is called orthocorrection or orthorectification. The method uses the projective geometry equations for re-projecting the image content to Earth's surface, so for the accurate orthocorrection of the image, the exact position and orientation of the camera should be known.The acquisition method of the panoramic images is very special, because the camera is moving during the shooting, and different segments of the film are exposed in different time. In this case for the accurate orthocorrection of the image, the position and orientation of the camera is a function of time, and it should be calculated for each segment of the satellite image for the proper orthocorrection of the image. For the calculation of the camera position and orientation as a function of time, least squares estimation methods are used, using the coordinate data of Ground Control Points (GCPs).In this paper I present a method for orthocorrection of CORONA images. The images are distorted by the mechanical disturbances of the camera, and this distortion of the scanned images should be corrected before orthocorrection. I also present the method for calculating and correcting this distortion.Finally I present the orthocorrected satellite image and how the correction of the image distortion before the orthocorrection increases the accuracy of the orthorectified satellite image.