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.
