Alternative methods of determining the orientation of a stellar camera

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Virginia Polytechnic Institute and State University

Stellar photography has found use in the calibration of mapping cameras and in determining the orientation of the stellar cameras serving as attitude sensors, e.g. the lunar mapping cameras on the NASA Apollo 15, 16, and 17 missions. The equations used to relate the image measurements to the attitude of the camera are the collinearity equations of photogrammetry. These require initial approximations to the unknown attitude angles and the use of an iterative Gaussian correction algorithm. Simpler methods are described which do not require initial approximations to the unknown angles. Two of the methods are modifications of the Church method of space resection and the third is based on the mathematical formulation of a rotation transformation about a single axis. The methods require only two images for a solution. Modifications are given for using the methods with aerial and terrestrial photographs when the camera position is known and two or more control points are imaged on a photograph.