DETERMINATION OF THE GEOMETRICAL QUALITY OF COMPARATORS FOR IMAGE COORDINATE MEASUREMENTS
ARMY ENGINEER GEODESY INTELLIGENCE AND MAPPING RESEARCH AND DEVELOPMENT AGENCY FORT BELVOIR VA
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The development and practical application of test procedures are used to determine the geometrical quality of comparators for image coordinate measurement. The procedures are founded upon grid coordinate measurements under operational conditions. First the basic principles for the determination of the accuracy of the measurements have been treated under different assumptions concerning the number and the positions of the test points. The principles of the method of least squares have been applied throughout, for the determination of regular systematic errors of the measured data as well as for the estimation of a statistical value of the irregular errors and for the error propagation in functions of the basic observations. The derivations have been made for grids, the given coordinates of which can be regarded to be errorless and for grids where certain regular errors are assumed to be present in the given coordinates. The theoretical derivations have been used for testing a number of comparators of different types. Also some determinations of absolute scales have been performed. The lowest standard error of unit weight found in a comparator is of the order of magnitude 1 micron. Normal distribution tests of the residuals have been performed throughout.