CONTROL OF A COMPARATOR BY PROPAGATION OF VARIANCE AND COVARIANCE

摘要

The photocoordinates measurements, as it is well known are made - by a comparator (stereo or mono). Images of the fiducial marks - appear on each photograph. They are defined and marked better than images of pass or control points. We can say that the images of - the fiducial marks, as they appear in two sucessive photos, are - located in the same relative positions. By comparing the lenght between fiducial marks in all sucessive pair of photos of the block, we can stimate the uncertainty of a single coordinate measurement by application of propagation law of variances and covariances. - So, it is possible a coarse control of the comparator by using as reference the uncertainty of a single coordinate measurement obtai ned from the usual measurements on the fiducial marks, as they are obtained in an aerotriangulation block. A numerical example is also given.