The systematic correction and weighting of analogue aerial triangulation observations and their use in strip and block adjustments
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Date
1965-09
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Ohio State University. Division of Geodetic Science
Abstract
The report describes in detail the developing of a complete electronic computer program for strip and block adjustments in X, Y and H coordinates which utilizes the basic analogue data output of strip triangulations. The program is specifically designed to accomodate long strips and large blocks. Discussions are made of the justification and desirability of utilizing the proposed modified analogue solution in meeting those types of problems that are sometimes difficult for the more rigorous analytical systems to solve, and which will provide an interim solution for the huge mapping photography output expected in the near future. The following are features which make this program procedure unique and different from the general analogue adjustments: a) The plate positions of model points are determined first. Next the corrections to the plate coordinates due to residual lens distortions, earth's curvature, atmospheric refraction and linear film shrinkage are analytically computed and applied. b) The residual Y- parallax is read at six or more points in each model and the resulting differential model corrections are applied. c ) Corrections due to imperfect model connections are computed and applied. d) Expected error at each model point due to inherent image point error in the plate and as compounded by the imperfect systematic correction computations is computed for x, Y and H. This and the expected error on the ground control itself are used as the basis for weighting the eventual strip adjustment observation data. e) Seven forms of the conformal adjustment functions are tested. The error propagation for each form is integrated in X, Y and H of each point in the strip. The version predicting the minimum expected error propagation is the form used. f) The back-transformation into mapping coordinates is conditioned so that all first-order ground control is held fixed. g) The AN/USQ-28 airborne control system under development by the U.S. Air Force is expected to successfully provide an electronic positioning system to eventually provide complete exterior orientation data of the taking camera. This program was specifically designed to accomodate the AN/USQ-28 system. h) The print out includes , in addition to the adjusted coordinates, the expected standard errors at all point coordinates, misclosure on control and some statistical analysis. The computer also prints out plots which represent the distribution of error in the block in X, Y and H. The studies also show that the "SCATRAN'' source language of The Ohio State University system (utilizing the IBM 7094) is easy to modify so as to isolate for study purposes the improvement effects resulting from each of the innovations proposed. The block used in developing the program consisted only of three strips. The data had considerable estimated and fictitious entries included within it because of the lack of triangulation performed specifically for the new scheme.
Description
[Prepared for] U.S. Army Engineer, Geodesy, Intelligence and Mapping Research and Development Agency, Fort Belvoir, Virginia: Contract No. DA-44-009-AMC-568(X), Department of the Army Project No. 4A011001B850, RF Project 1835