TEST ON JOINT ADJUSTMENT OF GEODETIC AND PHOTOGRAMMETRIC DATA
Gianfranco Forlani, Luigi Mussio
Ist. di Topografia, Fotogrammetria e Geofisica (ITM) -
Politecnico di Milano
Milano, Italy
‘ABSTRACT
The program CALGE, of network adjustment for planimetric or altimetric
or planoaltimetric geodetic measurements, and block adjustment by
independent models or bundles for the aerial and terrestrial photogram
metry, and joint adjustment of geodetic and photogrammetric data, has
been implemented by the computing team of the ITM in the last two years.
Direct solution, i.e. the exact Cholesky factorization within the
profile of the normal matrix and the computation of suitably selected
elements of the inverse matrix, after the application of a reordering
algorithm of modified reverse CutHill, McKee type to minimize the
bandwidth and the profile, is performed.
The program works with excellent performance for real examples of
geodetic networks and photogrammetric blocks, of about 10^ equations
and 5,107 unknowns.-
Two tests on joint adjustment are performed: the first uses italian
data collected for a technical map, the second uses the data of the
joint adjustment Test of the Commission A OEEPE.
1. THE ITM PROGRAM CALGE
The computing team of the ITM has developed in the last two years à
new program on joint-adjustment of geodetic and photogrammetric data,
as suggested recently /1/, /9/. This program, the first and at present
the only one .in Italy, is also performed to CALculate GEnerally the
adjustment of every kinds of geodetic networks (levelling, triangulation,
transverses, etc.) and photogrammetric (aerial or terrestrial) blocks
by independent models and bundles.
Some details on the program CALGE are given in the rest of this para-
graph; more detailed information can be found in the references /10/,
/11/. The flow chart of the program CALGE is shown in figure l.l.
The tangent plane for the planimetry and the local sphere for the altim
etry are used as reference surfaces. À new program GLOBO (= globe) is
announced as available in thenext year, using as reference system the
ellipsoid, where the differences of level are corrected with the ortho
metric correction and for the geoid ondulation, whereas the azimuthal
and zenithal angles are corrected for the projection or the component
of the deflection of the vertical /14/, /4/. On the other hand, the
transformation from geodetic to map coordinates is a final problem,
that can be separated from the adjustment.
The program accepts, as data, real cases and simulated examples. The
input uses four files for the measurements and the preliminary coor=
dinates and parameters of the geodetic and photogrammetric data. The
same arrangement is necessary in the output to save the adjusted co-
ordinates and parameters and the residuals both with their standard
deviation. The preliminary coordinates and parameters should be a-
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