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Part 2.
The results of the experiment work Monti di Revóira 1958 — 1960.
Introduction.
At the International Congress of Photogrammetry 1956 in Stockholm the Commission IV of the ISP decided
to continue experiment works, embracing both fundamental and practical problems. The question was
further discussed at the Conference in Brussels on the 9th of May 1958, where also further decisions
were made.
The fundamental theoretical problems should be dealt with by the Sub-Commission IV: 4 and the fundamen-
tal practical problems among others by the Sub-Commission IV: 1. Both the Sub-Commissions should use
measuring data from the same photographs, instruments and participators.
1. The purpose of the experiment work should be to study the accuracy of photogrammetrically deter-
mined coordinates, X, Y, Z, of signalized points and distances between them. Wide-angle vertical photo-
graphs and normal angle convergent photographs on approximately the same picture scale should be used,
two models (A and B) from vertical photographs on plates (I), two models from vertical photographs on
film (II) and two models from convergent photographs on film (III). So it would be possible to study the
influence on accuracy of plate and film, of vertical and convergent photography but also of the measure-
ment from the one or the other model in the overlap between two adjacent models. Only first order stereo-
plotters should be used. A short serie was however also measured in a stereocomparator. Coordinate trans-
formation and error calculation should be performed in Stockholm with large automatic digital computers.
It could however be necessary to modify this program during the work.
2. A test-field was arranged in Monti di Revóira in Switzerland. It was organized by Eidg. Vermessungs-
direktion, Dr. Hans Hürry. Field work, geodetic surveying and computation were performed by Dipl. Ing.
A, Pastorelli in Lugano together with Ufficio cantonale del catasto, Director Solari.
2.1 The test field, about 1 200 meters in length and 900 meters in width, was situated in an altitude above
sea level between 700 meters and 1 050 meters. The mean inclination of terrain was about 40 °/0.
2.2 Groups of 2—3 passpoints (in one case 4) in every corner of the models were signalized with white sig-
nals 30/30 centimeters. Because of gross errors some of these points could not be used. The numbers of the
used signals of every model were indicated in the Tables 1: I—III and 12 S.
2.3 About 160 check points were signalized with white signals 20/20 centimeters. However only a limited
number of them were surveyed geodetically. For that reason and for the presence of gross errors only a
selection of them could be used. The numbers of the used checkpoints are indicated in the Tables 1: —IIT,
12 S and 12 T. In each of the six models a certain number of checkpoints were common for all partici-
pators. Beside that the used checkpoints varied from one participator to another.
2.4 The pass points and the check points finally included in the research were surveyed trigonometrically
from two separate base lines. Coordinates and heights were calculated twice for each base line. The expected
standard error of mean for each of X and Y was + 1,5 cm and for Z + 4 em.
2.5 The coordinates and heights of the pass points were sent to the participators at an early stage of the
work. The coordinates and heights of the checkpoints were kept secret by Dr. Härry until the 10th of Juli
1960. Then thev were sent to Mr. Lundgren and kept secret by him until all measuring results had arrived
from the participators.
3. Aerial photography was planned and performed with RC5a and RC7a by the Eidg. Vermessungsdirek-
tion in Switzerland and performed with 2xRMK by the Zeiss-Aerotopograph in Germany. The develop-
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