- 59 -
Charles THEURER
îrial triangulation
the advent of elec-
e the growth of ana-
sasurably. This con-
vard photogramme-
ictors in the data
;omatic Point Mar-
•ecise photographic
sreocomparator that
mages on each dia-
if one micron. Iden-
;o can be marked
1 s console, two com-
ts of air bearingta-
g system, and a
■ to operate the e -
~ viewing the photo-
)n will be discussed.
:ks
clearly indicates
mmental techniques
)duces some new
n equal all-around
rips, is advocated.
Cantilever Sub-
A full account of
ub-Block Relative
iccessive Relaxa -
wly developed si-
Photogrammetry of
All the efforts that
include : ( 1) aero -
Corporation of Kan-
* missiles and sa-
vey ; (6) applica -
-.and Management,
special forms, ma-
results.
Approaching the Ultimate in Precision Photogrammetry
The precision of photogrammetrically determined positions and elevations has been
emphasized in the Coast and Geodetic Survey for the past four years. Analytic aerotriangulation
has been used extensively for control extension on productive work. Monocular comparators and
medium size electronic computers, utilized exclusively for the past several years, have been
supplemented by stereoscopic comparators and large capacity computers.
The general procedures in the application of both of these systems, including person
nel training, instrument calibration, computational procedures, and analysis of results are
described. Comparisons are made on the relative accuracy and productivity of each system.
The same instruments and personnel engaged in analytic aerotriangulation are used
interchangeably in the satellite triangulation program. The development of techniques for mea
suring star plates and processing of data is described, indicating accuracy of results. Pro
blems that were overcome and proposed solutions for those that remain are discussed.
FINLANDE
R. A. HIRVONEN
General Formulas for the Analytical Treatment of the Problems of Photogrammetry
Both exact formulas and approximate formulas for the practical use are given. Fol
lowing problems are discussed. 1. The absolute orientation of a single photograph with three
control points (pyramid problem). 2. The absolute orientation of a strip of photographs when a
pair of relative control points is visible on three successive photographs. 3. Observational
equations for the adjustment of strip and block triangulations. 4. Natural system of three-di
mensional coordinates instead of a map projection with heights.
It is suggested that an international recommendation be formulated for the definition
of the three rotations of the camera, especially for the logical order of angles khi, omega, phi.
Unto KORHONEN
On the Azimuth Transfer Error of Aerial Triangulation Strips.
The azimut transfer error, or bend, of the aerial triangulation strips is discussed.
The author has carried out investigations in order to discover, what the exact cause for this
error is and whether a Global Correction of the error could be determined in advance. A total
of 90 strips consisting of c : a 2400 models over test areas have been computed and analyzed.
It is well known that there are many sources of errors influencing the result of the ae
rial triangulation, many of these error sources not yet being detected. In this investigation the
author only could make distinction between errors of picture, errors of the measuring instru
ment and the errors made by the operator. The errors of picture were investigated by measu
ring photographs taken in various directions. The errors of the instrument were investigated by
bridging in various directions. The errors of the operator were investigated by repeating the
bridging of the same strip under unchanged circumstances.
The investigation, which was for the main part made in the Photogrammetric Research
Laboratory of the National Research Council of Canada, has resulted in a preliminary conclu -
sion, that the main part of the azimuth transfer error is caused by the errors of picture. The
errors of good instruments and those made by experienced operators have proved to play minor
role. The investigation also indicates, that with very careful tests it is possible to determine a
Global Correction to be used in bridging for small-scale mapping.