altitude, the atmospheric refraction and the topography. It is considered that horizon picture
tilts can be compared with tilt values obtained from relative orientation in strip triangulation
under proper weighting of these values to determine the potential of such auxiliary data for the
performance of aerial triangulation. Reference is made to : " Noggrannhetsundersôkning avHo-
rizontkameran Wild HC 1 ", by Pentti Kaasila, Institute of Photogrammetry, KTH, Stockholm
70. [6]).
Switzerland :
Due to a dense network of existing ground control in this country there is no immediate
application of aerial triangulation with auxiliary data. Experiments are being performed in con
nection with the Wild Company using auxiliary data provided by the Wild Statoscope and the ho
rizon camera Wild HC 1. For the measuring of the horizon pictures the stereomicroscope is
used ; however, also experiments with a microfilm read out instruments are presently in pro -
cess. Since these tests are not yet completed no further information can be given at this time.
For the future the design and use of gyrostabilized camera mounts are considered.
The Netherlands :
Due to a very dense network of available ground control in this country it is felt that
there is no need for the performance of aerial triangulation with auxiliary data. Nevertheless
it is expected that in the future some use will be made of statoscope and A. P. R. - data. Fur -
thermore, it is assumed that the subject : Aerial triangulation with auxiliary data, is also stu
died in the I. T.C. ; however, no particular information has been obtained from this institution.
U. S. A.
Headquarters Aeronautical Chart and Information Center, U. S. Air Force.
This agency has a continuing interest in the development and use of aerial triangulation
with auxiliary data but it is felt that no specific information can be made available at this time.
Corps of Engineers, U. S. Army, Army Map Service.
This agency uses electronic (Shoran) controlled photography to provide auxiliary data
for the establishment of horizontal photogrammetric control used for : 1 : 250, 000 scale map
ping. It is pointed out that this method has proved to be an economical mean of obtaining hori
zontal control over vast areas in a relatively short period of time where ground control is vir
tually nonexistent. - It is planned to use in the future more precise electronic horizontal con
trolled photography (Hiran and Shiran) and to obtain electronic vertical controlled photography
by APR which could be related to the electronic horizontal controlled photography. - To obtain
new horizontal ground control the instrument Shoran nadir coordinates x and y are determined
at the Wild Autograph or the Zeiss Steroplanigraph which requires additional instrument rea -
dings and computations performed on the electronic computer Honeywell - 800. Individual strip
triangulations (40 to 70 models, flown from 20, 000 to 30, 000 ft above ground with a 6 " wide
angle camera) are adjusted on the basis of the nadir coordinates using a least squares adjust
ment programmed at the Honeywell - 800 which transforms the aerial triangulation points to
UTM coordinates using the given UTM coordinates of the Shoran control stations. - Ground con
trol for the adjustment of Shoran controlled aerial triangulation (strip triangulation) are located
on or tied to existing I. and II. order triangulation stations or are established by airborne elec
tronic trilatération with controlling stations approximately 200 miles apart. - The accuracy of
such aerial triangulation was found sufficient for 1 : 250, 000 scale mapping requirements. - In
average two man hours instrument time is required per model, and one man hour per model for
the adjustment utilizing the electronic computer.
Coast and Geodetic Survey
In this agency triangulation with auxiliary data in general is not used. It is felt that
through free aero-triangulation with conformal adjustment greater accuracy can be obtained,
and this even for single strips, than with aerial triangulation with auxiliary data. - Currently
the use of solar directions obtained with a solar camera is evaluated. This camera designed by
the U. S. Army Ballistics Research Laboratory consists of two Wild RC-7 plate camera cones
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