«16.
8,000 stereomodels. They demonstrate that a vertical accuracy
of approximately + 2 meters can be achieved in aerial triangu-
lation with statoscope of long strips in a routine production
with control only at the beginning and end of each strip.
5. CONCLUSIONS AND RECOMMENDATIONS
Recent developments in horizontal block adjustment permit
a drastic reduction in the density of horizontal ground control.
This achievement minimizes the importance of auxiliary instru-
ments furnishing horizontal information, but highlights the need
for airborne auxiliary data for determination of heights of
exposure stations, as well as of the angular orientation elements
of the aerial photographs at the moment of exposure. In order to
achieve progress in vertical aerial triangulation comparable to
that reached in horizontal aerial triangulation, extensive use
must be made of airborne auxiliary instruments (4).
The simplest, least expensive but very effective instrument,
is the differential height indicator - statoscope. It is in-
dependent of terrain and does not require a special operator in
the aircraft. It permits ceriol triangulation of long strips
(20 to 25 models) and reduces by 1/3 the vertical ground control.
An aerial triangulation system employing statoscope for
determination of differences in height of exposure stations
and APR for establishing of elevations of ground points virtually
eliminates surveys on the ground and yields results suitable for
compilation of contours at 15 meter intervals.
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