Gimrada contributes to advanced mapping techniques
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Anyone planning to write a book titled "Mapping Made Easy unght sP^n
his wheels for a long time looking for a better source of basic knowledge than
the U.S. Army Corps of Engineers Geodesy, Intelligence and Mapping
Research and Development Agency, Fort Belvoir, Va.
Mapping methodology has been facilitated almost incredibly by scientific
advances in recent years, and Gimrada has figured prominently m the
Labor-saving, time-cutting, dollar-stretching techniques developed by
the Agency for military requirements are no less important to many mapping
and geodesy problems with which civilian scientists and engineers are
g Army emphasis in surveying and geodesy, as related to research, develop
ment, design and testing of systems, is focused on combat operations
military mapping, peacetime mapping on a worldwide basis, and satellite
tracking equipment for geodetic purposes.
One of the greatest breakthroughs in the R &D program for surveying
and geodesy in many years came with the development of indirect-measuring
equipment, such as the geodimeter, which uses light waves as the measuring
medium and the tellurometer, which uses radio waves.
Although both items were developed by foreign firms, Gimrada was first
to recognize the importance of these new techniques and to introduce the
equipment in this country. Through a cooperative R &D program with
the foreign manufacturers, improved equipment was developed.
The tellurometer and geodimeter employ the principle of propagating
microwaves or light, respectively, between two stations. Since electro-mag
netic propagation velocity is a constant, the time lapse is readily convertible
to range or distance.
This equipment can be used to (i) insert baselines where it would be ïm-
possible employing conventional taping methods(2) m trilateration where
all sides of a geometric figure are measured, and (3) to check adjusted tnan
gulation lines to determine any distortions that may have been introduced
Private users with unusual survey problems estimate time reductions of
about 30 percent in good terrain conditions and up to 200 percent m moun
tainous areas.
One state highway department, for example, reported a saving of 100 000
a year for just one of these new tools, plus an added advantage of a substan
tial increase in accuracy.
In many instances, 2nd order surveys can be run at lower cost than using
previous 3rd order methods, and, in many applications, these new methods
largely replace expensive triangulation and tape-tra verses.
In the inertial field, rapid advances in precision gyroscopes have provided
a new surveying tool. A large fieldsize gyro-azimuth theodolite was developed
and now is in the hands of troops to give an all-weather independent capa
bility for azimuth work.
The principle used is the dynamic characteristics of a precision gyroscope
in conjunction with earth rotation to provide a north reference for theodolite.
This instrument was the forerunner of a new development, now m progress,
for a portable, lightweight instrument of the same accuracy but which can
be produced in quantity for about one-third the cost
This lightweight gyro-azimuth theodolite should be of interest to land
management programs, mining, geologic exploration, tunnel work air lines
for calibration and checkout of aircraft navigation equipment in the
hangar (rather than inconvenience of special calibration area set-up
use) and where strong local magnetic attraction make the ordinary compass
useless.
