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Is50,000j 1:30,000, 1:20,000 and 1:10,000 varied to suit the demands of the areas
and the planned use of the photographs.
A photographic laboratory was established in Santiago. More than 250,000
prints were made to answer the requirements of the Project and to provide reprints
for various government and private agencies.
FIELD CONTROL
Field control was required both for the preparation of the detailed topo
graphic maps of the damaged cities and for the preparation of the photo mosaics
used for the base map of the entire area.
Prior to 1960 the Government of Chile, with the cooperation of the Inter-
.American Geodetic Survey, had established a system of triangulation throughout the
country and had run a first order level line generally paralleling the Pan
American Highway. It extends in a north-south direction throughout the Project
area. Since many of the monuments in the vicinity of damaged cities had been
disturbed by the earthquakes, it was decided to use a local horizontal and verti
cal datum in these areas with plans to tie to the basic county system to be re
established at a later date.
Sufficient horizontal and vertical photo-control was established for the
photographs covering each city to provide orientation in the Wild A-8 and the
Zeiss Stereoplanigraph C-8 used in the compilation of these topographic maps.
The 1:20,000 mosaics necessitated the extension of the existing triangulation
and the establishment of sufficient control throughout the project area to control
the photographs for the photo-mosaic preparation.
CITY TOPOGRAPHIC MAPPING
As recommended by the OAS Mission, seven cities were provided with topo
graphic maps at a scale of 1:2,000 showing one meter contours.
Since the topographic maps were badly needed for the planning and recon
struction of the damaged cities, this work was given highest priority. A total
of 260 square kilometers in area was mapped by a total of 204 map sheets. The
topographic mapping performed by the Project provided an invaluable aid in the
