The Section for Stereo . plotting has been mainly engaged in the programme of City_
mapping to the scale 1:2500; from 1.12.500 photography. Total area plotted: about 220.000
ha. Of the 199 cities ( excluding Teheran ) 109 have been plotted abroad: under contract
with Fairey Air Survey. The remainder has been plotted in Teheran by the N. C. C. and the
four private companies. Also the checking of the work done by the contractors is executed
by the Plotting Section of the N. C. C.
Further» tte air fields of Skiraz» Yazd and Teheran(7500 Fa) were mapped to a scale
L 2500» a mining project ( 6500 ha ) to a scale 1:5000» an irrigation — project: partly to
1:3000 ( 680 ha ) and partly to 1:6000 (560 ha») a tracé of a future railroad ( 62000 ha )
to 1: 10.000 while» moreover: parts of the greater Teheran _ area were mapped to scales
I:1250 and 1:2000 (300 and 9150 Ea respectively).
Apart from the big stereo — plotters) mapping is done from rectified photographs. This
concerns a (flat regiom viz.a cultivated plain at the Caspian Sea. Poto _ scale and map
scale» both are 1:20.000. The procedure essentially is ( monocular ) cooying from
the rectified photographs but stereoscopy (mirror—stereoscopes) is used to identify and interprete
the details to be plotted. At present ( March 60) 200 out of the 500 rectified photographs
have been restituted (1800 sq km). This cheap and quick method will also be applied on other
projects with level terrain.
Slotted Templet triangulation has been used on two large areas with 1000 and 1200
photographs respectively.
Spatial aerial triangulation has been executed in the Wild A8 (before the Wild A7 was
availlable ) and in the Wild A7. In the former case the French Bonneval method has been
applied successfully.
A special procedure was developed in the N. C. C. for large — scale rectification of
photographs based on slotted templet control. This method has been applied extensively with
very good results.
Besides controlled mosaics,’ a great number ( 387) of un_controlled mosaics to scales
varying between 1:3000 and 1:100.000, have been made.
<3.
