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STEREOSCOPIC MAPPING WITH THE U.S. COAST AND GEODETIC 
SURVEY NINE-LENS CAMERA 
by 
William D. Harris. 
It is doubtful that the nine-lens camera would have been developed if so 
many difficulties had not been encountered in using single-lens cameras to 
make photogrammetric surveys of coastal areas. Much of the coastline of the 
United States and Alaska is so irregular that single-lens photographs will not 
span across rivers and bays or from the mainland to offshore rocks and islands. 
The nine-lens camera has not only solved the problems involved in mapping 
coastal areas, it has proven to have many advantages over the single-lens 
camera in every type of mapping problem. 
The 210 mm normal angle lenses which are used in this camera give pho- 
tographic resolution and scale comparable with the normal angle lenses often 
used for large scale single-lens mapping. Resolution is further improved by less 
camera vibration possibly due to the massive rigid construction of the camera. 
The nine-lens camera has never been given a formal airborne resolving power 
test with the standard high contrast resolution targets but it is not uncommon 
to observe the low-contrast plow furrows in farmlands reproduced in the final 
print at a spacing of 18 to 20 lines per millimeter. The camera covers an angular 
field of 135 degrees which gives a base-height ratio of 1.6 with an overlap of 
65 per cent. The ground area coverage is nine times that of the wide-angle 6 
inch single-lens camera at the same flying height and sixteen times as much at 
the same scale. To illustrate the great coverage of the photograph, a 1: 30,000 
scale print images a square 17 miles of 27 kilometers on a side. The area covered 
is 289 square miles. — . 
The photograph is 35 inches square and has a principal distance of 8'/. 
inches. The maximum error of image position is 0.15 mm from that of a cor- 
rect perspective view. This precision in fitting the nine separate views into a 
single composite photograph is obtained by careful adjustment of the air 
camera and appropriate adjustments of the transforming printer to care for 
variations in dimensions of the film air negative. An airborne performance test 
is made each year, by photgraphing some eighty ground targets which have 
been located by first and second order triangulation and leveling. The elements 
of the transforming printer are then adjusted to make a correct photograph of 
the ground test area and the position of fiducial marks thus obtained is dupli- 
cated when making subsequent prints. 
Probably the most outstanding features of the nine-lens process are that it 
requires only about one third the usual amount of horizontal ground control 
and that the control may be established independent of the photographic plan. 
This means that the control can, if necessary, be established in advance of the 
aerial photography; that there are no special control position requirements, 
such as two points in the first model of each strip of photographs. It also means 
that usually all control can be established by triangulation using such objects 
as chimneys, steeples, water tanks, mountain peaks and pinnacle rocks. There 
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