PHOTOGRAMMETRIC SURVEYS FOR NAUTICAL CHARTING 
USE OF COLOR AND INFRARED PHOTOGRAPHY 
by 
Captain L. W. Swanson 
Chief, Photogrammetry Division 
United States Coast and Geodetic Survey 
Using color aerial photography for chart making will 
probably seem a bit strange to the surveyor and downright 
queer to the mariner--but we are finding that it provides 
an "all-seeing" eye for the detection of detail and an ex- 
tremely valuable accessory for the maintenance of up-to- 
date nautical charts. 
The purpose of this paper is to briefly tell about the 
advantages of color for certain phases of chart making. 
However, in order to provide a background for my subject, 
I must digress & bit to tell you about one of our partic- 
ular, and perhaps rather unique, charting problems. 
One of the principal functions of the Coast and Geo- 
detic Survey is to provide nautical charts of the 2% mil- 
lion square miles of coastal waters of the United States 
and its possessions, and the Commonwealth of Puerto Rico. 
This requires the publication and maintenance of about 820 
individual charts. This is quite a sizable area but size 
alone is not the principal feature. 
We are favored with many bays and harbors and extensive 
intracoastal waterways--particularly along the Atlantic 
Coast, the Gulf of Mexico, and in Alaska. All in all, a 
shoreline totaling over 100,000 miles and thousands of 
miles of protected or intracoastal waterways that require 
the greater portion of the 16,000 fixed aids (lights and 
day beacons) and 24,000 buoys that are maintained for the 
mariner. As a consequence, over 80%, or about 670 of the 
820 charts are published at scales of 1:40,000 or larger 
for navigation in these more or less restricted intra- 
coastal waters: 
WHERE THE NAVIGATOR IS RELATIVELY CLOSE TO LAND. 
WHERE SHOALS ARE OFTEN EXTENSIVE AND THE CHANNELS 
INTRICATE.