2 
II. SCOPE - DEFINITIONS. 
n. 1. Scope. 
The subject has so many aspects that even a limited treatment would be far beyond the scope 
of this paper. For this reason, the paper is limited to a review of those methods which are 
promising to increase survey economy. 
It deals with two main groups of functions: 
a. the execution of survey flight and navigation in such a way as to obtain good-quality 
aerial photography; 
b. the determination of camera station elements in survey flight as auxiliary data for 
aerial triangulation. 
II. 2. Definitions. 
Flight function. Final objective performed in flight by means of the relation and the cooperation 
of a number of elements. 
Element. Constituing part of a flight function. 
Example: If "flight altitude" is considered as a "function" which should be performed in 
flight or the values of which should be measured in flight, and if the flight altitude over mean 
sea level should be determined by means of barometric measurements, the "elements" 
barometric pressure at mean sea level at the flight area, 
air pressure lapse rate per unit of height, under actual flight conditions, 
and: static air pressure at flight height 
can be used to determine the momentary value of this altitude function. 
Performance. The goodness of a result, expressed as standard error or as maximum 
tolerable error in an appropriate unit. 
Examples: In this paper, performance of an altitude determination is expressed as standard 
error in meters height; performance of aerial survey navigation can be expressed in terms 
of lateral overlap tolerances. 
Cost. The multitude and variety of solutions to perform a certain function renders it 
impossible to represent their cost by a single figure. For many functions, two aspects are 
given: investment and operating cost. 
Investment. Investment is estimated for the acquisition of the necessary instrumentation; 
the estimate does not include aircraft cost, it does include aircraft modification and 
installation if these cost are appreciable. The amounts presented are estimates for the 
2r^EJ^^^S]litude_onl^. They do not refer to any specific make or model, and for this 
reason the names of manufacturers are intentionally omitted from this paper. 
Operational cost. Even more difficult is the presentation of operational cost as they are 
determined by investment, depreciation, operation and maintenance per year, personnel 
per year and per hour, incidental cost per hour use, etcetera. The estimates used in this 
paper are based on average use and are intended only to produce ajmeans_of comparison. 
Depending on quantity and intensity of use, operational cost may vary as much as a factor 10. 
Consequently, it is preferable to represent cost estimates in the form of graphs with 
logarithmic scale axes rather than in figures.