A second question concerns the means and data generally available for 
the proper execution of these cost calculation tasks. Commercial enterprises 
are by necessity the most active in this field, but are obviously reluctant to 
reveal information which might hamper their competitive situation. Govern- 
ment agencies are not yet very economics-minded and often do not bother 
too much about detailed cost calculations. Furthermore the value of the 
examples of cost analyses and comparative evaluations of different procedures 
published is quite limited, particularly to other potential users, since insuffi- 
cient information is given concerning the basic cost standards applied, and 4 
about the qualitative and quantitative aspects of the specific factors influencing e e 
the production standards in the projects analysed. As a consequence, it be- 
comes virtually impossible to translate the given information into the specific 
situation and problems of another undertaking. 
Cost models are therefore required which represent, possibly in a simpli- 
fied manner, the functional relationship between the resulting costs of execu- 
ting various sub-processes, and all the relevant influencing factors. In order to 
be efficient with regard to the applications mentioned here, these cost models 
should fulfil the following important requirements: 
— the should be designed in a fairly standardised form in order to facilitate the 
comparative evaluation of methods and procedures by other organisations; 
— they should be versatile to the extent that optimal use can be made of them, 
even in circumstances quite different from those encountered in the past. 
They should thus be differentiated as much as possible, in order to allow of 
application to other and new situations; 
— finally, the cost models must be dynamic. They are continuously affected 
by changes in the basic cost standards and by changes in the production 
standards. They must therefore be updated periodically. © o 
The aim of this paper cannot be, and is not, to solve the problem and 
give ready made answers. What the author hopes to achieve, however, is: 
— to raise the interest of the photogrammetric community in this important 
problem; 
— to initiate the necessary R & D activity required to carry out the theoretical 
modelling of the functional relationship between product and cost; and 
finally