13 
IV. CONCLUSIONS. 
IV. 1 Survey navigation functions. 
To obtain good navigational results in all normal cases of aerial survey, a basic methodological 
knowledge is of greater importance than the use of more sophisticated instrumentation. Invest 
ment in know-how by means of education is an economic necessity. 
Doppler navigation computer can assist materially and is economically justified in difficult cases. 
The heading reference is its weakest link. 
Inertial navigation for heading would produce good performance but standard survey navigation 
methods - in difficult cases in combination with doppler - can perform nearly the same task; 
in view of the high investment, therefore, the use of inertial navigation will not be economically 
justified. 
IV. 2 Camera station elements. 
IV. 2.1 Planimetry. 
Performance of electronic methods in their different modes is good for primary trilatération 
(line crossing) and for secondary control point determination in small and medium scale mapping. 
Limits are imposed by the high capital investment: one single use of the instrumentation is 
prohibitively expensive and thus the methods can be economical in the hands of the contracting 
companies. 
IV. 2. 2 Altitude. 
Absolute altitude can be established with sufficient accuracy for photo scale planning and 
execution, (m z ~ 2. ..4 m). 
High accuracy can be obtained in the measurement and recording of bz altitude differences by 
means of simple methods (m z ~l m). In view of the benifits to aerial triangulation, the use of 
these methods is highly economical. 
It should be possible to obtain terrain elevation information up to accuracy of approx. m z ~1 m. 
The rather high capital investment can be economically justified for certain mapping tasks. 
IV. 2. 3 Verticality attitude. 
The cost versus performance shows the general trend of regular increase with accuracy, with 
two exceptions: 
a. horizon camera information can be remarkable cheap for its performance under good 
conditions; it can also have great uncertainty under poor conditions. 
b. gyroscopes are economical for measurement and control of the medium accuracy range 
(m~20'... 30'). Efforts spent on gyros to obtain substantially higher accuracy are 
relatively expensive. *) 
*) This is valid irrespective of whether recording only is applied or whether a camera mounting 
also will be stabilized; it is valid for different types of gyros: vertical gyro, rate gyro or free 
gyro.