Summarising, the accuracy achieved using 35 mm non-metric photography and 
an unsophisticated co-ordinate measuring device, proves that the method is simple, 
cost effective and efficient. Therefore it is perfectly commendable for the 
applications and purposes that were presented earlier on. 
5. Considerations for the photogrammetric evaluation of 35 mm negatives 
  
Analogue plotting from the 35 mm kite photography was also attempted. Enlarged 
diapositives were produced for the accommodation of the principal distance on the 
Officine Galileo Stereosimplex IIB. Unfortunately relative orientation was not 
possible, firstly, because of the small size of the diapositives and, secondly, 
because of the large omega and phi rotations (Table 4). Consequently, the use of 
& universal instrument, like the Wild A5, was considered. This would require 
further enlargement of the negatives, thus deteriorating substantially the photo- 
graphic definition. Moreover, the use of an expensive plotter would defeat the 
argument of cost effectiveness and simplicity of the whole procedure. As a result 
of these considerations analogue plotting from 35 mm negatives has been abandoned 
for the purposes of this exercise. It is believed, however, that there is some 
useful potential in 35 mm non-metric photography. The nature and coverage of kite 
photography strongly suggest that multistation adjustment (Granshaw, 1980) could 
provide & rigid and rigorous solution. The application of this method using 35 mm 
negatives needs further investigation. 
6. Critical evaluation of the system 
  
In the following the limitations and possible improvements for the kite 
photography system will be assessed. The whole procedure will be examined, from 
obtaining the photography to producing the final results. 
The kite is a mechanism very much dependent on the wind. In the case of kite 
photography fairly strong and especially steady winds are necessary. The direct 
relationship between wind speed and payload is shown in Table 2. Thus the main 
limitation on the applicability of the kite photography system is again the weather. 
Practical experience has shown that a steady breeze of 5 knots is a minimum re- 
quirement. Moreover, a suitable lau-nching site is also required and should be 
situated away from trees, high buildings or any other feature that would cause 
turbulent wind droughts. However, for 80% of the time in the Greater London area, 
consistently throughout the year, the wind speeds are favourable for kite photo- 
graphy. Of course, rainy periods should be taken into account, but they normally 
do not exceed LO% of the time in the Greater London area (Anon., 1976). This is 
another limitation to the kite system, as rain water upsets the porosity of the 
fabric on the Dunford kites and they lose their stability. 
Furthermore, three or four persons is the minimum required manpower for 
completing a project. Some way of communication should exist, especially in this 
case, where the navigator may be obliged to stand quite far away from the actual 
site. Another problem is the difficulty of exactly positioning the camera above 
a certain target. The use of a 35 mm non-metric camera with a cloth focal plane 
shutter combined with the camera platform movement, could cause unpredictable 
image distortion. This is avoided by the use of fast shutter speeds and by taking 
each exposure when the kite is hovering. Finally, the difficulty of orientation 
of the camera is another limitation, which becomes unimportant when analytical 
methods for processing the data are employed. 
The photogrammetric procedure that was suggested and tested proved to be 
simple, cost effective and within acceptable accuracy limits. Access to an 
electronic computer or a mini-computer is, of course, a presupposition. Summarising, 
the kite photography system is an efficient, simple, easily transportable and cost 
effective means of obtaining photographs from low altitudes. It is, however, 
sensitive in weak and variable winds or within confined areas. 
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