•22- 
nel as well as faster methods, although lowering the accuracy standard. 
On the other hand the cost and time required for small or 
medium scale mapping of large areas, often imply a search for a more 
economical answer. '^his is the case in Mozambique where more than 50/ 
of the whole surface has not yet been mapped at 1/50.000. 
Nowadays several fields of development planning are ma 
king extensive use of the technique of photo interpretation, namely for 
Soils, Forestry, Geology, Prospection, Communications, Health, etc. 
The 1/250.000 reconnaissance map which, although rather good for the me 
thods and difficulties of the time, does not comply with the present 
requirements and needs. The same holds true for the non controlled mo- 
saios in the scale of the aerial photography (1/4O.OOO or 1/5O.OOO). 
In this connection it is believed that the first and most desirable 
step is a quick execution of semi-controlled mosaics of the areas not 
yet mapped at 1/50.000. The need is emphasised when publication of 
geological or soil maps at scales l/lOO.OOO to 1/250»000 is undelay 
able . 
For this purpose the use of the Airborne Profile Recorder 
for the scale control and altimétrie data and of the horizon camera 
or gyroscopes for tilt determination are indeed most recommended. 
This extra data will be also of the utmost importance to speed up 
and reduce the cost of the ensuing 1/50.000 photogrammetric maps. 
4.- The advantages of the present controlled mosaic over a r -tap at the 
same scale, as far as the immediate needs and possibilities were 
concerned, have already been emphasised. 
Acknowledgment 
It is the author's wish to express his appreciation to 
Mr. F. Castro Fontes, Chief Engineer of the M.F.P.Z., for the prompt 
supply of the general information referred to at the beginning of this 
paper and to Mr. F.H. Koch, photogeoloist of the P. Works Department, 
for his most valuable help in the translation. 
REFERENCES 
I. T.C. Delft - Planimetric or Radial Triangulation - Chapter XIII, 1957 
J. Visser - Cost of Aerial Surveys, Photogrammetria I96I-62, №.l 
K. Schwidefsky — An Outline of Photogrammetry (English Edition 1959) 
I.T.C. Delft - Restitution of Single Photographs - Chapter IX, 1957»