Fig. 1. 
Key to the signs 
A^ triangulation point 
© photo-control-point, 
geodetically determined 
+ vertical control-point 
geodetically determined 
photo-control-point, 
O photogrammetricall 
proroga y 
vertical control-point, 
+ photogrammetrically 
determined 
control-point, photo- 
o grammetrically deter- 
mined 
——— traverse line 
sample plot, studied, 
B described andappraised 
——- boundary line 
—7  watercourse 
of 
    
T O 
0 1 kilometre 
Some principles of planning airphotography, 
geodetic horizontal and vertical control, 
photo-control-points, signalizing and forest 
sample areas. 
LED AO