1sly 
rocedure 
import- 
ogra- 
ent 
native 
after a 
s an 
ramme- 
any 
ed very 
ed es- 
oduct- 
profiles 
image 
element was. controlled by the respective height of: the 
profile point, and Lacmann suggested the use of a model 
of the terrain or to.use profiles constructed from an eas- 
ily carved material, Such as tar paper, for this purpose. 
It is interesting to note that Lacmann begins his 
article with the statement that "the majority of the photo- 
grammetrically produced maps so far were obtained by rec- 
tification methods" ..., implying that the new procedure 
will permit further extension of the rectification 
approach to hilly.terrain. 
As we know, over 30 years elapsed before these 
early ideas were put to practical use. 
1. Direct Projection Type Instruments. 
  
a. Equipment built by the U.S.A. Geological 
Survey and the Kelsh Instrument Division of 
Danko Arlington, Inc, U.S.A. 
These are the instruments derived from the 
"Orthophotoscope" developed by the U.S. Geological Survey 
of 1956 according to R.K. Bean. They consist of three 
projectors mounted over a projection table. All three 
projectors can be of the same type (Balplex), accommoda- 
ting aerial photographs reduced to half size. In another 
version, T-64 equipment, the central projector is the 
  
  
  
  
  
Fig.2 The geometry of the T-64 equipment