near perspective from 
ind not necessarily by 
era window. In order 
pil conjugate relation 
nent devised by Prof. 
ptics” (Einführung In 
1res-121::t0 124 was 
all along with a simi- 
vith three simple con- 
| display represented 
Bear Mountain and 
Hudson River. It was 
Transverse Mercator 
e of 1:25,000 which 
Xh the relief and the 
iform square grid was 
face and on the bor- 
nodel: the borders of 
the same plane as the 
any respects this ter- 
1 of the rapidly grow- 
ary at the Army Map 
the majority of library 
AMS are at 1:250,000 
present, the main use 
or the forming of the 
e plastic relief maps 
military purposes. 
10Wn a portion of the 
the south in parallel 
The relief or vertical 
erated optically three 
izontal dimensions of 
scriptive reasons the 
of the terrain model 
s of the relief and the 
dimensions as repre- 
1p the picture at right 
ther, the horizontal x 
the photogrammetrist 
F the oblique photo- 
most readily to scal- 
asel board on the tele- 
hic plate is placed on 
ative 1s then projected 
negative in the exact 
posed. When aligning 
the negative, the model remains on the 
easel to check positioning of the nega- 
tive in the camera. It is well to remem- 
ber that the datum plane of the model 
and the projection plane are parallel. A 
very great advantage results in using a 
collimated beam of projected light, 
particularly when using the camera as 
a projector for the high oblique view 
prints, for the light remains at uniform 
intensity over the whole area of the 
print. 
The parallel oblique view allows the 
z axis of the relief model to be opti- Fig. 3. : 
cally exaggerated or reduced at will Orthographic Oblique Perspective. 
while the x and y axes remain unchanged. 
Thus, at zero degrees the view of the model is truly planimetric; at 45° the 
relief has all moved in a parallel direction exactly proportional to the height of 
each point above the river level (or the vertical scale is not exaggerated), and 
  
  
Fig. 4. Inverse-Central Perspective. 
at 75°57 the movement of the relief was exaggerated to four times the hori- 
zontal scale (see Fig. 5). When the easel containing the model is tipped in the 
collimated beam, the amount of relief exaggeration can be expressed simply as 
the tangent function of the angle of inclination from the vertical; the relief 
movement will occur along the direction on any desired set of parallel lines 
when these lines are projected from a collimated beam upon the model. 
The parallel oblique projection will be recognized as a system widely used 
by early European cartographers. Very often the 45? oblique seems to have