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