TM 5-6675-323-14
(b) For map generalization, place large-scale map on glass stage and
place small-scale map on table.
(2) Determine photographic and map lens power. Lowest power provides great-
est field of view; highest power provides greatest detail.
NOTE
P h o t o g r a p h and map must be at same relative scale in order to make accur-
ate cartographic corrections.
(a) Determine map scale and photograph scale.
Example:
200 Scale:
1 in. on map equals 200 ft of terrain.
1 in. = 1 mi:
1 in. on map equals 1 mi of
terrain.
RF 1:24,000: Reduction factor of map. 1 in. of
map equals 24,000 in of terrain.
(b) Determine reduction factor (RF) of both photograph and map.
E x a m p l e : 200 Scale = RF = 1/2400: 1 in. on map equals 2400 in.
of terrain (200 ft = 2400 in).
1 in. = 1 mi = RF= 1/63,360: 1 in. on map equals 63,360
in. of terrain. (1 mi =
5280 = 63,360 in.)
( c ) D e t e r m i n e m a t c h i n g s c a l e S . U s e RF of photograph as 1/P and
RF of map as 1/M.
T h e n the scale S can be expressed as photo-
graph reduction factor (P) over the map reduction factor (M).
S = 1/M Divided By 1/P or S = P/M
Example:
Photograph RF = 1 : 8 0 , 0 0 0 ; Map RF = 1:24,000.
T h u s P = 80,000;
M = 24,000; and
S = 80,000/24,000 = 3 . 3 .
( d ) Use the value of S to determine map l e n s
and
photograph
magnification:
S Value
Map Lens
Photoqraph Magnification
1-7
1X
1X-7X
2-14
1X
2X-14X
Example:
I f 3.3 is value of S, then map lens of 1X and
e i t h e r 1X-7X attachment lens or 2X-14X (without
a t t a c h m e n t lens) may be used.
8-20
