(63)
EtENCH SOCIETY
at of Photogrammetry
of applications and of
try in their work:
'.) which specializes in
metry (6 plotting ma-
as established a branch
whose field of activity
dotting machines which
n double projection to
to use ordinary rectifi-
ors of the photograph
h limited fields of view
^rammetry successfully.
)M Type B Stereotopo-
te (M.R.U.), Its efforts
)f urban localities. The
chano-graphic methods
a gyroscopic device in-
arganization has charge
>f the French Union; a
most diverse latitudes,
; employed for the exe-
idrons placed under the
his group whose home
)f four bimotor planes,
aphic airplanes serviced
equipment used is corn-
125 and 150 mm focal
10 cameras 13X18 with
3 interchangeable cones — 11 cameras 19X19 cm f = 125 mm and 22 film SOM
cameras f = 125 mm with a useable format of 18X18 cm.)
The photographic coverage has been:
in 1949 745.000 km 2
in 1950 1.120.000 km 2
in 1951 950.000 km 2 "and 750 km 2
for the first half of 1952; in three and one-half years 3.565.0000 km 2 , almost 7
times the area of France and nearly half the area of the United States; this in
conditions sometimes very difficult. In Guiana, for example, photographs can
only be taken between the hours of six and eight in the morning.
Mapping.
The mapping offices have been combined in a building constructed specially
for this use. They contain: A mapping office for 1 : 20.000 scale, making the
sheets of the Carte de France composed of two rooms, each with 18 stereotopo-
graphes Poivilliers-SOM type B, each machine operated by one photogrammetrist
and one draftsman.
The average production is 140.000 hectares per month or 16.800 km 2 per
year; precision in heights 0.80 meters, horizontally 3 meters. The average scale
of the photographs used is about 1 : 25.000 to 1 : 30.000.
A mapping office for 1/40.000 scale making maps of North Africa, com
posed of a room containing 11 Stereotopographes Povilliers SOM type C used
by a single operator. Horizontal average precision 6 meters, vertical precision
plus or minus 1.80 meters, production 110.000 hectares per month or 13.200
km 2 per year.
A mapping office for 1/100.000 scale is equipped with 13 stereotopographes
Poivilliers-SOM type D used by one operator. Horizontal precision 10 meters,
vertical 5 meters. Production: mapping at 1/50.000—4.500 km 2 per month or
54.000 km 2 per year. Mapping at 1/100.000, flat regions, planimetry only with
levelling directly on the ground: 8.200 km 2 per month or 98.400 km 2 per year.
A mapping office for rapid surveys for the use of wartime trimetrogon
photographs, equipped with 4 special Masson d’Autume plotting machines per
mitting stereoscopic use of the oblique views rectified with the aid of a special
apparatus.
Control.
Control points are established on the ground for the maps of France.
For the maps of North Africa, air photo bridging calculated from mea
surements made on two Stereotopographes Poivillliers SOM type B are regularly
used. Distance between ground control points 20 kilometers; photo scale
1/40.000 to 1/50.000; precision in x, y, and z, 2 meters; areas 1.200 km 2 .
For maps on 1/100.000 graphic radial triangulation is used with barometric
leveling.
Research Studies.
In research, progress has been forced in methods of plotting and aerial
bridging with the principal object of increased achievement in both production
