The Richmond Virginian. (Richmond, Va.) 1910-1920, 1919-06-08

0AQuoUta made to the United states
BIOLOGICAL Survey department of the
interior. for information concerning
H. possibilities of Photographic sur
SW1ng from Airrianes or other air
sfDSt have recently become so numer-
- that II Ia deemed necessary TO
l1Uuo Q statement on this subject. For
tWo yearS the United States Geologi-
cAl survey, which prepares and pub
mnAeo more maps than any other or
eunixation In the world, has devoted
much time and labor 70 the study Of
problems TO BE- solved In photoaerial
surveying. The camera has long been
uoed In surveys on the ground. and the
geol0gicAl survey has been making
studies to determine the best methods
u using II In aerial work Before the
war the panoramic camera was en-
pl0yod BY the geological survey for
mapping in Alaska, and u had been
widely used for Photographic survey
ing In Canada and in Europa. Aerial
Photographic surveying involves no
new principles. yet 1t differs essentially
from Photographic surveying on the
9round. for the line of view from a
camera in a balloon or an asrplane Is
vertical. NOT horizontal A complete
statement Of the geological survey $
Investigations in photographic map
ring from the air viii later be pre-
pared for publication.
No a.rplane camera vet made IS
ADAPTED to every use and all such
cameras are subject to certain hmita-
iona IN aerial surveys cameras OF
different kinds will probably he re-
autred, the kind TO Re used depending
on the nature OF the country to De
mapped and On the character of the
map to b made. Some OF the cameras
now employed IN aerial photography
ere better adapted to use IN war
locating gun EN- placcm for exam
pie--thAn TO mapping. The angle Of
view included In singielens cameras
b small, and TO attain wider angie
muls1ple-iens cameras Of various types
have been made, both In Europe ana
in the United States. In such cameras
ono picture is taken on plate ar
nlm IN a horizontal position and two
or more pictures arc made in positions
inclined 10 the frst. nv means OF
rectifying camera the inclined pictures
are afterward transformed to the
ntare Of the other and the three are
com hined 70 produce an extreme
~ideangla view The geological sur
xev has designed and had made
threatens camera that gives an angle
cf view Of about 19a degree II a
fast lens with ali angle Of view as
-rea: az this could be constructed It
might yield pictures AZ serviceable a.
those made ny the fnultiple-lens
camera hut all wide angle lenses are
SLOW and IN extreme WIDE angle lenses
she marginal illumination is poor.
Hence the nultipie -ifns camera IL
well adapted 70 much If he work that
MAJ he done n aeriai surveying
Mosaic Mars" Not Accurate.
TIE principal object In an aerial
r1r.sT IN to obtain IN horizontal
ria or flm a picture Of the area
reiow the camera IF fhe area is Il
fszzre Gha picture ~ II taken
sr.,r a. airriane on such a plate is
tytse map hut no apparatus has ve.
Nrsr 90 iSed that WIFI maintain the
-late in Il truly horizontal position
~'en the a.rriane is in motion. and
ae tho e%rti1's surface is almost no.
Mare Tiane tho Photograph must he
rn-rt eted 10 obtain a mar free from
6tefn tioH The nearest approach 70
IN aerial nssr SC far made Is the so-
~alI i "a4os{ac man which is really
nni a snap Al All hut mereN 4 patch
= prk ~ plse. ograrhs, TIE pictures
fJfrWoeinr enes a mosaic 81, nv distor-
Sons. lue partly u the deviation n
~ riste frpr; he Horizontal position
pna partly ~ relief In tie surface
rf4ot crrarhed md these distortions
reracr she ~, lure useless for accu
rate mar construction Distorted
RI, ng ~ OF an ARA that rms sea-
vlously G1sl ped can ha aid d. VT
st.er neteotK Of points wt 70 poo!-
tsoa nr. k.own. and by d. Leiie
y errcrs duo - distcrt IN a n1tssie
~1av he constructed that will present
81 rood appearance For correcting
ard revising older maps by the add
s.ea Of culture. timber areas. nnM
roads ard similar features such
snosaics have distinct value. but they
are worth little as material for usf
in constructing new maps.
The most pressing need In aeria
aurves ing is that OF stahilizing the
ctFpIare camera ANY deviation ot
the plate from the horizontal posi-
tion produces A distorted picture o.
The area photographed. and devia-
ton greater than quarter Of n de
Gree will probably Introduce errors
larger than those aliowa BILE in a mo
tiern topographic map The trouble
RAY he overcome by sta hiiizinE 'hf
n.rplane camera itself or by stabiiiz
ir- reference point from which Il
will he possible 10 measure th'
amount and direction Of the tilt II
each picture and thus 10 make tbs
recessary corrections. The first solu
ton ~ the problem is the more Il
he desired. hut the second may b
easier Many sta bilizing devices hav.
heen proposed hut none have beer
entirely successful Most 81 then