BY W i ATTORNEY.
March 15, 1966
G. w. GODDARD
3,240,138
AERIAL CAMERA
Filed April 26, 1963
2 Sheets-Sheet l
COMPUTER
60/
T
56-‘ H
v
58
T
52
RADIO
ALTlMETER
DEISCRIMlNATéOR
'
LIGHT
DETECTOR
DISCRIMINATOR
I
GEORGE W GODDARD,
YNVENTOR.
\FIG.1
BY W
i ATTORNEY.
'
T.
March 15, 1966
G. w. GODDARD
3,240,138
AERIAL CAMERA
Filed April 26, 1963
82
2 Sheets-Sheet 2
u: I G . 2
GEORGE W GODDARQ
INVENTOR.
United States Patent 0 ” "ice
,
3,240,138
Patented Mar. 15, 1966
1
2
3,240,138
of its lens optical center. In most stereo strip cameras,
the lens are not set side by side, but instead are located
one ahead of the other.
Strip cameras are usually employed at low or medium
AERIAL CAMERA
George W. Goddard, Chevy Chase, Md., assignor to
Itek Corporation, a corporation of Delaware
Filed Apr. 26, 1963, Ser. No. 275,878
2 Claims. (Cl. 95-125)
altitudes at high airplane speeds. At high alti-tudtes, such
as 50,000 feet or higher, the short focal length lenses do
not provide useable scale resolution for target identi?ca
tion and hence is unsuited. To attain comparable scale
My invention relates to data processing systems and in
resolution, long focal length lenses must be employed with
particular to an improved stereoscopic photography
the disadvantage being that the use of matched long focal
10
system.
length
lenses increases the bulk and weight of the photo
The invention herein described has been found to be
graphic assemblage.
suitable for stereophotography, where there is relative
To overcome these disadvantages of the prior art sys
motion between the subject and the camera and is espe
tems, I have provided herewith an improved data process—
cially suited for making continuous aerial photographs
ing system comprising a single, long focal length lens and
exhibiting a true stereoscopic effect when viewed. It is
a ?lm mounted in the focal plane of the lens. The ?lm
within this latter context that I shall describe my invention
includes a ?rst emulsion layer responsive to only one com
although I do not wish to be so limited.
plementary color and a second emulsion layer superposed
The prior art aerial stereophotographic systems con
on a ?rst emulsion layer responsive only to a second
tinuously photographs the terrain over which the airplane
complementary color. The ?rst emulsion layer is ex
is flying and positions the images so that the resulting
posed at a ?rst angular projection when the lens is at
photograph has right and left handed pictures adapted to
the ?rst position and the second emulsion layer is ex
be brought into coincidence in an appropriate viewer to
posed at a second angular projection when the lens is at
give the effect of a three dimensional view of the terrain.
the second position. The superposed latent images thus
Another prior art system is to continuously photograph
produced in the ?lm provide the stereo~optic effect of a
the terrain in different angular projections and at slightly
three dimensional model of the object when the latent
different times. The images recorded at one angular
images are processed and viewed through two color
projection are arranged continuously on one side of the
spectacles having a ?rst lens responsive to the ?rst color
longitudinal axis of the ?lm while those images recorded
and a second lens responsive to the second color.
at a second angular projection are arranged continuously
on the other side. The resulting photograph also provides 30 It is, therefore, an object of my invention to provide
a stereoscopic View of the terrain. The same result is
attained if two ?lms are used, one to record one angular
projection and the second to record the second angular
projection.
A variation of the production of the stereoscopic effect
an improved data processing system for high altitude
aerial photography.
An other object of my invention is to provide an im
proved data processing system for high airplane velocity
aerial photography.
A further object of my invention is to provide an im
manifests itself in the case where both images are projected
proved data processing system for stereographic pho
one upon the other onto the same plane in complementary
tography.
»
colors, e.g. red and green. If this two-color image is
An
object
of
my
invention
is
to
provide
an
improved
viewed through two colors (one for each eye), e.g. red
and ‘green spectacles, an impression of a spatial image is 40 data processing system for multicolored stereo photog
produced. This system is called the anaglyph process.
Topographical relief maps made by this process consists
of a two color, zonally displaced print and the zonal dis
placement, varying according to the difference in altitude
of the camera above the object, appears as a plastic model. 45
One type of aerial photographic apparatus is the
shutterless strip camera that accomplishes continuous
aerial photography by transporting ?lm across a ?at
focal plane behind a variable width slit. Film velocity
raphy.
An important object of my invention is to provide an
improved data processing system for an aerial stereo
strip camera.
Another important object of my invention is to pro
vide an improved data processing system for a single
lens stereo strip camera.
A principal object of my invention is to provide an
improved data processing system that provides uniform
and exposure are controlled by a camera control system. 50 stereo effect regardless of changes in altitude.
Another principal object of my invention is to pro
vide an improved data processing system that provides
uniform exposure regardless of changes in illumination.
Yet another principal object of my invention is to pro
Asrin other types of aerial cameras, the ?lm is pulled
through the camera by means of a variable speed motor 55 vide an improved data processing system that is used
at high aircraft altitudes and velocities.
driving metering rollers and spooled up on a take-up
The features of my invention, which I believe to be
spool. The ‘?lm runs through the camera steadily, at a
novel, are set forth with particularity in the appended
rate selected by the camera control system and is capable
claims. My invention itself, however, both as to its
of photographing at great image motion speeds.
organization and methods of operation, together with
60
Strip cameras usually utilize two matched, short focal
further objects and advantages thereof, may be best un
length lenses to provide the same scale image for stereo
derstood by reference to the following description, taken
viewing but, to obtain the stereo effect, the image must
in conjunction with the accomapnying drawings in which:
be photographed from two slightly different positions.
FIG. 1 is a schematic block diagram of a data process
The exposure is controlled (in the camera) by adjusting
the width of the slit and the ?lm velocity across the slit
as the focal plane modi?es or effects the exposure value.
These two views are obtained in the stereo strip camera
by locating the slits at different points in the focal plane of 65 ing system embodying certain principles of my invention;
and
either lens so that an object is ?rst photographed through
FIG. 2 is a schematic diagram of the data processing
one slit and lens combination and a fraction of a second
system
of FIG. 1 at a later instant in time.
or seconds later through the second slit and lens combina
In FIG. 1 the arrow 10 indicates the direction of ?ight
tion of the same camera. Since, due to the forward flight
of the camera, the image moves from the forward part 70 of the aircraft and also the direction of ?lm travel. The
shutterless strip camera of the data processing system
of the ?eld to the back part of the ?eld, one slit is for
has its camera axis 44 orientated perpendicularly to the
ward of its lens optical center and the second slit is back
3,240,138
£0
direction of ?ight and includes a wide angle, single lens
34 of long focal length, as for example 36 inches. Film
11 is pulled continuously through the focal plane of lens
34 by a variable ?lm drive 68. The ?lm used is a super
posed combination of layers of emulsion 12 and 14,
deposited on a suitable base not shown.
While the emulsions will be described in terms of
being responsive only to certain color combinations, I
do not wish to be so limited since other combinations of
color responsive emulsions may ‘be used with equal
success.
Layer 12 may be peaked to respond to a relatively nar
row portion of the visible spectrum corresponding to
green light, while layer 14 may be peaked to respond to
a relatively narrow portion of the visible spectrum corre
sponding to blue light. It is well known in the photo
graphic art to place a glass ?lter or a gelatin ?lter be
tween the ?lm and the lens to provide primary color
separation. Since it is optional as to which is to be
used, I have not included the ?lters in the drawings for
purposes of clarity. Nor is any exegesis necessary since
those skilled in the art will recall many other appropriate
?lters to enhance primary color response in ?lm layers.
In a plane parallel to ?lm 11 are a pair of variable
4
the time of exposure. The output of altimeter 52 also
serves as an input to converter 56 for providing a signal
proportional to the altitude and which signal is suitable
for use in computer 60, wherein the signal is compared to
a reference signal previously inserted in computer 60.
This reference signal is a constant determined from the
characteristics of ?lm, lens terrain to be photographed,
weather conditions, altitude and velocity from optimum
data collection and is fed into the system initially, before
10 any pictures are taken. The output of computer 60 is an
error signal which is applied to slit drives 70 and 72 for
control of the respective slit widths as well as the dis
tances from the axis 44. If the altitude is increasing, slit
drive 72 will drive the center of slit 20a closer to camera
axis 44 while slit drive 70 will drive the center of slit 2%
proportionally closer to camera axis 44.
A second output of radio altimeter 52 is another signal
applied as an input to discriminator 62 to drive a printout
drive 66 to indicate on the edge of the ?lm the instanta
neous altitude at the moment of exposure. This mensura
tion information provides, during a subsequent viewing
of the picture on the ?lm, a means for accurately recreating
the conditions which existed at the time of exposure and
has particular utility for photo-interpretation purposes.
width slit apertures 20a and 20b. Slit 20a is formed by
At this point it is appropriate to con?rm, for future
a pair of slit blades 22a and 2212 while slit 20b is formed
usage, that lens 34 (in the absence of any of the slit
by a pair of slit blades 24a and 24b. The center of
forming device-22a, 22b, 24a, and 241)) would focus
slits 20a and 20b, respectively, are equidistant from
an image of the entire terrain 46 onto ?lm 11. However,
camera axis 44. The maximum distance between the
since the slits 20a and 2% are present, it should be noted
slits 20a and 20b is determined by the focal length of lens 30 that the slit position with respect to lens 34 determines
34, as for example, when lens 34 has a 36 inch focal
which portion (54 and/or 48) of the image appears on
length, the slit separation may be 18 inches to provide
?lm 11 while the slit width determines the intensity of the
correct interocular distance for stereo viewing. Both the
image portion that appears.
width of slits 20a and 20!) respectively, and their center
The amount of light transmitted to ?lm 11 is physically
distance from camera axis 44 is made variable. The
controlled by the width of slits 20a and 20b respectively.
width of slit 20a and its distance from camera axis 44
Thus, if the width is increased, exposure is increased, and,
is controlled by slit drive left 72 and the width of slit
conversely, if the width is decreased, exposure is de
20b and its distance from camera axis 44 is controlled
creased. To maintain exposure within narrow limits, I
by slit drive right 70. This control is shown by dashed
provide at each of slits 2% and 20b, a terrain light de
lines 74a and 74b respectively. When the width of slit 40 tector 54 for measuring illumination at the slit. The out
20a is to be decreased, slit blade 22a is driven in a
put of detector 54 is the input to converter 58 the output
direction of arrow 26a while slit blade 22b is simul
of which is a signal proportional to the luminous in
taneously driven an equal distance in the direction .~of
tensity and in a form suitable for use as an input to com
arrow 26b. Similarly, to decrease the width of slit 20b,
puter 60. In computer 60 the output from converter 58
slit blade 24a is driven in the direction of arrow 28a 45 is compared with a reference value similar to the one
while slit blade 24]) is simultaneously driven an equal
previously described to drive an error signal to be trans
distance in the direction of arrow 28b. To increase the
mitted to slit drives '70 and 72, respectively for increasing
width of slit 20a, slit blade 22a is driven in the direction of
or decreasing slit widths, as previously described. This
arrow 30a while slit blade 22b is simultaneously driven
maintains the exposure value within de?ned narrow limits.
an equal distance in the direction of arrow 3%. To
As is well known in the art of aerial photography, a
increase the width of slit 2%, slit blade 24a is driven
change in the ratio of velocity to altitude '(V/H) of the
in the direction of arrow 32a and slit blade 24b is simul
aircraft not only effects the exposure but also the rate of
taneously driven an equal distance in the direction of
image scanning across the ?lm. That is, the relative image
arrow 32b. To decrease the distance of the center of
velocity varies with changes in aircraft velocity and alti
slit 20a from the camera axis 44, slit blades 22a and 55 tude to cause image blur. To overcome this problem,
2211 are both driven, in unison, in the direction of arrow
?lm 11 is driven at a changing rate of speed to prevent
38a while slit blades 24a and 24b are both driven, in
image blur, and as is well known in this art, also provides
unison, in the direction of arrow 38b. To increase the
image motion compensation ?lm velocity. In my data
distance between the camera axis and the center of slit
processing system the output of converter 58 is compared
20a and 20b, slit blades 22a and 22b, respectively, are
with the reference of computer 60 to provide a control
both driven, in unison, in the direction of arrow 42a while
signal to discriminator 64 which in turn regulates ?lm
slit blades 24a and 2417, respectively are both driven, in
drive 68 to transport ?lm 11 at a velocity which compen
unison, in the direction of arrow 42b.
sates for image motion.
This facility for changing slit width and slit distance
At any instant in time slits 20a and 20b each have an
about the camera axis provides the necessary high altitude 65 instantaneous width while the distance between the cen
stereo-optic control for Obtaining maximum data read
ters of slits 20a and 20b are equidistant about camera
out. The degree of stereo-optic control is proportional
axis 44. This combination determines which portions of
to the instantaneous altitude and toward this end, I pro
terrain 46 appears on ?lm 11. Thus, the width of slit
vide a radio altimeter 52 for measuring the instantaneous
20a dictates that projection 50 of terrain 46 will be imaged
altitude of the aircraft above the intersection of camera 70 on ?lm 11. The limits of projection 50 are de?ned by rays
axis 44 and terrain 46.
40a and 40b. Similarly, the width of slit 20b dictates
An altimeter 52, preferably a radio altimeter as shown,
that projection 48 of terrain 46 will be imaged on ?lm 11.
emits a high frequency signal along a path shown as a
The limits or projection 48 are de?ned by rays 36a and
dotted line 86a and receives an echo along the path 86b
36b. Projection 50 is imaged on ?lm 11 at layer 12 in
to determine the instantaneous altitude of the aircraft at
the area 16 while projection 48 is imaged at layer 14 in
3,240,138
6
5
predetermined velocity, an incremental area of the
the area 18. Thus, we have both an aft looking image
other of said layers that is aligned with said incre
mental area of said ?rst layer to said portion of said
scene along said rearward looking projection axis,
to produce two superposed, aligned images of said
scene, which when later processed and viewed, yields
a stereoscopic picture of said scene;
of projection 50 and a forward looking image of projection
48 in ?lm 11.
Referring now to FIG. 2, there is shown the data proc
essing system of FIG. 1 at a later instant in time. When
reading FIG. 2, it is to be remembered that all the func
tional groups of FIG. 1 are present in FIG. 2, but have
been omitted merely to simplify the drawing. As pre
viously noted, with reference to FIG. 1, the slit width, the
means for measuring the total luminous flux passing
through at least one of said slits;
distance of the slit centers from camera axis 44, and the 10
?lm velocity are altered in response to error signals gen
means comparing said total luminous ?ux with a pre
erated by computer 60. Thus, in FIG. 2, lens 34 now
images an aft looking image of projection 48 on ?lm 11
while simultaneously imaging a forward looking image of
projection 82. The aft looking image of projection 48 15
is in layer 14 at area 18a superposed on area 18 and the
forward looking image of projection 82 is in layer 12 at
determined value to provide an indication propor
tional to the difference between said predetermined
value and said total luminous ?ux; and
means responsive to said indication to vary the width
of said ?rst slit and said second slit to maintain the
total exposure substantially constant.
2. An aerial strip camera for producing a stereoscopic
picture of a scene, said camera mounted in a vehicle for
area 80.
transporting said camera over said scene in a predeter
The data processing system thus records one angular
projection of an object in one complementary color in 20 mined direction, said camera comprising:
a single, wide angle of view, long focal length camera
one layer of ?lm 11 and a second angular projection of
objective lens system, said lens system de?ning a focal
the same object in a second complementary col-or in a
plane and a camera axis of symmetry passing through
second layer superposed on the ?rst layer to provide a
the projection center of said lens system substantially
latent image which, after processing is a colored, stereo
perpendicular to said focal plane in the plane of said
photograph of the terrain when viewed in a stereo viewer
predetermined direction;
equipped with one lens transmitting only the second color
a source of ?lm having a base, a ?rst emulsion layer
for the other eye of the viewer. The stereo effect is uni
disposed on said base sensitive to substantially only
form within narrow limits because the data processing
a ?rst complementary color, and a second emulsion
system provides automatic control in response to changes
layer disposed on said ?rst emulsion layer sensitive to
in altitude. Data readout is of an optimum quality be
substantially only a second complementary color,
cause the data processing system provides automatic con
said source including means for disposing said ?lm
trol in response to changes in illumination.
to receive light projected by said lens system;
While I have described what is presently considered a
a ?rst and a second elongated aperture slit each dis
preferred embodiment of my invention, it will be obvious
posed substantially in said focal plane, said slits hav
to those skilled in the art that various changes and modi? 35
ing parallel, elongated axis transverse to said prede
cations may be made therein without departing from the
termined direction and symmetrical about said cam
inventive concept, and it is aimed in the appended claims
era axis such that said ?rst slit is aft of said camera
to cover all such changes and modi?cations as fall within
the true spirit and scope of my invention.
40
What I claim is:
1. An aerial strip camera for producing a stereoscopic
picture of a scene, said camera mounted in a vehicle for
transporting said camera over said scene in a predeter
axis to de?ne a forward looking projection axis
through said projection center and said second slit
is forward of said camera axis to de?ne a rearward
looking projection axis through said projection center;
means for transporting said ?lm at a predetermined
velocity past said ?rst slit to expose an incremental
area of one of said layers to a portion of said scene
mined direction, said camera comprising:
a single, wide angle of view, long focal length camera
‘objective lens system, said lens system de?ning a focal
plane and a camera axis of symmetry passing through
the projection center of said lens system substantially
perpendicular to said focal plane in the plane of said
along said forward looking projection axis and for
tranporting said incremental area past said second
slit to expose, at a time interval proportional to said
predetermined velocity, an incremental area of the
predetermined direction;
a source of ?lm having a base, a ?rst emulsion layer
disposed on said base sensitive to substantially only
a ?rst complementary color, and a second emulsion
layer disposed on said ?rst emulsion layer sensitive
to substantially only a second complementary color, 55
said source including means for disposing said ?lm
to receive light projected by said lens system;
a ?rst and a second elongated aperture slit each dis
posed substantially in said focal plane, said slits
having parallel, elongated axes transverse to said pre 60
determined direction and symmetrical about said
other of said layers that is aligned with said incre
mental area of said ?rst layer to said portion of said
scene along said rearward looking projection, to pro
duce two superposed, aligned images of said scene,
which when later processed and viewed, yields a
stereoscopic picture of said scene;
means for measuring the altitude of said camera to pro
duce an indication proportional to its altitude; and
means responsive to said indication for changing the
interocular distance between said ?rst slit and said
second slit to maintain the aerial stereoscopic per
spective substantially constant.
camera axis such that said ?rst slit is aft of said
camera axis to de?ne a forward looking projection
References Cited by the Examiner
UNITED STATES PATENTS
axis through said projection center 'and said second
slit is forward of said camera axis to de?ne a rear
65
ward looking projection axis through said projection
center;
means for transporting said ?lm at a predetermined
velocity past said ?rst slit to expose an incremental
area of one of said layers to a portion of said scene 70
along said forward looking projection axis and for
transporting said incremental area past said second
slit to expose, at _a time interval proportional to said
2,184,016
12/ 1939
Mihalyi ____________ __ 95-57
2,413,349
2,433,534
12/1946
12/1947
Hancock __________ __. 95-125
Sonne _____________ __ 95-—18
2,568,327
9/ 1951
Dudley ____________ __ 95-18
2,929,305
3,046,857
3,076,189
3/ 1950
7/1962
1/ 1963
Blackstone ________ __. 95—12.5
Kargl ____________ __ 95——12.5
Goddard _________ __ 95-12.5
JOHN M. HORAN, Primary Examiner.
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