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.
* Your assessment is very important for improving the work of artificial intelligence, which forms the content of this project