DE1295202B - Autonomous stereo mapping device - Google Patents

Description

1 2

The invention relates to an automatic stereo card augenblickli ^ hön direction, der.Fensterwanderung animal device for deriving information from one in the Γ direction. That through the wandering window Stereo image, with a raster limited to the scanning of a diff erent one, is thus scanned line by line, tial surface area of the stereo image for the purpose of where the individual lines run in the X direction. Derivation of video signals serving scanning 5 Are the pinhole diaphragms so close together that direction that allows a slight overlap of the one in the face across the entire image area and the differential surface field entering the pinhole with this field area with separate line scanners to generate just leaving takes place, so a momender takes place Samples video signals, and with on the videotane increasing the intensity of the through the disc signals appealing facilities that drop the height io on the photomultiplier lying below it of the scanned image area. instead of the light. On the other hand, if

As is known, a land surface allows the scanning holes to be a little further apart,

to determine their topographical properties so that there is no overlap, a short one

measured from the air. For this purpose, interruptions to the photomultiplier are canceled.

from the corresponding earth's surface photographs 15 given light signal, as the one scanning pinhole

made, grouped into stereo pairs and in special the field of view a little before the entry of the following

Evaluation devices, for example in Kelshauswerter, a pinhole leaves. In any case, this occurs

set, with the help of which the altitude of each during the so-called dead time at the end of each

Determine point of the mapped terrain and line scanning an undesired interruption

then a corresponding topographic map her- ao or an undesirable compensation process in the an

in which the individual contour lines multiply the light signal emitted by the photomultiplier.

are drawn. With the help of the Kelshauswerters let the balancing process, which at a certain

which often takes place in the aerial photographs not point in a line scan interval

Compensate for avoidable distortions. When operating, no relation to the useful video

of the conventional Kelshauswerters is a series of signals from the photomultiplier, thus interfering with the correction

of slides used, the lation process in pairs. ; ......

consists of about 60% overlapping aerial photographs. Also occur with other precision scanning devices Every pair of slides that make up a stereo image in the video signals always shows errors when can be generated, is in the projection device when scanning in the photomultiplier of the Kelshauswerters inserted and with the help of known, 30 incident scanning beams not continuously in the photos of existing surveying marks override each other, but either override each other oriented towards each other. This process will lob or be spaced apart. Called model orientation. For these modelories, an overlap then results includes determining the correct spatial increase in the emitted light signal while borrowed relationship of the slides as well as setting 35 in the other case an interruption of the transmitted of the light signal present between two slides occurs. It is the object of the invention Angle. In this way, the position of the aircraft, the errors contained in the video signals reproduce at the time of aerial photography. and eliminate malfunctions. This is done inventively Model scale can be achieved by changing the according to the fact that the video signals dead time interval of the projectors. A 40 compensators are supplied which have the effect A small test area is then projected in the field of the stereo image that occurs in the video signals due to dead times arranged so that they eliminate the interference.

perceptible increase in a special image point and thus a measure of the height of each interruption or reinforcement of the of the terrain corresponding to the picture. The 45 photomultipliers emitted light signals on the Test area is now cut off to a given height value at the end of each scanned line. One of the hired and then over the projected stereo image-like dead time compensator is used in an advantageous manner field in order to thereby the contour line for this way also to maintain a signal level-height value to be determined. 'keep that of the average video signal-es is known that the test surface depends on the 50 precision scanning level, which over a certain, pre-device, For example, a Nipkow disk, was developed for a passed line scan area, turn that a rotating, disk-shaped so that a smooth transition from the one row body which is possible with a series of spiral scanning to the next. shaped perforated diaphragms are provided around the subject of the invention explanatory Ausfühseinen Run scope. While the Nipkow- 55 examples are in the drawing to which the disk in a Cartesian coordinate system refers to the following description, shown schematically, it rotates around its axis and thus feels posed.

the growth area of the stereo image within its F i g. 1 is an elevation of the major parts of a

Field of view on the basis of a line-modified Kelshauswerters from the front;

dismantling. For this purpose is located near 60 F i g. 2 is a plan view of the modified,

on the Nipkow disk a plate with a small, in Fi g. 1 shown Kelshauswerter and shows the Art

the window delimiting the field of view, so that the way of crossing the scanning mechanism;

individual perforated diaphragms of the Nipkow disk the F i g. 3 is a section through an optically evaluated

Line scanning in a specific raster by the stereo model developed in FIG. 1;

which is limited by this window. Will 65 F i g. 4 is a sketch showing part of a

this window is placed above the stereo model, so it represents certain orthophoto;

run through the individual apertured diaphragms. Fig. 5 is a sketch showing part of a

ned scan lines are essentially perpendicular to the correct slope shading map as they represent

according to the orthophoto of FIG. 4 manufactured can be;

F i g. Fig. 6 is a plan view showing the scanner used in the mechanics of Fig. 1; .

Figure 7 is a section through the scanner of Figure 6 taken along line 7-7; '

F i g. 8 is a section through the scanner of FIG. 6 along line 8-8;

F i g. 9 is a view of a Nipkow disk as used in the scanner of FIG. 6 is used;

Fi g. 10 is a simplified block diagram of the system of the present invention including the one in FIG Fig. 1 shown evaluator;

Fig. 11 is shown in schematic form to illustrate the sensing process to demonstrate for the increment error in the arrangement of FIG. 1;

F i g. 12 depicts waveforms representing the various correspond to the elevations shown in FIG. 10;

Fig. 13 is a block diagram showing an altitude error generator circuit represents; this can be included in the Z-axis control portion of the arrangement of FIG be;

F i g. 14 is a block diagram of a particular flip-flop generator circuit used as part of the Tilt control part of the arrangement of FIG. 10 can be used;

F i g. 15 is a schematic diagram of a particular correlator circuit suitable for use in the Arrangements of Figures 13 and 14 is suitable;

16 is a circuit diagram of a dead time compensator circuit; which can be used in the arrangement of Figure 10;

Fig. 17 is a block diagram used in greater detail Fig. 10 details the control part for the scanner carriage of the arrangement shown in Fig. 10;

F i g. 18 is a block diagram showing in greater detail the control parts for the Z-axis and Shows tilting of the arrangement of Fig. 10;

FIG. 19 is a block diagram showing details of the signal selection part of the arrangement of FIG represents;

F i g. 20 is a block diagram showing the recording part the arrangement of the F i g. 10 shows in more detail.

. In the arrangement shown in FIGS. 1 or 2 in plan or ground plan is a Kelshauswerter 110 in the modification for operation in the system to be described. The modified one Kelshauswerter 110 basically contains two light sources 112, two optical imaging mechanisms 113 with lenses 114, two slides 115 and 116, which are in the mechanisms 113, a scanner 118 and a base or bed 120 on which the entire device is built. Support members 127 of the Frames are indicated generally and can take any shape. The one on a scanner cart 119 suspended scanner 118 is arranged so that it can be viewed in three dimensions by means of a Af-axis guide rail 124 and a corresponding one Track 126, a Y-axis guide rail 130 and a corresponding track 132 and Z-axis guide rails 137 can move. This is to be understood in such a way that the Y-axis in FIG. 1 as rectangular to the plane of the drawing, on the other hand the X-axis as horizontal and the Z-axis as vertical in the Are to be seen lying on the drawing plane. Suitable support arms 122 for the light sources 112 are through shown in dashed lines indicating the approximate shape of the arms 122. These arms, slowly with matching handlebar loaders 128 and 129 the scanner 118 mechanically with the light sources 112, thus causing the various mechanical parts, move so that light is continuously directed at the scanner 118 when the latter measures his way through. Details of the scanner 118 are shown in FIGS. 6, 7 and 8 can be seen.

to When operating the modified Kelshauswerter of FIG. 1 and 2 become two slides 115 and 116, which correspond to the aerial photographs taken along the flight path of an aircraft, so inserted, that a suitable stereoscopic image or model within

* 5 of the area of the pickup 118 arises. The movement of the scanner along its in F i g. 2 indicated, automatically swept scanning pattern is then initiated, so that hereby the scanner 118 moves along the lines (along the Y-axis), the

ao be perpendicular to the airline; then follows a step over a preselected space in Direction of the flight line (along the ^ AT axis) always when the limit of the Y-crossing is reached. This process continues until the entire

he area of the stereo image is covered. The described Movement is made by the Y-axis drive spindle 133, which is driven by the Y-axis motor 134, and controlled by the AT-axis drive spindle 135, which are driven by the X-axis stepper motor 136 will. While the scanner 118 moves in the horizontal plane in the manner described, he can also move vertically along the Z-axis in order to follow a profile of the stereo image. The scanner 118 includes a Nipkow disk 140 and two photovoltaic tubes 150 and 151, the in the cut part of FIG. 1 can be seen. The Nipkow disk 140 fulfills together with their associated housing the task as a measuring surface in the modified Kelshauswerter 110 and mechanically scans a small growth area by transmitting light from the light sources 112 through successive holes of the Nipkow disk 140 reach the photomultiplier tubes 150 and 151 leaves. Depending on the incident light bundles through the photomultiplier tubes Electrical signals developed 150 and 151 are analyzed and used to generate video information for taking an orthophoto of yeasts and appropriate error signals for controlling the scanner 118 that induce him to adopt both the appropriate elevation and tilt, which correspond to the scanned growth area. In accordance with the increase or Electrical signals developed in the Z position of the scanner 118 are then generated to facilitate the recording control a slope shading map corresponding to the orthophoto; this can be done at the same time as the Record the slope shading map, as will be seen more clearly below will be.

The simplified scheme of FIG. 3 presents a section of a stereo model, the two slides 115.116 corresponds to One must remember exclaim that the stereo model discussed is just a projected image; however, it can be very easily understood if you think of it as a real model with a profile or surface in three Introduces dimensions. The profile is characterized by the geo-

5 m) is represented by a black line and the order of the corresponding shades if the increase is black-gray-white, then of course there is an adjacent gray line

5 an interval from 305 to 310 m and a white line adjacent to this gray line an interval from 310 to 315 m. If you record in this form, you have the option of not just changing the elevation easy and safe to set, but

o to also determine the sign of the increase change (upwards or downwards). If a slope shading card and an orthophoto are recorded in this way, brings the superimposition of the layer lines, which are clearly visible as the surface

Corresponding colors come according to a key for representation, which consists of three or more elements for representation the altitude information.

Details of the scanner 118 can be found in the views of FIG. 6, 7 and 8. As can be seen, the scanner 118 includes a Nipkow disk 140 which is rotatably installed in a housing 160 . A motor 162 is on the housing 160 for driving the

metric location of the registration points of the light images projected from the two slides 115, 116 over their entire overlap area.
As can be seen in this way, the projected
The stereo image can be viewed as having a sectional profile indicated by 139. The profile
139 is determined by the increase on which
corresponding light bundle parts passed through the slides 115, 116 intersect which
define the focused image. So it's on the left
Side of FIG. 3 a point A with an increase
shown, which corresponds to the point of intersection of the light bundles indicated by the solid lines;
these go through parts of slides 115 and 116,
that define the same image detail. Similarly, 15 a given height interval on which the servants highlight points B and C at special elevations, the fall shading map, shown on the ortho, which represents the intersection of the intersection of the dashed and dotted lines through the photo an effective topographical map.

correspond to th bundles of light; even these get to Though the slope shading map as one

those points from the slides 115, 116. With each row of lines of different shades plus a pair of light bundles that appear in pictures on the two days, it is probably clear that the slides in this regard from a common point in the ground also apply to other types of the Belonged to the illustration, the cut takes place at a height that corresponds to the development of different elevation intervals anwen-sea level of the terrain point. The evening leaves. For example, arrangements can be scanned as the goal of a stereo effect in various dotted and dashed lines, following the geometric division of the light from lines of variable widths or lines grazing both projectors on their associated photomultiplier.

A partial section from a typical orthophoto, as is the case with the operation of the described system 30
can be recorded is shown in FIG. 4 shown.
How to get from the illustrated part of the orthophoto
can see, the photographic details of the original aerial images represented by the two slides are attached to the orthophoto re 35 Nipkow disk 140. The whole scan is produced. In fact, it is now because of the way in disk mechanics including the housing 160 that the level of light intensity and the cathode can be adjusted in the vertical or Z-direction with beam luminance when operating the invention- using the Z-axis drive spindle 165 and of the Z-axis system, it is quite possible to move a senmotor 166. A display counter 168 is to be reconstructed orthophoto which is still photographically coupled to the scanner 118 in order to provide a display with phical points of detail which are contained in the original scanner elevation which the user can no longer easily read from initial slides. In addition, the Nipkow disk housing 160 can be found. In addition, however, the new one appears to be structured around a photograph parallel to the Y-axis, since the photographic detail can be tilted on axis by means of a servo motor, corresponding to the actual Cartesian coordinates of the 45, which is responsive to tilt signals, to correspond to inclined scanner 118 Film layer exposes image areas for better correspondence with

the actual terrain. Of course, the tilt control of the Nipkow disc is independent from the sample and increment control of the 50 sampler. For some applications, a Tilt control may be unnecessary, so that a simpler arrangement can then be provided.

The scanning disc housing 160 is provided with two pairs of windows, which are located on opposite sides

Approximation lines are mapped in a manner that 55 th of the disk 140 are arranged. The one, here allows the slice lines to be easily and reliably established as the scanning window 170 explained, place on the lower part. In the case of the particular two housing 160 in FIG. The window shown in FIG. 6 is used to play the gradient shading map for increasing the area of increase of the projected, scan change by recording in three different th stereo images at any given moment to line types that are defined by the shades of white, 60. The other, which can be defined as synchronous window 172 be gray and black in the sequence for a continuous change of elevation and in the upper part of the housing 160 in ongoing change of elevation. The window shown in Figure 6 is used to display lines and numbers. The different increase intervals under raster sync pulses in connection with the differ in that they are generated in the different Nipkow disks 140 , as will be shown below, each shadow being explained in more detail. This synchronization recurs in the sequence. Thus, if pulses are given by light from a light source 176 for a certain map section a level when passing through the synchronous window 172 of 300 to 305 m (with an increase interval of a line synchronous photocell 174 and a raster

is, as a true orthogonal projection, its corresponding points in true to size, more horizontal Relationship without distortion due to the point of view.

The F i g. 5 gives a partial image from a slope shading map, which corresponds to the partial orthophoto image of FIG. 4 corresponds. The detail shown in detail in Fig. 5 indicates how the sloping shade

synchronous photocell 175 produced. As shown in FIG. 1, the light goes from the slides 115, 116 through the window 170 in the housing 160 and through the running Nipkow scanning holes towards the photomultipliers 151 and 150, respectively.

Signals containing information relating to the elevation of the scanner 118 are developed for use in recording the slope shading photo by a slice line interval reading mechanism 178 coupled to the scanner 118. Back springs (not shown) are incorporated into the suspension mechanism of the scanner 118 to counterbalance the weight of the moving elements and to balance the torque required on the Z-axis servo motor 166 when the scanner 118 is raised.

F i g. 9 shows a Nipkow disk 140 as used in the scanner 118 . This particular scanning disc 140 includes a number of Abtastlöchern 212, an equal number of Zeilensynchronlöchera 214, and a number of raster synchronous holes 216. As can be seen, the Zeilenabtastlöcher are arranged in three groups 212, namely one group for each of the raster synchronous holes 216. Within a individual group, which corresponds to a grid, the holes 212 are shifted to gradually smaller (advancing clockwise) radial distances from the disc center. Thus, when the disk 140 rotates counterclockwise within the disk housing 160 of the scanner 118 (FIG. 6), each scanning aperture 212 in turn passes the scanning window 170 and exposes successive lines of the scanned raster to the photomultiplier tubes 150, 151 Light is given the opportunity to reach the corresponding photocells 174 and 175 through the synchronous window 172 and through the matching line synchronous holes 214 and raster synchronous holes 216. These photocells and appropriate associated circuitry in turn generate appropriate sync pulses which are used in handling the video signals derived from photomultiplier tubes 150 and 151. In this particular arrangement, the Nipkow disk is set up so that it rotates at 3600 rpm. The disk has three groups of 15 line scanning holes such that scanning is thus achieved at a rate of 180 rasters per second, equal to 2700 lines per second, with a resolution of 15 lines per raster. The scanning window area is 8.5 mm in the ^ dimension to 2.4 mm in the Y dimension.

A simplified block diagram of the system described is shown in FIG. This figure shows two light sources 112 in connection with two transparencies 115 and 116, a scanner 118 with a scanning disk 140, two photocells 174 and 175 and two photomultiplier units 150 and 151. As in FIG. 1, the scanner 118 is mounted on a scanner carriage 119 which is arranged to control the movement of the scanner 118 in the X and Y directions. The photomultiplier 150 and 151 are coupled via amplifiers 180 and 181 to a dead time compensator 183 and to a signal selector 190. In addition, the output terminals of amplifiers 180 and 181 are coupled to a light intensity control stage 185 to complete a feedback loop for controlling the light intensity of sources 112 . The photocells 174, 175 are coupled to line and raster synchronizing circuits 186 , which in turn are connected to the dead time compensator 183 and to various other system parts in order to process the video information derived from the photomultiplier 150, 151 in accordance with that generated by the photocells 174 and 175 Control sync pulses. From the output of the dead time compensator 183 , double channels of video signals are coupled to a Z-axis control stage 192 via amplifiers 188 and 189 with automatic gain control. Signals are also passed from the output of amplifiers 188, 189 to a tilt control circuit stage 194 which controls the tilt of disk 140 in scanner 118.

In a manner still to be described, the better of the two video signals is selected by the signal selector 190 and sent by it to a recorder

ao 200 which includes two cathode ray tubes 202 and 203 for recording the orthophoto and the slope shading map, respectively. The slope shading map is recorded in response to signals picked up by recorder 200 from a group of slice line interval switches 196; these are coupled to the scanner 118. A license plate marker 204 is coupled to the recorder 200 for generating appropriate license plate signals to mark specific points in the recorded photos as desired. The recorder 200 is attached to a recorder carriage 206 which is adjusted together with the scanner carriage 119 in accordance with signals from an X-axis control section 207 and a Y-axis control section 208.

In the automatic operation of the system of FIG. 10, the user first introduces a precise stereo model by appropriately adjusting the optical imaging mechanisms 113 (FIG. 1) in order to bring known surveying marks on the slides 115 or 116 to congruence, and also sets the carriage to the desired starting point . In addition to setting the scanner carriage 119 to the starting points of the X and Y coordinates, the Z carriage is adjusted to the corresponding height of the stereo image at the starting point and the system is put into automatic operation. In the automatic mode of operation, the scanner carriage 119 traverses the image in the Y direction and, at the end of each traverse, jumps a preselected distance in the Z direction, as indicated in FIG.

In this mode of operation, the overlapping parts of the projected images from the two slides 115, 116 are scanned simultaneously in order to supply corresponding electrical signals which represent the terrain. The scanning is done mechanically using the Nipkow disk 140. The electrical signals obtained from the photomultiplier units 150, 151 are analyzed in the Z-axis control stage 192 for the temporal coincidence of related elements in order to determine the error or the deviation in the elevation of the scanner 118 from the actual image elevation.

The resulting error signal is fed back from the Z-axis control stage 192 and used to raise or lower the scanner 118 along with its Nipkow disk 140. This

909 520/132

ίο

The system part therefore forms a closed loop of the height servo mechanism.

A simple illustration of the manner in which signals from the photomultiplier tubes 150 and 151 can be analyzed to develop a corresponding altitude error signal is provided with reference to FIGS. 11 and 12 given. F i g. 11 is a simplified, schematic sketch and shows the light emitting from each of the light sources 112

correlator 234 and a Z-plus correlator 235 are arranged to receive signals from the corresponding, labeled P1 and P 2 photomultiplier tubes. As can be seen, each of the photomultiplier signals is input to one of the Z-correlators directly and to the other Z-correlator via a delay chain. So every correlator used for height sounding receives video signals from both photomultipliers, where

bundles which pass through the slides 115 and 116 respectively to the one signal at the one correlator and the one in order to intersect at a point P which is delayed at the second correlator. Since each of the correctors 234, 235 operates to provide an output which is its maximum

value in the case of temporal coincidence of the two input

whose X, Y and Z coordinates depict the position of the photographed point of the terrain. After the cut at point P , the light beams continue to come on

the photomultiplier tubes 150 and 151, which has 15 signals, takes when the sampling from PI and P 2, respectively, are distinguished. First, let the model surface migrate out, the output signal

from one Z correlator, while that from the other correlator decreases. The output signals of the two Z-correlators 234, 235 are

assume that the Nipkow disk (not shown) is itself
located in the position in which it is the picture at the correct, indicated by the dashed line R.
Height scans, and that the Nipkow disk is in ao hurry filter chains 238 to an electronic switch of an elevation which is placed on the image slice line at 260, where it corresponds to a repetition frequency from point P. If a scanning hole is to be patterned, which is located with the frequency of the servo point P, both light beams go through the motor power source is synchronized (in this the disk hole to the corresponding photodevice is shown with 400 Hertz). The output of the multiples 150, 151 concurrently with the result as switch 260 is a Z or height error signal such that the signals developed by the photomultiplier tubes 150,151 of the appropriate size and polarity for the Z axis coincide in time as determined by control of the scanner 118 By scrapping the simplified waveforms labeled., 4 into signals from filters 238, the two of FIG. 12 are shown. If the Nipkow disk is moved to signals, one positive and one negative, from the dashed line H , it is too high, 30 alternating with a 400 Hertz frequency to the and the light beam from the slide 115 (if Z-error output liters in connected in a manner assuming that the scan in Fig. 11 of which automatically advances the signals while maintaining the two left to right) through to the existing differential polarity combi-photomultiplier 151 you see before the corresponding one. In this way, each signal from the bundle from the slide 116 to the photomultiplier filter 238 serves as a back-reference for the other signal fan 150 passes through. The result is a pair so that there is no need for any further back-reference, of waveforms that have the same general effect through the corresponding delay stages

The shape is retained, but the time delay introduced in the temporal relationship 231 and 232 is thus in accordance with the type of waveforms B in FIG. 12 that they are a special function of the correlating. On the other hand, if the scanning disc is too low 4 ° th scanning frequency of the image detail. If the timing, as indicated by the dashed line T , is so delay too short, the light beam from the slide 116 goes to the error signals in response to the indicative photomultiplier 150 before the corresponding light from the scanning elevation develops inappropriately the slide 115 for photo multiplication, while the corrector 151 goes if the delay time is too long; in doing so, the waveforms are developed between the original and the delayed ones, which are similar to the waveforms C in FIG. 12 gerten signals are not sufficient to produce satisfactory

Develop error signals.

In a system such as this, in which various time delays for signals are pre-supplied as a measure of the height error of the sampling 50, which is associated with multiplying correlators disk 140. Although the signals are generally used to develop an error signal,

which relates to the time shifts between corresponding elements of two separate input signals, the best delay is one

the signals to take into account whether they coincide in time or whether the one turns earlier than the other. Furthermore, there is a special one

Time delay provided at the input stages of the correlators of the error signal generator, the relates specifically to the sampling frequency; this is determined by the Nipkow disk and the image detail, to which the system should respond.

The output of a corrector shown in FIG. 15 can be viewed as a function of the time difference between the two input signals received 150 and 151 , in more precise 65. The effective resolution limit of the image scanned through the details in the block diagram of FIG. 13 is to be prayed for. In this figure there are two delay draws to the width of the scan holes in scan line chains 231 and 232 along with a Z minus. It turned out that the useful

are shifted. Sign and magnitude of the delay between the respective signals developed by photomultiplier 150 and 151

are not as well defined as those in FIG. 12 pulses shown, it is possible on the basis an examination of corresponding similar elements in

occurs. If the signals coincide, the height is correct; if these signals are not exactly in phase, will the increase in the scanning disc adjusted according to the resulting error signal.

That portion of the Z-axis control stage 192 in FIG. 10 which develops the height error signal along with certain other control signals in response to video signals it derives from the photomultiplier.

11 12

Resolution limit occurs for an image detail that is patterned around a 400 Hertz signal for which Y-Ge is approximately equal to the hole width. If the correlation level is close to the effective resolution limit, it can be slowed down automatically by means of an image increase with fine, filierarbeit. The output photographic details, so each associated 5 signal from the electronic switch 262 is also a photomultiplier signal that has approximately the shape of a triangle with a tip attached to a tronic switch 260 to one together with the Z error signal Z-threshold circle placed the point of best alignment with the scanning hole 264 , which feeds a track elimination control stage 265 , and has a time period which is greater than that to abort the profiling work when the correction actually for scanning the particular image detail io lation level below a predetermined The threshold required time, approximately the amount of Dop- decay, indicating that the terrain signals are not pelte the time required for the hole to be adequate for self-profiling or to travel over its own distance. Otherwise, if the Z-error signal becomes too large, the specific image detail at the effective resolution limit indicates that the scanner lies on the image slice line of the scanner, that is, when the detail has lost a lateral 15. A track elimination signal is developed in the event of expansion of approximately the width of the scanner of each of these two boundary conditions, then the duration of the pulse produced by the associated and used to feed a signaling device, photomultiplier, is approximately equal to the attention of the user to the fact the time, which is important for the scanning hole to steer that the automatic tracking is necessary, is interrupted by a distance equal to three times ao.

to traverse its own expanse. As already mentioned, the Nipkow disk 140 is only produced when two such signals are sent to a correlator - also a pivot about one to the Y axis, a useful output allele axis is able to better adapt to the terrain in signal when to join a certain inclined revenge. By tilting the degree of overlap between the two input scanning discs 140 in this way, better signaling will result. If the one of the input signals signal-to-noise ratio for the correlation output signals are delayed by a certain time interval, and the parallax interference that is supposed to be developed, the time delay should be such that the signal overlap is not completely prevented or eliminated in an advantageous manner in sloping terrain min will. It has been found that the best time is at least reduced. Signals for driving the tilting delay for the control circuit 194 shown in FIGS. 13 and 14 are also obtained from the differential correlators in the magnitude scanning work. To carry out this, the voltage is two to three times the time it takes the scanned line to probe hole at the center of the scan in order to split one of its own widths and to travel through the signals for the two halves independently. This time delay 35 is checked in order to determine the individual height error signals in accordance with a maximum resolution of the which are then compared in order to reliably determine tilt errors in the image details to which the system is to respond. The toggle error signal developed between maximum sensitivity and down is used to drive the toggle control circuit 194 (FIG. 10) probe elevation error and maximum range. The toggle error signal is passed through a range via which the system develops such a circuit that can respond to the one for the altitude errors. In a special embodiment, time delays of 20 microseconds are used. A block diagram of the toggle control circuit 194 is provided, two and a half times the time shown in FIG. As put in the circle of Fig. 13, in which a hole travels across its own width 45, signals from each of the photomultiplier units P1; The Nipkow disc has holes with PI over first paths, which contain the delay networks 241 0.2 mm in diameter in a mean radial and 243 , at correctors 244 and 245 at a distance of 65 mm from the center at a rotary, where they with undelayed , from the other number of 60 revolutions per second with a photomultiplier directly following scanning speed of 2.5 m per se- 50 signals inputted into the correlators. The correspondence customer. lator output signals are then passed to an electronic circuit 242 bypassing the output tronic reversing switch 268 , which by clamping the Z correlators 234 and 235 to develop a line sync pulse from the line sync part signal that is an average of the off - The synchronous circuit 186 triggered, monostable output signals from the correlators 234 and 235 . 55 multivibrator 269 is. Under the control of the mono-Simultaneously, the signals from the two photostable multivibrators 269 are the connections multiplier tubes Pl and Pl also directly between the input and output terminals of the (without delay) in a Z-Fühlerkorrelator 236 electronic switch 268 at the center point which compares the undelayed signals of each line scan in reverse. The twofold and one large output signal develops when the output signals from the electronic switch 268 height error is small, provided that some are then applied via separate filters 248 to an electronic switch 267 , where the synchronous ones are present, via separate filters 248 to an electronic switch 267 which is synchronous. This signal is a measure of the correlation between the input signals and the degree of follow-up of the photomultiplier signals. The output frequency of 400 Hertz is carried out in a manner output signal from the Z sensor correlator 236 is filtered in 65, which is filtered with regard to the development of a filter stage 239 and then passed on to the electrical Z error signal in the circle of FIG. 13 is applied tronic switch 262 , where it periodically resembles. The circle in FIG. 14 thus ensures a comparison between the two halves for the different halves, which is made with the signal from the UC circuit 242

10

The integral becomes with that shown in FIG simple circle only approximated, however the depicted circle is quite good as a means of revealing the signal correlation is effective.

The Nipkow disk 140 is driven so that between successive line scans there is a dead time. This means that the successive movement of scanning holes across the scanned grid excludes a smooth transition from one touch line to the next. if the spacing of the scanning holes is set up to ensure an overlap, which is how the Photomultiplier 150 and 151 a considerable increase in light intensity when the one scanning hole Leaves grid and enters the next scanning hole. Conversely, if there is a gap between consecutive Line scanning is provided, the light is dimmed for an instant when the Scanning from the one line scanning hole to the

height error signals developed every line scan. If the error signals are the same, this shows a constant height and means that no tilt correction is necessary. However, if the one Half of the line scan shows a larger height error than the other, the result is one Incorrect tilt display in the form of a tilt error signal at the output of switch 267, which is used for Tilt servo motor (Fig. 18) is directed to change the tilt of the Nipkow disk 140.

A particular circuit which can be used to serve as a correlator in the arrangement of FIGS. 13 and 14 is shown schematically in FIG. The correlator circuit of FIG. 15 includes two transformers 271 and 272 coupled to receive input signals shown as M and N. The output windings of the transformers 271, 272 are coupled to resistors 280 to 287, which in turn

again, as can be seen, on diodes 274 to 277 to the next. Would that be coupled out of it are. An output signal is not compensated for from a generating dead time between successive lines of common connection of the diodes 274 to 277 during scanning, so this would result from this Bridging by a capacitor 289 results in a large, unrelated compensation process took. in the video signals, which the effectiveness of the correction

In the case of the described arrangement, the signal generators would be reduced. The dead time compensator Correlation is extremely important for the appropriate self-183 is therefore arranged in order for the required Control of the scanner position; to provide particularly advantageous compensation. The operational details of the Results are obtained through the use of the multi-dead time compensator 183 can be found in the circuit diagram Obtain the corrector, see in Fig. 15 the image of Fig. 16, which shows the arrangement of the com is. The diodes 274 to 277 provide a capacitor for one of the photomultiplier channels together with resistors 280 to 287 for one shows.

Approximation to a quadratic current voltage In the circle of FIG. 16 becomes three with 252,253

relationship. The two transformers 271, 272 and 254 drawn switches through the line are used to control the two input synchronous circuit 186 A , which receives the two polarities through the line signals M and N. 35 synchronous pulses 259 is triggered. Video Signals The output voltage e ₀ on capacitor 289 can be written from a preamplifier 180 or 181 entering amplifier 250 as an input and out of cathode amplifier 258 as video output signals. During a line scan, switches 252, 253 and 254 are in the position shown. The video signals are thus represented by the circle in FIG. 16 is passed and, at the same time, a capacitor 256 is charged to an average level of the video signals. Just before the end of 287 and C the capacitance of capacitor 289 is. 45 line scanning is provided by the line sync photo-Here M + N is supplied by the diode 274, cell 174 a line sync pulse 259 is generated. That if M + N> 0 , and through the diode 277, if line synchronous circuit 186/1 then works towards it, M + N <0. Similarly, M- N is provided to diode 275 through the position of all three switches 252-254 if M-N > 0, and changing the input video signal from off through diode 276 if M-N <C 0 is. The diodes 50 and disconnect from the holding capacitor 256, 275 and 276 have reversed polarity, however, to connect the holding capacitor 256 to the output side of the circuit. The retention process provided in this way has as a result a blanking interval level that does not differ significantly from the normal signal. This process is particularly important in bright areas of the sculpture, where

_ ^K

f {(M + Nf - (M- Nf] dt,

i (i)

where K is an arbitrary constant of proportionality, R is the resistance value of one of the resistors 280 to

Effect subtractions. Equation (1) is simplified to

e _n =

4-K

R-C

■ I

M-Ndt,

(2)

so that the output voltage is a measure of the average product of the two signals and thus of the 60th
Degree of correlation between them. For example, if M and N are oscillating signals with random properties, the product has many positive and
negative contributions and therefore a low average; if, on the other hand, M and N are identical, the strength of the sources 112 is lightened and the instantaneous values of the products increase positively at all times, and thereby the probability that the useful form a result that does not cancel each other out. The signal is above the noise level. In the case of surfaces required by equations (1) and (2) - high transparency, the light output is reduced -

otherwise the dark signal at the end of the track (for
Absence of overlap of the scanning holes)
would be very disturbing.

The luminous intensity control circuit circuit shown in Fig. 10 is arranged to provide a reasonable signal
for the video analysis circuit, even in the event of quality defects in the slides. In the
The light-

set to the life of the projection light sources 112 increase. The light level control circuit 185 contains two magnetic amplifiers, one for each Lamp 112 powered by signals from photomultiplier amplifiers 180 and 181 in an array which completes the feedback path and for a closed servo controller loop provides for the lamps 112. With the help of this arrangement, their light intensity is changed in such a way that the

The X servomotor control circuit 323 then proceeds to feed the Z stepper motor 311 by Generated pulses with a predetermined repetition frequency. These pulses are counted by counter 325 5 counted, which shuts down the .X servo motor control stage 323, if the number indicates the setting of the X-step selector 326 reached.

That from the Y limit switch 318 to the reverse control circuit 321 applied signal initiates operation

Cut level at the output of the amplifier 180 io of the reverse circuit. Once in action and 181 sets appearing signals at the same level, the inversion control circuit 321 follows one in front the limits of the light intensity control circuit - specific work sequence. Circle 321 lays first circuit 185 is held. The light intensity control - a reduced drive voltage in the forward circuit can also be used to direct a direction to the Y-speed control circuit 320 constant light level for different image parts 15 for a short period of time during which the Abso to ensure that the light intensity is delayed at the corners of the truck. Next is a The image field does not show the opposite sign as a result of the greater distance between the drive voltage drops between scanner and light sources. The applied the Y-speed control circuit 320, the The highest luminance of the lamps 112 is limited, now the speed of the scanner carriage 119 is limited so that the life of the projection lamp does not degrade ao zero and then cause it to turn on is shortened impermissibly. It is also a voltage normal speed in the reverse direction divider provided for the light control, so that the device can accelerate. In this way, the Luminance of the lamps 112 as required by deceleration of the scanner carriage 119 Hand controlled. Time essentially equal to that for acceleration

The AT-axis control circuit 207 and the Y-axis 35 of the scanner carriage at normal speed control circuit 208 were used to make the scanner carriage 119 do when its direction of travel is reversed.
to drive in the X or Y direction and also Si- Should the automatic tracking of the track normal

To provide signals that similar adjustment mechanisms for advance, the scanner carriage 119 continues to control the recorder carriage 206. Details of how to hike back and forth at normal speed in this particular part of the system of FIG. 10 can be found. However, if that is found in Fig. 17, the scanner carriage 119 Z sensor signal with the indication of a bad correlation degree with the means for moving in the Y direction in the signals from the photo counter control of a Y servo motor 310 (= 134) and multiply by the Y-speed control in the ΛΓ-direction under the control of an X-step circle 320 is received, namely from the Z-tracking motor 311 (= 136) shows. The scanner carriage 35 lerkorrelator 236 via the switch 262 of Figs. 13, 119 is mechanically connected to an .Sf-resolver 314 and then the speed of the Y-servo motor Y-resolver 315 is coupled, the synchronizer in a 310 is reduced as a result of the control, the Contained by the arrangement in which control signals are supplied to the on-Y speed control circuit 320 so apply to appropriate servomotors in the recorder that the correct scanning information can be developed on a small carriage 206 in order to derive its location at 40 ren speed. Should be consistent with that of the scanner carriage 119 control. the Z-surge circuit 264 of FIG. 13 depending on the X and Y limit switches 317 and 318, the input signals applied to it also determine that it is mechanically coupled to the scanner carriage 119 in order either to reduce the degree of correlation inappropriately or to shut down the drive mechanism whenever the Z error is too large So a signal from which the limit of crossing is received in a particular 45 lane drop control circuit 265 which has reached the Y-Ge direction. speed control circuit 320 causes the over-

The Y servo motor 310 is traversed by a control signal across the field of the stereo model through the Abaus a Y-speed control circuit 320 to interrupt the truck 119. Under these activities which is coupled to signals from a stalls is a warning signal as an indication of the pre-reversing control circuit 321, seen from the probe correlator 50, that the tracking of the track is interrupted 236 and from the lane cancellation control stage 265 which is. During the changes in the movement F i g. 13 to receive. The X stepper motor 311 provides the speed of the scanner carriage 119 is driven in response to signals, the Y-speed control circuit 320 a signal that is on the luminance control of the cathode ray tube from a Z stepper motor control stage 323 stir. A counter 325 is applied to the Z-step 55 in the recorder 200 to control the luminous switch motor control circuit 323 in accordance with the density in accordance with the speed of the setting an X-step selector 326 to adjust the probe carriage 119 in such a way that the orthocouples. photo and recorded in the slope shading map

When operating the arrangement of FIG. 17 is drawn in shades by the speed Z-step selector a certain Af increment 60 keits Changes of the scanner carriage 119 unaffected set, and the Y-speed loop control will remain.

Circuit 320 is set to auto traverse a portion of the particulars shown in FIG. The Y servo motor 310 then drives the order, which is responsible for the height and tilt control of the The scanner carriage 119 has to do across the field of the scanner 118 is with a little more single stereo image in the Y direction. If a limit 65 units in the block diagram of FIG. 18 shown. In the Y-crossing is reached, gives a certain F i g. 18 is the scanner 118 in mechanical coupling Y limit switch 318 signals to the ΑΓ servomotor to the Z servomotor 331, the Z limit switch control circuit 323 and to the reversing control circuit 321. 333 and the layer line interval switch 196.

909 520/132

17 18

posed. The scanning disc 140 is improved on the scanner 118 disc 140 , provided that the image is mounted and arranged so that it is not blocked by one to. In practice, this means that the F-axis parallel axis can tilt the scanning disk 140 on a certain motor 335 with the aid of a tilt servo. A maximum Z-error and gate value must remain limited, which is coupled to the amplifier 336 so that it depends on a Z-error 5 position of the scanner 118 in the stereo area, receives signal (FIG. 13) and in At the outermost edges of the stereo model, the Z servo motor 331 controls it. A tilting maximum permitted tilting in the one direction interpreting control stage 338 is connected so that they tilt Hch less than that in the model center. Receives the maximum error signals and changes the tilt servo motor 335 permissible tilt in a given direction in accordance with these signals, as long as io significantly from one model edge to the other is not blocked by tilt limit levels. In the case of the special approach described here, the tilting limit circuit 339 can be applied. The edges of the stereo model developed in the Z-error generator of FIG. the projector farther away with the frequency of the servo. Are synchronized in the Symotor power source described here. The Z-error system is an arrangement which is provided for the learning signal to be either in or out of phase with the X coordinate position of the scanner carriage 119 and has a magnitude that exploits the statistical signals to establish the allowable tilt relationship to the degree of deviation between limit the height of the Nipkow disk 140. The way in which the scanning disc 140 and the increase in the area of the boundary signals are developed is intended to have in the incremental area of the scanned image. The Z error correlation with the description of FIG. 19 output signal is used when it is amplified in the amplifier 336 , which contains a circuit to the Entist, to feed the Z servo motor 331, in order to develop these position signals. An additional button 118 either up or down in the tilt limit of the scanning disc 140 will drive due to correct increase. When the scanner 118 imposes 25 of the scanner 118 , namely by changing its elevation, the height-layer mechanical shape of its housing and by the interval switch 196 are driven in revolving sequence, at its traveling limits necessary margin to develop an output signal, the one The tilting limit circuit 339 always gives a stop signal to the tilting shading map whenever the display shows that scanner height that is applied to the tilting limit of the scanning disk 140 for any drawing 200 in order to record the 3 ° position of the scanner 118 steer. In the circle to the tilt control 338 each shown to indicate an increase in the switches 196 directed beyond the limit in connection with the slice line interval of the tilt, it can be seen that three error signals are blocked. The circuit 339 , however, is set up to allow different levels of output signals for the three to cause toggle error signals to pass through various states of the switches produced 35 to the tilting servo motor 335 , which will, namely either both open, reduce a tilting angle of the scanning disc 140. It closed or both closed. For the one shown, maximum utilization of the tilting error signals is therefore the circle, the slice line interval signal has one of three values within the actually imposed tilting limits, namely either earth potential, + E.

or some potential midway between the 40 Figure 19 is a more detailed diagram of the signal both. As has already been described, selector 190 transmits and also shows the circuitry, this arrangement results in white, gray, or which is used to develop a composite signal corresponding to the black on the slope shading map indicating the scanner position and tilt, discussing the changes in elevation of the scanner, namely for use on the 118. The use of a cyclically revolving 45 tilting limit circuit of FIG. 18 and for the control of the key sequence provides in this way for the required of the signal selector 190. The signal selector 190 provides information regarding the direction of the increase in FIG . 19 contains two AND gates 350 and 351, which are coupled alternately in addition to the display of the occurrence of a, in order to interval the corresponding video changes between selected incremental inter signals from the photomultiplier 150, 151 . The scanning disk 140 is arranged to be applied via an OR gate 352 to the video by the tilt servomotor 335 to match the amplifier for the orthophotocathode ray tube to select recorder 200 . The selection of the thus obtain a better correlation between the signals better video signal through the gates 350 and 351 from the photomultiplier tubes, so the 55 is in line with the tilt angle of the Abtastabgeleiteten Z-error signals are improved kön- disc 140 and with the X-position Scanner carriage. The use of the Nipkow disk 140, however, is 119 controlled. A shown as a voltage divider 355 as the mechanical part of the scanning mechanism for the tilting angle guide is in this arrangement with its height probing places the usable area, sliding contact mechanically on the scanning disk 140 over which the slope of the terrain is coupled by tilting 60 in such a way that it is their currently existing tilting Nipkow disk can follow a restriction. The voltage divider 355 is open between. If the projected image is incident on the Nipkow disk + E and - E and connected in the middle to earth with an angle of more than 65 ° to the normal, so sen. A similar voltage divider 356 is similarly connected too little light through the disk holes to provide a signal to the photomultipliers 150, 151 because the 65 corresponds to that of the X-lag & of the scanner carriage 119. Disturb the edges of the pane window. The adaptation of the sliding contact of the voltage divider 356 is to the slope of the terrain is therefore a compromise- mechanically coupled to the carriage 119 and with question; the correlation is made movable by tilting the scan tool. The through the sliding contacts of the

19 20

speaking voltage divider tapped signals 362 and a Y'-axis motor 363 is driven, are applied to a summing amplifier 358- The drive motors 362 and 363 receive control, which develops an output signal; this is signals from the AT-axis and Y-axis control circuits Composition of the two from the spans 207 and 208 in such a way that the movement of the recording divider 355 and 356 derived input carriages 206 to the movement of the scanner carriage signals. The composite signal is chained to the 119.

Tilting limit circle 339 of FIG. 18 laid out in such a way that, with the reception from the signal selector when the tilt angle for a particular sampler- 190 selected signal is in a cathode ray position begins with an exceedance, amplifies those tilt tube video amplifiers 365 and sends them to the Error signals, as already described, are blocked. Cathode ray tube 202 for recording the orthode can, which is based on increasing the tilt over photos, to their electron bundle in the single-species Direct amount beyond. To modulate the signal from the sound with the video information that The output of summing amplifier 358 is developed as through photomultipliers 150 and 151 a second input to the AND gate 350 is immediate. The layer line interval switches 196 bar and to AND gate 351 upon reversal developed in Fig. 15 is on Inverse stage 359 applied. the cathode ray tube 203 for recording the

The operation of the signal selector 190 is so applied before slope shading, here the electron is, that a particular video signal is modulated from the beam and the requested slope video channel is selected which is recorded when the shading map is scanned. A brightening enhancer at best a right angle with the projected ao ker 367 is approximated by a luminance control circuit 368 light. In other words, the particular video signal selected and controlled by a counter 369 to control the cathode is that which corresponds to the image originating from the cathode ray tubes 202 and 203 in a particular projector at selected times during the scanning of the image; this, in turn, is the projector which, brightened to the correct luminance level, is closer to a line that becomes perpendicular to the ab- »5. In the case of the special, described arrangement scanning disk 140 is drawn through the scanning window. If, for example, the tilt angle is zero, the brightening occurs once during each raster in its center to record a selected one, then the signal selector 190 switches from the one line portion of the video signal occurring during the brightening interval to precisely record the other video signal. This action is controlled by the counter of the midpoint of the traverse of the carriage 119 30 369, which is reversed by the line sync pulses in the X direction. Similarly, if driven and reset by each raster sync pulse to the carriage 119, its place is just about to reset at the center point. The luminance control circuit 368 is in the ^ direction, switching between video signals in response to signals from the Y-axis when the tilt of the speed control 320 (Fig. 17) operates to scan disc 140 passes through zero. Others reduce the radiation density of the cathode ray tubes by combining the Z-position and the tilt angle when the speed of the scanner determines the selection of the preferred video signal carriage 119 is reduced. In this way, a sampling rate that corresponds to the polarity of the more coherent relationship between the radiance and the set signal from the summing amplifier is provided, which is advantageous. In the arrangement shown, a positive 40 th way is used to make the film exposure level independent of the sampling output from the summing amplifier.
358 to enable the AND gate 350 and, because of a deflection circuit 370 for controlling the beam deflection signal reversal by the inverter 359, to disable the operation of the corresponding cathode ray tubes 202 AND gate 351. Conversely, if the and 203 is connected to the counter 369 and the output of the summing amplifier 358 becomes negative 45 in accordance with signals from the label marist, the gate 350 is locked and the gate 351 freer 204 is controlled. The license plate marker 204 is given. So either the video signal no.1 contains conventional circuits for generating or the video signal no.2 at the input of the OR selected Lissajous figures, which the orthophoto gate 352 is available and is driven to the recorder 200 during normal loading and the gradient shading card created. The OR 50 points can be superimposed. The identifiers corresponding to Lissajous figures selected from the license plate marker 204 (see FIG. 10) for receiving a prevention signal are selected and concluded by the user so that video signals from recorder 200 are generally used to block particular points from internally can be if the license plate esse to mark in the processing area,
marker 204 comes into operation. 55 The automatic stereo mapping described above

The system 200 used in the special arrangement of FIG. 10 can be operated to produce photographic recorders 200 in somewhat larger individual maps which have a useful topographical unit in FIG. 20 shown. As can be seen, the information from two in the projection of a stereo recorder 200 includes a cathode ray tube 202 to present slides used for the image. The radiant tube 203 produced during the recording of the orthophotos and a cathode drive of the system described for recording the slope chat orthophotos and slope shading maps can be used; both are joined in a mosaic near a film table 360 to provide a complete set on which film sheets for exposure through a topographical map of an entire area provide the bundles of the respective cathode ray tubes in full detail. The manufacturing 202 and 203 can be attached. The cathode ray tubes are moved across the film table 360 so by creating an automatic one through the recorder carriage 206, which in the system considerably facilitates the creation of the X and Y directions by means of an X ' -Axis motor len a map from aerial photographs required time

significantly reduced the richness of detail and the accuracy of the resulting photo cards presented information increases and the existing for exact maps dependence on the limited The number of experienced card manufacturers and photogrammetry specialists who previously worked for such Purposes were necessary.

Claims (12)

Claims: IO 1.Automatic stereo mapping device for deriving information from a stereo image, with a scanning device serving to scan a differential surface area of the stereo image for the purpose of deriving video signals, which is displaceable over the entire image area and scans the differential surface area with separate line scanners to generate the video signals, and with Devices which respond to the video signals and indicate the height of the scanned image area, characterized in that the video signals are fed to dead time compensators (183) which eliminate the effect of the disturbances a5 occurring in the video signals due to dead times. 2. Stereo mapping device according to claim 1, characterized in that a main signal can be derived and stored during each line scan through each dead time compensator (183) from its corresponding converter (150, 151) , which signal replaces the main signal for the converter output during the dead time at the end of the line scan . 3. Stereo mapping device according to claim 2, characterized in that the converters (150, 151) are photomultiplier (Pl, P 2). 4. Stereo mapping device according to one of claims 1 to 3, characterized in that each dead time compensator (183) consists of a capacitor (256) and a plurality of switches (252 to 254) which can be actuated synchronously with a scanning device (140) so that the Output of the corresponding converter (150, 151) is connectable to both the capacitor (256) and to the device which compares the converter outputs during the main part of each line scan, and that the switches (252, 254) are controllable so that the converter output can be separated both from the capacitor (256) and from the comparison devices during the dead time at the end of the line scan, and instead the capacitor (256) can be connected to the comparison device. 5. Stereo mapping device according to one of Claims 1 to 4, characterized in that the comparison device for the outputs of the converters (150,151) is equipped with two correctors (234,235) which are suitable for comparing instantaneous converter signals with delayed converter signals and associated signals generate, from which a height error signal can be derived. 6. Stereo mapping device according to claim 5, characterized in that the signal emitted by the one converter (150, Pl) is the one correlator (235) directly and the other correlator (234) can be fed through a delay network (231) , while the signal emanating from the other converter (151, P 2) is fed to one correlator (235) can be fed directly through a delay network (232) and the other correlator (234). 7. Stereo mapping device according to one of claims 1 to 6, characterized in that the outputs of the dead time compensators (183) belonging to the converters (150,151) are fed to a device for determining the inclination which contains two correlators (244, 245) which are suitable for comparing the delayed and undelayed signals provided by the two dead time compensators (183) in order to generate a tilt error signal which indicates the tilt of the scanned image area. 8. Stereo mapping device according to claim 6, characterized in that the time delay of each network (231, 232) corresponds approximately to the time that the detailed scanning takes at the resolution limit of the system. 9. stereo mapping device according to claim 8, characterized in that the delay is approximately 20 microseconds if the scanning aperture of the scanning device has a diameter of 0.203 mm and moves at 2.489 m per second. 10. Stereo mapping device according to one of claims 5 to 9, characterized by a further correlator (236) which is used to assign the undelayed signals emitted by the converters (150, 151) and which generates a further assignment signal which can be used to interrupt operation of the device, as soon as the correlation between the converter signals falls below a certain level. 11. Stereo mapping device according to one of claims 5 to 10, characterized in that each correlator by approximating a quadratic current-voltage function, which is approximately the equation _ 4-K Γ
RC J M-Ndt follows, creates an assignment in the form of a multiplication, where e _{0 is} the assignment signal, M and N the input signals, K a constant, R and C the resistance or the capacitance of the correlator and T the period of the signal correlation. 12. Stereo mapping device according to claim 11, characterized in that each correlator (244, 245) is provided with two transformers (271, 272) which receive the signals M and N , and with several pairs of resistors (280 to 287) which the outputs of the transformers (271, 272) in several common nodes, and that several diodes (274 to 277) are connected between the common node and a capacitor (289) , via which the assignment signal can be developed. In addition 3 sheets of drawings