EP0039263A1 - Zweidimensionales Korrelatorgerät - Google Patents

Zweidimensionales Korrelatorgerät Download PDF

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Publication number
EP0039263A1
EP0039263A1 EP81400544A EP81400544A EP0039263A1 EP 0039263 A1 EP0039263 A1 EP 0039263A1 EP 81400544 A EP81400544 A EP 81400544A EP 81400544 A EP81400544 A EP 81400544A EP 0039263 A1 EP0039263 A1 EP 0039263A1
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EP
European Patent Office
Prior art keywords
line
correlation
lines
image
signals
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP81400544A
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English (en)
French (fr)
Inventor
Pierre Tournois
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Thales SA
Original Assignee
Thomson CSF SA
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Publication date
Application filed by Thomson CSF SA filed Critical Thomson CSF SA
Publication of EP0039263A1 publication Critical patent/EP0039263A1/de
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    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06G—ANALOGUE COMPUTERS
    • G06G7/00—Devices in which the computing operation is performed by varying electric or magnetic quantities
    • G06G7/12—Arrangements for performing computing operations, e.g. operational amplifiers
    • G06G7/19—Arrangements for performing computing operations, e.g. operational amplifiers for forming integrals of products, e.g. Fourier integrals, Laplace integrals, correlation integrals; for analysis or synthesis of functions using orthogonal functions
    • G06G7/1928—Arrangements for performing computing operations, e.g. operational amplifiers for forming integrals of products, e.g. Fourier integrals, Laplace integrals, correlation integrals; for analysis or synthesis of functions using orthogonal functions for forming correlation integrals; for forming convolution integrals

Definitions

  • the present invention relates to the two-dimensional correlation in real time of an image obtained line by line and of an image in memory.
  • the device provides the image correlation signals for a certain number of lines with the image in memory, in time corresponding to a line scan.
  • the device according to the invention applies in particular to systems on board a vehicle and which provide images such that the lines are renewed by advancing the vehicle. More particularly, the device is applicable to radar, sonar or optical imagery which must necessarily operate in real time and for which the rate of renewal of the image lines is high and also to systems for which the volume and the consumption of means used must be reduced to the maximum. Among these systems, there may be mentioned the on-board systems for guiding, locating and resetting maps.
  • high definition sonar systems are used to visualize the seabed.
  • These systems consist of a transmitting antenna which sends signals in the form of waves, ultrasonic, electromagnetic, or infrared, in all or part of the surrounding space.
  • the signals received by the same antenna are processed to separate the energies coming from different directions.
  • the separation distance obtained depends on the angular resolution of the antenna, which is a function of the ratio between the wavelength ⁇ of the signals transmitted and the length L of the antenna, ie ⁇ / L.
  • a lateral vision radar antenna (called “side-looking” in Anglo-American literature) operating as a synthetic antenna, 1 that is to say say using the displacement of the carrier vehicle to synthesize longer antenna length.
  • the signals received are recorded on photographic film and then processed to restore the true image, the processing consisting in correlating the signals with the reference signal as a function of displacement. of the vehicle and the distance to the object.
  • the data collected is therefore important and the correlation treatments long. They are carried out optically by reading the film as described for example in an article by L.J. Cutrona et al (Proceedings IEEE, Vol. 54 no. 8, 1966, p. 1026).
  • processing operations are performed digitally because they are more precise and flexible, these processing operations being mainly focused on measurements of time of arrival, sorting and identification of signals.
  • the device comprises, on the one hand a correlator receiving simultaneously on these two inputs the two electrical signals of a line of the reference image and of a line of the scanned image providing a one-dimensional correlation line formed of points corresponds to the offsets of the two input signals and that it also comprises a summing device summing the signals for the points corresponding to the same offset, for all of the one-dimensional correlation lines of the two images, the summation signal providing a two-dimensional correlation line, and that the device provides a new two-dimensional correlation line, after each new scanned line of the image obtained by scanning .
  • Figure 1 shows an example of lateral vision imagery.
  • the antenna Mounted on the vehicle 1 moving in a direction yy ', the antenna transmits and receives along the beam F which intercepts the object plane along a line J parallel to the axis xx'.
  • the image points forming this line J correspond to a distance between L 1 and 1.2.
  • the resolution along yy ' corresponds to the angular width at half power of the beam F while the resolution along xx' is inversely proportional to the frequency band of the signals transmitted.
  • the image lines thus obtained are stored and used to be correlated with an image already in memory.
  • the one-dimensional correlation function of two signals s 1 and s 2 depending on the dimension x is: where X is the dimension of the space for which the function corresponding to an offset l along Ox is calculated.
  • the still image 10 has K lines of M points and the scanned image 11 has L line, such as J, of N points.
  • the scanning is done parallel to the direction Ox.
  • fig 2 we took the case of K less than L and M greater than N.
  • the K points corresponding to the same offset t are summed over all of the K lines to obtain MN two-dimensional correlation points C (l, m) for an offset m along Oy (2), these MN points forming a correlation line such as 13.
  • a correlation line 13 is obtained each time a line of the image 11 is renewed.
  • the proposed device makes it possible, thanks to the use of acoustic convolvers, to obtain a two-dimensional correlation line in a time interval which is generally less than the period of renewal of the lines of images obtained by imaging systems using a vehicle, as will be shown later in the applications.
  • the proposed device applied to imaging systems therefore provides the two-dimensional correlation function of two images in real time.
  • FIG. 3 shows the organization of the device for correlating the two images 30 and 31. Only two consecutive lines r l , r 1 1 of the image 30 and r 2 , r 1 2 of l have been represented. image 31. The two images 30 and 31 are correlated line to line, r 1 with r 2 then r 1 1 with r 1 2 , etc. in a correlating device 32. Each time two lines, for example r 1 and r 21 are correlated the correlating device provides a one-dimensional correlation line composed of points each corresponding to a certain offset l. In circuit 33 the points of all the correlation lines are added by offset l and when all the image lines 30 and 31 have been processed, circuit 33 provides a line of the two-dimensional correlation corresponding to an offset m in the direction of movement line by line of one of the two images.
  • the correlating device 32 can for example consist of a computer which can also include the circuit 33. Preferably, it will consist of an analog device formed by an acoustic convolver.
  • FIG. 4 shows the known principle of the elastic wave convolution device. It comprises a rod made of piezoelectric material 20, comprising at these ends two interdigitated transducers Ti and T 2 between which a pair of planar electrodes 21 and 22 is disposed.
  • the two signals from which we want to obtain the convolution F (t) and G (t) are modulated by a pulsation carrier w capable of generating acoustic waves in the bar 20.
  • the signal H (t) represents the convolution function of F and G compressed in time in a ratio 2, and in a time interval corresponding to the time during which the two signals interact over the entire length S of the electrodes 21 and 22 , along the axis of propagation. So if the two signals had the same duration only one point of the correlation function would be valid. On the other hand, if the two signals have a different duration, a number of valid correlation points is obtained equal to the difference in the number of points between the two signals.
  • acoustic beam compressors or a plate of semiconductor material placed between the electrodes 21 and 22 and the bar 20 are used.
  • each signal has two components called complex components.
  • the two signals are stored in the form of complex digital samples in random access memories of RAM type. To simplify, only the reading circuits of these memories have been shown.
  • the real and imaginary parts of the signal representative of the image scrolling line by line are stored line by line in the memories 40 and 41 while the real and imaginary parts of the reference signal are also stored line by line in the memories 42 and 43.
  • the digital samples of the stored signals are quickly read line by line at the rate of a clock signal H M supplied by the generator 46.
  • the clock signal H M is applied to the addressing devices 61 and 62 which supply the addresses of RAM memories 40, 41, 42 and 43.
  • the clock signal also controls the rate of analog-digital conversion of the samples read in the converters 44.1, 44.2, 44.3 and 44.4 so as to synchronize the sending of the two signals on two modulator circuits 45.1 and 45.2.
  • a modulator circuit for setting on a carrier frequency is represented in FIG. 6. It is of conventional type, namely composed of two multipliers 65 and 66 in cos (2 ⁇ f o t) and sin (27rf t), where the frequency f is supplied by a local oscillator 47.
  • the real part P of each of the input signals is multiplied by the term in cosine while the imaginary part P 1 is multiplied by the term in sine.
  • the two signals obtained are then added in a circuit 63 and the resulting signal is filtered in a bandpass filter 64 centered on f 0 of band B 0 as a function of the frequency of the clock signal H M.
  • the two signals s (t) and r (t) obtained at the output of the two modulators 45.1 and 45.2 are sent after amplification on the transducers of a piezoelectric convolver device 50, whose central frequency is equal to f and the band equal to B .
  • TH is the period of the signal of the control clock H M , N and M respectively the number of samples per line in the image memories 40, 41 and in the reference memories 42, 43, the signal durations s (t) and r (t) which correspond to each line read are respectively equal to NT H and MT H.
  • the signal u (t) is sent to a demodulator circuit 49 shown in FIG. 8, in which the signal is multiplied in circuits 82 and 83 by sin (2 ⁇ f 1 t) and cos (Z ⁇ f 1 t), the frequency f I being supplied. by a local oscillator 48 the two signals obtained then being filtered in two low-pass filters 84 and 85 whose cut-off frequency is close to B o / 2.
  • the two signals are sent in two sampler-coder circuits 55.1 and 55.2 controlled by a clock signal H T with a period 2 times smaller than H M and restoring the signals in the form of digital samples.
  • the M - N samples obtained are stored in a line of memories 57 and 58, at the rate of a clock H S of the same period as H m forming a two-dimensional correlation line.
  • the process thus described begins again each time a line is renewed in the process image.
  • the memories 57 and 58 are filled and correspond to the two-dimensional correlation of the reference image, with the image which has passed line by line over L lines.
  • the number of correlation lines at output can be arbitrary; however, from a number L of lines formed, the two original images which correspond to line i and to line i + L are entirely distinct.
  • the output signals of circuit 56 can be processed to obtain either the module or the phase, a single output memory then being used.
  • the device according to the invention applies to guiding a machine by resetting cards.
  • a machine follows a trajectory 72 and at each instant it acquires the image of a portion of terrain 70. It has in memory a reference map 71 composed of lines identified according to an axis system rectangular Oxy and whose ordinate is known there.
  • the navigation systems on board the device make it possible to provide an image at all times, the lines of which remain parallel to the axis Oy of the reference map.
  • the two-dimensional correlation line corresponding to this instant has a maximum whose position will make it possible to measure the abscissa x and to readjust the machine.
  • the device is applicable for aerial systems with radar and infrared and also for underwater systems with sonar.
  • the device can be applied to the detection of changes in terrain or seabed; in particular it can be applied to satellites taking into account the reduced dimensions for this type of machine.
  • the device described also applies to the recognition of shapes: the copy representing the shape to be recognized is then smaller than the image read.
  • the central frequency f o and the band B o of the convolver are chosen to be 50 MHz and 10 MHz respectively.
  • the duration MT H of the signal r (t) is equal to 40 us and the length S is close to 12 cm providing a reduced bulk.
  • the circuit 56 of FIG. 6 comprises an 8-bit x 300 buffer memory and a 16-bit x 300 accumulator. An addition operation being carried out in a time of 50 ns, period of the clock H T , the time to add 300 samples remains below MT H, ie 40 us using a single adder.
  • a two-dimensional correlation line is therefore obtained in 40 ⁇ s x 100, or 4 ms, using a single convolver.
  • higher operating speeds can be achieved by using several convolvers in parallel to process several lines in parallel.
  • the fastest digital circuits allow the calculation of a point of the correlation function in the same order of magnitude of time where the whole function is reconstituted by the convolver device, that is to say a speed ratio of around 100.
  • a line of the two-dimensional correlation between a line of 100 x 100 and an image of 400 x 100 is obtained in 4 ms using a single convoluting device.
  • this duration corresponds to the maximum duration that must be respected between two two-dimensional correlations images for two shifts depending on the progress of the vehicle.
  • This duration corresponds to a distance traveled of the order of 1 meter at a speed of Mach 1 and this resolution is of the order of magnitude of that sought, in general, for soil exploration systems.
  • the resolution obtained at a hundred meters is of the order of 15 centimeters.
  • the renewal period of an image line is equal to 15 ms and only the use of the proposed device makes it possible to obtain the two-dimensional correlation function in real time.
  • the digital memories 41, 42, 43 and 44 are replaced by charge transfer devices or C.C.D. These devices can have 512 stages and be controlled at a frequency of 10 MHz making their use possible. Also a charge transfer device can be used in place of an acoustic convolver.
  • this correlation is done on the intensities and not on the amplitudes.
  • the reference image and the scanned image are stored respectively in a single memory such as 40 and 42 in FIG. 5.

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  • Physics & Mathematics (AREA)
  • Mathematical Physics (AREA)
  • Engineering & Computer Science (AREA)
  • Theoretical Computer Science (AREA)
  • Software Systems (AREA)
  • Computer Hardware Design (AREA)
  • General Physics & Mathematics (AREA)
  • Radar Systems Or Details Thereof (AREA)
  • Measurement Of Velocity Or Position Using Acoustic Or Ultrasonic Waves (AREA)
  • Processing Or Creating Images (AREA)
  • Complex Calculations (AREA)
  • Image Analysis (AREA)
EP81400544A 1980-04-25 1981-04-03 Zweidimensionales Korrelatorgerät Withdrawn EP0039263A1 (de)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR8009386A FR2481489A1 (fr) 1980-04-25 1980-04-25 Dispositif correlateur bidimensionnel
FR8009386 1980-04-25

Publications (1)

Publication Number Publication Date
EP0039263A1 true EP0039263A1 (de) 1981-11-04

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EP81400544A Withdrawn EP0039263A1 (de) 1980-04-25 1981-04-03 Zweidimensionales Korrelatorgerät

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US (1) US4449193A (de)
EP (1) EP0039263A1 (de)
JP (1) JPS56168287A (de)
CA (1) CA1177173A (de)
FR (1) FR2481489A1 (de)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2165714A (en) * 1984-09-07 1986-04-16 Messerschmitt Boelkow Blohm Electro-optical aiming device
FR2656185A1 (fr) * 1989-12-14 1991-06-21 France Etat Armement Imageur convolueur micro-electronique.

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US4561067A (en) * 1982-06-23 1985-12-24 British Telecommunications Multi-channel cross-talk interference reduction circuit using modulation-multiplying-demodulation correlator
US4602336A (en) * 1983-05-16 1986-07-22 Gec Avionics Limited Guidance systems
US4990925A (en) * 1984-05-07 1991-02-05 Hughes Aircraft Company Interferometric radiometer
US4907287A (en) * 1985-10-16 1990-03-06 Hitachi, Ltd. Image correction system for scanning electron microscope
US4742233A (en) * 1986-12-22 1988-05-03 American Telephone And Telgraph Company Method and apparatus for automated reading of vernier patterns
US4882715A (en) * 1987-03-16 1989-11-21 Canon Kabushiki Kaisha Surface acoustic wave convolver with dielectric film of high non-linear effect
JPS63292495A (ja) * 1987-05-25 1988-11-29 Agency Of Ind Science & Technol 光−電気ハイブリット型連想記憶装置
JPH067240B2 (ja) * 1987-06-10 1994-01-26 浜松ホトニクス株式会社 光学的連想記憶装置
US5526298A (en) * 1987-06-10 1996-06-11 Hamamatsu Photonics K.K. Optical associative memory
JPH0269013A (ja) * 1988-09-02 1990-03-08 Clarion Co Ltd コンボルバ最適バイアス回路
US5267179A (en) * 1989-08-30 1993-11-30 The United States Of America As Represented By The United States Department Of Energy Ferroelectric optical image comparator
WO1993023816A1 (en) * 1992-05-18 1993-11-25 Silicon Engines Inc. System and method for cross correlation with application to video motion vector estimation
US5276636A (en) * 1992-09-14 1994-01-04 Cohn Robert W Method and apparatus for adaptive real-time optical correlation using phase-only spatial light modulators and interferometric detection
US5588067A (en) * 1993-02-19 1996-12-24 Peterson; Fred M. Motion detection and image acquisition apparatus and method of detecting the motion of and acquiring an image of an object
GB9722766D0 (en) 1997-10-28 1997-12-24 British Telecomm Portable computers
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US6771264B1 (en) * 1998-08-20 2004-08-03 Apple Computer, Inc. Method and apparatus for performing tangent space lighting and bump mapping in a deferred shading graphics processor
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US7242169B2 (en) * 2005-03-01 2007-07-10 Apple Inc. Method and apparatus for voltage compensation for parasitic impedance
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US7577930B2 (en) 2005-06-23 2009-08-18 Apple Inc. Method and apparatus for analyzing integrated circuit operations
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US7598711B2 (en) * 2005-11-23 2009-10-06 Apple Inc. Power source switchover apparatus and method
JP5174246B2 (ja) * 2009-09-17 2013-04-03 株式会社東芝 加算器
US10337851B2 (en) * 2015-04-02 2019-07-02 Ramot At Tel-Aviv University Ltd. Fast phase processing of off-axis interferograms

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FR2353185A1 (fr) * 1976-04-09 1977-12-23 Thomson Csf Dispositif correlateur rapide, et systeme de traitement des signaux d'un recepteur comportant un tel dispositif
GB1542853A (en) * 1976-08-31 1979-03-28 Secr Defence Charge coupled device correlators

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Publication number Priority date Publication date Assignee Title
FR2353185A1 (fr) * 1976-04-09 1977-12-23 Thomson Csf Dispositif correlateur rapide, et systeme de traitement des signaux d'un recepteur comportant un tel dispositif
GB1542853A (en) * 1976-08-31 1979-03-28 Secr Defence Charge coupled device correlators

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2165714A (en) * 1984-09-07 1986-04-16 Messerschmitt Boelkow Blohm Electro-optical aiming device
FR2656185A1 (fr) * 1989-12-14 1991-06-21 France Etat Armement Imageur convolueur micro-electronique.

Also Published As

Publication number Publication date
US4449193A (en) 1984-05-15
FR2481489A1 (fr) 1981-10-30
JPS56168287A (en) 1981-12-24
CA1177173A (en) 1984-10-30
FR2481489B1 (de) 1984-07-06

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