EP1573356A1 - Method for calibrating 3d image sensors - Google Patents

Method for calibrating 3d image sensors

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Publication number
EP1573356A1
EP1573356A1 EP03799433A EP03799433A EP1573356A1 EP 1573356 A1 EP1573356 A1 EP 1573356A1 EP 03799433 A EP03799433 A EP 03799433A EP 03799433 A EP03799433 A EP 03799433A EP 1573356 A1 EP1573356 A1 EP 1573356A1
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EP
European Patent Office
Prior art keywords
receiving array
light source
pixel
pixels
calibration
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.)
Ceased
Application number
EP03799433A
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German (de)
French (fr)
Inventor
Zhanping Xu
Christian Lang
Bernd Schneider
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Gesellschaft fur Sensortechnik und Automation GmbH
Conti Temic Microelectronic GmbH
Original Assignee
Gesellschaft fur Sensortechnik und Automation GmbH
Conti Temic Microelectronic GmbH
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Publication date
Application filed by Gesellschaft fur Sensortechnik und Automation GmbH, Conti Temic Microelectronic GmbH filed Critical Gesellschaft fur Sensortechnik und Automation GmbH
Publication of EP1573356A1 publication Critical patent/EP1573356A1/en
Ceased legal-status Critical Current

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Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S17/00—Systems using the reflection or reradiation of electromagnetic waves other than radio waves, e.g. lidar systems
    • G01S17/88—Lidar systems specially adapted for specific applications
    • G01S17/89—Lidar systems specially adapted for specific applications for mapping or imaging
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S7/00—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00
    • G01S7/48—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S17/00
    • G01S7/497—Means for monitoring or calibrating

Definitions

  • the invention relates to a method for calibrating 3D image recorders according to the preamble of claim 1.
  • 3D image recorders as are known for example from DE 198 21 974 A I, are used for distance measurement using the incoherent optical transit time method (modulation interferometry method).
  • the amplitude-modulated illuminating light reflected by the scene to be measured is demodulated (correlated) with a demodulation signal, for example an identical signal, and the phase relationship (correlation) between the transmitted and received signal is thus determined.
  • This phase relationship is used as a measure of the distance covered by the transmitted light.
  • an optoelectronic sensor in which, for referencing the light, is transmitted from the transmitter element used for illuminating the scene or a separate transmitter element to a reference object within the sensor and by means of a separate receiver or for receiving reflections the received signal from the reference object is acquired as a reference signal from the receiver provided in the scene and aging and temperature effects are derived therefrom.
  • distance information is also derived from amplitude modulation at the transmitter and a phase comparator at the receiver.
  • Manufacturing tolerances e.g. fixed pattern noise
  • temperature fluctuations and aging processes mean that the parameters of the different pixels in a receiving array differ from one another to different degrees. If these deviations become too large, it is necessary to calibrate the entire receiver array for each pixel. This is not possible with the above procedure.
  • the object of the invention is to provide a method for referencing 3D image recorders with which calibration of the receiving array is possible during operation.
  • the receiving array is illuminated exclusively with calibration radiation with a phase position that is at least largely homogeneous for all pixels with respect to the demodulation signal from a modulatable light source (e.g. LED, laser diode, etc.).
  • a modulatable light source e.g. LED, laser diode, etc.
  • the resulting receiver signals of the individual pixels are evaluated individually for each pixel, i.e. Deviations, disturbances or defects of individual pixels are recognized. This is the only way to compensate for pixel-specific deviations, which is extremely important for the detection and tracking of objects in moving systems.
  • the relative phase deviation between the pixels can also be recorded, and the signals of the pixels can thus be standardized to a reference variable.
  • the phase relationship between the transmission signal and the demodulation signal is preferably changed, which corresponds to a measurement with a virtual second distance, i.e. calibration is carried out over at least two virtual distances.
  • Phase position is preferably by a corresponding delay on the transmit or Demodulation signal causes relative to the other signal, so that there is no change in the actual distance between the light source and the receiving array.
  • the pixel-specific deviations relative to one another can in particular be evaluated independently of the actual absolute phase relationship for each calibration measurement from the knowledge of the phase shift between the at least two calibration measurements.
  • the phase relationship is preferably freely selectable, for example, it is tuned along a predetermined characteristic curve over a corresponding number of transmission processes. In this way, nonlinearities can be detected individually on a pixel basis depending on the distance of later target objects. This allows referencing at different virtual distances.
  • the 3D image sensor according to the invention has, in addition to the elements which are usually present, a reference light source which, like the light source of the transmission unit, can be modulated.
  • the reference light source is mounted in such a way that the complete receiving array is illuminated with an at least largely homogeneous phase position with respect to the demodulation signal for all pixels and preferably also approximately uniformly in terms of its brightness. That there is direct lighting without the use of reference objects or the like. If the receiver array functions optimally, each pixel should measure the distance or phase shift that is specified by the reference path and the set phase position between the reference light source and the demodulation signal.
  • a second embodiment of the invention provides for the calibration of the entire receiver array to redirect the illuminating light of the transmitter unit so that an internal connection between the transmitter and receiver array is created.
  • the external connection via the lighting of the scene is interrupted in this case, so that no transmitted light detours through an unknown scene and thus with an unknown phase shift to the pixels.
  • the internal connection is broken again in order to avoid a disturbance in the phase measurement.
  • These locking devices are configured, for example, by one or more mechanical changeover switches. In practice, however, attempts are made to avoid moving components as much as possible. In this case too, the phase relationship between the modulated transmission signal and the receiver signal is varied in order to carry out a calibration in the case of different phase positions (virtual distances).
  • a disadvantage of the conventional reference measurement, in which a known scene has to be recorded, is that such a scene is not always available, e.g. if the reference scene is covered. This problem is avoided by the invention described above.
  • Another advantage of the reference technology according to the invention is the possibility of referencing over the entire temperature range of the 3D image sensor without removing it from its installation location. It is the same with age-related drifts.

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  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • General Physics & Mathematics (AREA)
  • Radar, Positioning & Navigation (AREA)
  • Remote Sensing (AREA)
  • Electromagnetism (AREA)
  • Optical Radar Systems And Details Thereof (AREA)
  • Length Measuring Devices By Optical Means (AREA)
  • Measurement Of Optical Distance (AREA)

Abstract

The invention relates to a method for calibrating 3D image sensors. Work tolerances, temperature variations and aging processes result in that the various pixels in a receiving array deviate from one another to different degrees. The aim of the invention is therefore to calibrate the entire receiving array with respect to every pixel. During operation of the 3D image sensor there is usually no reference scene available with which every pixel could be calibrated based on known phase relations. According to the invention, the entire receiving array is illuminated at defined intervals exclusively with one modulated light source. Alternatively, the emitted light source can be used via a deflection device. Two different distances can be simulated by carrying out two calibrating measurements with different phase relations between emitted and received signal, thereby making it possible to detect distance-related errors for every pixel individually.

Description

Verfahren zur Kalibrierung von 3D-Bildaufnehmem Procedure for the calibration of 3D image recorders
Die Erfindung betrifft ein Verfahren zur Kalibrierung von 3D-Bildaufnehmem gemäß dem Oberbegriff von Anspruch 1.The invention relates to a method for calibrating 3D image recorders according to the preamble of claim 1.
3D Bildaufnehmer, wie sie zum Beispiel aus der DE 198 21 974 A I bekannt sind, werden zur Entfernungsmessung nach dem inkohärenten optischen Laufzeitverfahren (Modulations-Interferometrieverfahren) eingesetzt.3D image recorders, as are known for example from DE 198 21 974 A I, are used for distance measurement using the incoherent optical transit time method (modulation interferometry method).
Bei einer Entfernungsmessung nach diesem optischen Laufzeitverfahren muss folgender Mischprozess durchgeführt werden:The following mixing process must be carried out for a distance measurement using this optical transit time method:
Das von der zu vermessenden Szene reflektierte amplitudenmodulierte Beleuchtungslicht wird mit einem Demodulationssignal, beispielsweise einem identischen Signal demoduliert (korreliert) und so die Phasenbeziehung (Korrelation) zwischen Sende- und Empfangssignal bestimmt. Diese Phasenbeziehung wird als Maß für die vom Sendelicht zurückgelegte Entfernung herangezogen.The amplitude-modulated illuminating light reflected by the scene to be measured is demodulated (correlated) with a demodulation signal, for example an identical signal, and the phase relationship (correlation) between the transmitted and received signal is thus determined. This phase relationship is used as a measure of the distance covered by the transmitted light.
Um ein komplettes 3D-Bild zu erhalten, ist es erforderlich die Szene mit einem zweidimensionalen Empfangsarray aufzunehmen, wobei jedes einzelne Pixel den oben beschriebenen Mischprozess durchführt. Fertigungstoleranzen, Temperaturschwankungen und Alterungsprozesse können dazu führen, dass die einzelnen Pixel im Empfangsarray in ihrer Funktion voneinander abweichen. Werden diese Abweichungen zu groß, ist es notwendig eine Referenzierung des Empfängerarrays vorzunehmen.In order to obtain a complete 3D image, it is necessary to record the scene with a two-dimensional receiving array, with each individual pixel performing the mixing process described above. Manufacturing tolerances, temperature fluctuations and aging processes can cause the individual pixels in the receiving array to differ in their function. If these deviations become too large, the receiver array must be referenced.
Aus der DE 101 26 086 AI ist ein optoelektronischer Sensor bekannt, bei dem zur Referenzierung des Licht von dem zur Beleuchtung der Szene verwendeten Sendeelement oder einem separaten Sendeelement auf ein Referenzobjekt innerhalb des Sensors gesendet und mittels einer separaten Empfängers oder der für den Empfang von Reflektionen aus der Szene vorgesehenen Empfängers das empfangene Signal vom Referenzobjekt als Referenzsignal erfasst und daraus Alterungs- und Temperatureffekte abgeleitet werden. Durch Amplitudenmodulation am Sender und einen Phasenkomparator am Empfänger wird auch bei diesem Sensor eine Entfernungsinformation abgeleitet. Aus der DE 196 43 287 A1 ist ein Verfahren und eine Anordnung bekannt, die es erlaubt, die folgenden Probleme beim optischen Laufzeitverfahren mit Bildaufnehmer und aktiver Beleuchtung zu minimieren: a) temperaturabhängige Phasenverschiebung des Empfangsarrays b) Temperaturdriften im Senderelement (LED bzw. Laserdiode) Bei diesem bekannten Verfahren wird eine Referenzierung des Sendesignals auf ein spezielles Referenzpixel im Empfangsarray vorgeschlagen, das bei jeder Messung ausschließlich ein Referenzsignal empfängt, das einen vorgegebenen Weg zurücklegt. Da die Laufzeit des Referenzsignals bekannt ist, können die verschiedenen Drifteffekte, die sich im Laufe der Zeit bei wechselnden Systembedingungen ändern, kompensiert werden.From DE 101 26 086 AI an optoelectronic sensor is known, in which, for referencing the light, is transmitted from the transmitter element used for illuminating the scene or a separate transmitter element to a reference object within the sensor and by means of a separate receiver or for receiving reflections the received signal from the reference object is acquired as a reference signal from the receiver provided in the scene and aging and temperature effects are derived therefrom. With this sensor, distance information is also derived from amplitude modulation at the transmitter and a phase comparator at the receiver. From DE 196 43 287 A1 a method and an arrangement are known which allow the following problems in the optical runtime method with image sensor and active lighting to be minimized: a) temperature-dependent phase shift of the receiving array b) temperature drifts in the transmitter element (LED or laser diode) In this known method, a referencing of the transmission signal to a special reference pixel in the reception array is proposed, which receives with each measurement only a reference signal that covers a predetermined path. Since the runtime of the reference signal is known, the various drift effects that change over time with changing system conditions can be compensated for.
Fertigungstoleranzen (z.B. Fixed Pattern Noise), Temperaturschwankungen und Alterungsprozesse führen dazu, dass die Kenngrößen der verschiedenen Pixel in einem Empfangsarray unterschiedlich stark voneinander abweichen. Werden diese Abweichungen zu groß, ist es notwendig eine Eichung des gesamten Empfängerarrays für jedes Pixel vorzunehmen. Dies ist mit dem oben genannten Verfahren nicht möglich. Andererseits hat man während des Betriebs des 3D Bildaufnehmers in der Regel keine Referenzszene zur Verfügung, mit der man diese Eichung für jedes Pixel aufgrund von bekannten Phasenbeziehungen realisieren kann.Manufacturing tolerances (e.g. fixed pattern noise), temperature fluctuations and aging processes mean that the parameters of the different pixels in a receiving array differ from one another to different degrees. If these deviations become too large, it is necessary to calibrate the entire receiver array for each pixel. This is not possible with the above procedure. On the other hand, during the operation of the 3D image sensor, there is generally no reference scene available with which this calibration can be carried out for each pixel based on known phase relationships.
Aufgabe der Erfindung ist es, ein Verfahren zur Referenzierung von 3D Bildaufnehmern anzugeben, mit denen eine Eichung des Empfangsarray während des Betriebs möglich ist.The object of the invention is to provide a method for referencing 3D image recorders with which calibration of the receiving array is possible during operation.
Diese Aufgabe wird durch ein Verfahren mit den Merkmalen der jeweils unabhängigen Ansprüche gelöst. Die vorteilhafte Ausgestaltung der Erfindung erfolgt gemäß den Merkmalen der abhängigen Ansprüche.This object is achieved by a method with the features of the respective independent claims. The advantageous embodiment of the invention is based on the features of the dependent claims.
Mit Hilfe der Erfindung ist es möglich die entfernungsspezifischen pixelindividuellen Unterschiede zu detektieren und mit geeigneten Mitteln zu kompensieren. Dazu wird das Empfangsarray ausschließlich mit einer Kalibrierstrahlung mit für alle Pixel zumindest weitgehend homogener Phasenlage zum Demodulationssignal von einer modulierbaren Lichtquelle (z.B. LED, Laserdiode, etc.) beleuchtet. Dies kann durch direkte oder durch Umlenkung erzielte Beleuchtung mit einer modulierbaren Lichtquelle mit annähernd gleichem Abstand zu allen Pixeln erreicht werden.With the aid of the invention, it is possible to detect the distance-specific pixel-specific differences and to compensate for them with suitable means. For this purpose, the receiving array is illuminated exclusively with calibration radiation with a phase position that is at least largely homogeneous for all pixels with respect to the demodulation signal from a modulatable light source (e.g. LED, laser diode, etc.). This can be achieved by direct lighting or by redirection of lighting with a modulatable light source with approximately the same distance from all pixels.
Die dabei auftretenden Empfängersignale der einzelnen Pixel werden pixelindividuell ausgewertet, d.h. Abweichungen, Störungen oder Defekte einzelner Pixel erkannt. Nur so kann eine Kompensation der pixelindividuellen Abweichungen erreicht werden, welche für die Erkennung und Verfolgung von Objekten in bewegten Systemen äußerst wichtig ist. Insbesondere kann neben oder anstelle eines Absolutwertvergleichs mit einem Sollwert auch die relative Phasenabweichung zwischen den Pixeln erfasst werden und so die Signale der Pixel auf eine Bezugsgröße normiert werden.The resulting receiver signals of the individual pixels are evaluated individually for each pixel, i.e. Deviations, disturbances or defects of individual pixels are recognized. This is the only way to compensate for pixel-specific deviations, which is extremely important for the detection and tracking of objects in moving systems. In particular, in addition to or instead of an absolute value comparison with a target value, the relative phase deviation between the pixels can also be recorded, and the signals of the pixels can thus be standardized to a reference variable.
Die Phasenbeziehung zwischen Sendesignal und Demodulationssignal wird dabei vorzugsweise geändert, was einer Messung mit einer virtuellen zweiten Entfernung entspricht, d.h. es erfolgt eine Kalibrierung auf zumindest zwei virtuelle Entfernungen. DieThe phase relationship between the transmission signal and the demodulation signal is preferably changed, which corresponds to a measurement with a virtual second distance, i.e. calibration is carried out over at least two virtual distances. The
Phasenlage wird vorzugsweise durch entsprechende Verzögerung am Sende- oder Demodulationssignal jeweils relativ zum anderen Signal bewirkt, so daß keine Änderung der tatsächlichen Entfernung zwischen Lichtquelle und Empfangsarray erfolgt.Phase position is preferably by a corresponding delay on the transmit or Demodulation signal causes relative to the other signal, so that there is no change in the actual distance between the light source and the receiving array.
Dadurch können insbesondere auch unabhängig von der tatsächlichen absoluten Phasenbeziehung für jede Kalibriermessung aus der Kenntnis der Phasenverschiebung zwischen den zumindest zwei Kalibriermessungen die pixelindividuellen Abweichungen relativ zueinander bewertet werden.As a result, the pixel-specific deviations relative to one another can in particular be evaluated independently of the actual absolute phase relationship for each calibration measurement from the knowledge of the phase shift between the at least two calibration measurements.
Die Phasenbeziehung ist vorzugsweise frei wählbar, wird beispielsweise entlang einer vorgegebenen Kennlinie über entsprechend viele Sendevorgänge durchgestimmt. So können Nichtlinearitäten in Abhängigkeit von der Entfernung späterer Zielobjekte pixelindividuell erkannt werden. Dies erlaubt dadurch eine Referenzierung bei unterschiedlichen virtuellen Entfernungen.The phase relationship is preferably freely selectable, for example, it is tuned along a predetermined characteristic curve over a corresponding number of transmission processes. In this way, nonlinearities can be detected individually on a pixel basis depending on the distance of later target objects. This allows referencing at different virtual distances.
Der 3D Bildaufnehmer nach der Erfindung weist in einem Ausführungsbeispiel der Erfindung zusätzlich zu den üblicherweise vorhandenen Elementen eine Referenzlichtquelle auf, die wie die Lichtquelle der Sendeeinheit modulierbar ist. Die Referenzlichtquelle ist so angebracht, dass das komplette Empfangsarray mit für alle Pixel zumindest weitgehend homogener Phasenlage zum Demodulationssignal und vorzugsweise auch in seiner Helligkeit annähernd homogen beleuchtet wird. D.h. es erfolgt eine direkte Beleuchtung ohne Verwendung von Referenzobjekten oder dergleichen. Bei optimaler Funktion des Empfängerarrays sollte jedes Pixel diejenige Entfernung bzw. Phasenverschiebung messen, die durch die Referenzstrecke und die eingestellten Phasenlage zwischen Referenzlichtquelle und Demodulationssignal vorgegeben wird.In one exemplary embodiment of the invention, the 3D image sensor according to the invention has, in addition to the elements which are usually present, a reference light source which, like the light source of the transmission unit, can be modulated. The reference light source is mounted in such a way that the complete receiving array is illuminated with an at least largely homogeneous phase position with respect to the demodulation signal for all pixels and preferably also approximately uniformly in terms of its brightness. That there is direct lighting without the use of reference objects or the like. If the receiver array functions optimally, each pixel should measure the distance or phase shift that is specified by the reference path and the set phase position between the reference light source and the demodulation signal.
Wenn einzelne Pixel aufgrund von Fertigungstoleranzen, Temperaturschwankungen und Alterungsprozesse gegenüber dem Sollwert oder relativ zueinander differieren, werden diese Abweichungen beispielsweise pixelindividuell in Form einer Look-up-Tabelle abgelegt. Dank der Phasenverschiebung können auch Nichtlinearitäten oder Störungen in bestimmten Entfernungsbereichen erkannt werden und diese z.B. in einer Matrix oder Kennlinienfeldern abgelegt werden. Darüber hinaus ist es denkbar Interpolationen zwischen zwei Stützpunkten durchzuführen. Eine zweite Ausführungsform der Erfindung sieht vor zur Kalibrierung des gesamten Empfängerarrays das Beleuchtungslicht der Sendeeinheit so umzuleiten, dass eine interne Verbindung zwischen Sender und E pfängerarray entsteht. Gleichzeitig wird in diesem Fall die externe Verbindung über die Beleuchtung der Szene unterbrochen, damit kein Sendelicht über den Umweg einer unbekannten Szenerie und dadurch mit einer unbekannten Phasenverschiebung auf die Pixel fäJJt. Während der Entfernungsmessung wird gewährleistet, dass die interne Verbindung wieder unterbrochen ist, um eine Störung der Phasenmessung zu vermeiden. Diese Schließvorrichtungen sind z.B. durch einen oder mehrere mechanische Umschalter ausgestaltet. In der Praxis wird jedoch versucht, so weit wie möglich auf bewegliche Komponenten zu verzichten. Auch in diesem Fall wird die Phasenbeziehung zwischen moduliertem Sendesignal und Empfängersignal variiert, um eine Kalibrierung bei unterschiedlichen Phasenlagen (virtuelle Entfernungen) durchzuführen.If individual pixels differ from the target value or relative to one another due to manufacturing tolerances, temperature fluctuations and aging processes, these deviations are stored, for example, pixel-specifically in the form of a look-up table. Thanks to the phase shift, non-linearities or disturbances in certain distance ranges can also be detected and these can be stored, for example, in a matrix or characteristic fields. In addition, it is conceivable to carry out interpolations between two support points. A second embodiment of the invention provides for the calibration of the entire receiver array to redirect the illuminating light of the transmitter unit so that an internal connection between the transmitter and receiver array is created. At the same time, the external connection via the lighting of the scene is interrupted in this case, so that no transmitted light detours through an unknown scene and thus with an unknown phase shift to the pixels. During the distance measurement, it is ensured that the internal connection is broken again in order to avoid a disturbance in the phase measurement. These locking devices are configured, for example, by one or more mechanical changeover switches. In practice, however, attempts are made to avoid moving components as much as possible. In this case too, the phase relationship between the modulated transmission signal and the receiver signal is varied in order to carry out a calibration in the case of different phase positions (virtual distances).
Ein Nachteil der herkömmlichen Referenzmessung, bei der eine bekannte Szene aufgenommen werden muss, besteht darin, dass nicht immer eine solche Szene zur Verfügung steht, z.B. wenn die Referenzszene verdeckt wird. Durch die oben beschriebene Erfindung wird dieses Problem umgangen. Ein weiterer Vorteil der erfindungsgemäßen Referenztechnik ist die Möglichkeit, eine Referenzierung über den kompletten Temperaturbereich des 3D Bildaufnehmers durchzuführen, ohne ihn von seinem Einbauort zu entfernen. Ebenso verhält es sich bei altersbedingten Driften. A disadvantage of the conventional reference measurement, in which a known scene has to be recorded, is that such a scene is not always available, e.g. if the reference scene is covered. This problem is avoided by the invention described above. Another advantage of the reference technology according to the invention is the possibility of referencing over the entire temperature range of the 3D image sensor without removing it from its installation location. It is the same with age-related drifts.

Claims

Patentansprüche claims
1. Verfahren zur Kalibrierung von 3D - Bildaufnehmern, welche aufweisen:1. Method for calibrating 3D image recorders, which have:
- eine Lichtquelle, die ein moduliertes Sendesignal in die betrachtete Szene abstrahlt, unda light source which emits a modulated transmission signal into the scene under consideration, and
- ein Empfangsarray aus einer Mehrzahl von Pixeln, welche aus einem Demodulationssignal mit vorgegebener Phasenlage zum Sendesignal und der von der Szene reflektierten, detektierten Strahlung jeweils pixelbezogen ein Empfängersignal erzeugen, welches als Maß für die Entfernung herangezogen wird, dadurch gekennzeichnet, dass- A receiving array of a plurality of pixels, each of which generates a receiver signal, which is used as a measure of the distance, from a demodulation signal with a predetermined phase position with respect to the transmission signal and the radiation detected and reflected by the scene, characterized in that
- zur Kalibrierung das komplette Empfangsarray ausschließlich mit einer Kalibrierstrahlung mit für alle Pixel zumindest weitgehend homogener Phasenlage zum Demodulationssignal beleuchtet wird und die dabei auftretenden Empfängersignale der einzelnen Pixel ausgewertet werden.- For calibration, the entire receiving array is illuminated exclusively with calibration radiation with a phase position that is at least largely homogeneous with respect to the demodulation signal for all pixels, and the receiver signals of the individual pixels that occur are evaluated.
2. Verfahren nach Anspruch 1, dadurch gekennzeichnet, dass die relative Phasenabweichung zwischen den Pixeln erfasst wird.2. The method according to claim 1, characterized in that the relative phase deviation between the pixels is detected.
3. Verfahren nach Anspruch 1 oder 2, dadurch gekennzeichnet, dass zumindest eine zweite Messung mit einer Kalibrierstrahlung erfolgt mit einer zweiten, von der ersten abweichenden Phasenlage zwischen Kalibrierstrahlung und Demodulationssignal.3. The method according to claim 1 or 2, characterized in that at least one second measurement with a calibration radiation is carried out with a second, different from the first phase position between the calibration radiation and demodulation signal.
4. Verfahren nach Anspruch 3, dadurch gekennzeichnet, dass die Phasenbeziehung frei wählbar ist, vorzugsweise entlang einer vorgegebenen Kennlinie über entsprechend viele Sendevorgänge durchgestimmt wird.4. The method according to claim 3, characterized in that the phase relationship is freely selectable, is preferably tuned along a predetermined characteristic over a corresponding number of transmission processes.
5. Verfahren nach einem der Ansprüche 1 bis 4, dadurch gekennzeichnet, dass für die Erzeugung der Kalibrierstrahlung eine weitere Lichtquelle verwendet wird, welche das komplette Empfangsarray zu definierten Zeiten ausschließlich beleuchtet.5. The method according to any one of claims 1 to 4, characterized in that a further light source is used to generate the calibration radiation, which only illuminates the entire receiving array at defined times.
6. Verfahren nach einem der Ansprüche 1 bis 5, dadurch gekennzeichnet, dass für die Erzeugung der Kalibrierstrahlung die bereits vorhandene Lichtquelle verwendet wird, wobei die Strahlung von der Lichtquelle auf das Empfangsarray umgeleitet und die für die Beleuchtung der Szene vorgesehene externe Verbindung unterbrochen wird.6. The method according to any one of claims 1 to 5, characterized in that the already existing light source is used for generating the calibration radiation, wherein the radiation is redirected from the light source to the receiving array and the external connection provided for illuminating the scene is interrupted.
7. Verfahren nach einem der vorangehenden Ansprüche, dadurch gekennzeichnet, dass die zu den definierten Zeiten ermittelte pixelindividuelle Phasenabweichung pixelindividuell in Form einer Look-up-Tabelle zur Korrektur der 3D Bildinformation der betrachteten Szenen abgelegt wird.7. The method according to any one of the preceding claims, characterized in that the pixel-specific phase deviation determined at the defined times is stored pixel-individually in the form of a look-up table for correcting the 3D image information of the scenes under consideration.
8. Verwendung des Verfahrens nach einem der vorangehenden Ansprüche für 3D- Bildaufnehmer zur Umfeld- und Innenraumsensierung bei Kraftfahrzeugen, insbesondere zur Hindernis- und/oder Fahrspurerkennung bei einem Kraftfahrzeug und/oder Sitzbelegungserkennung.8. Use of the method according to one of the preceding claims for 3D image recorders for environment and interior sensing in motor vehicles, in particular for obstacle and / or lane detection in a motor vehicle and / or seat occupancy detection.
9. Verwendung des Verfahrens nach einem der vorangehenden Ansprüche 1 bis 7 für 3D- Bildaufnehmer zur Sensierung bei industriellen Anlagen. 9. Use of the method according to one of the preceding claims 1 to 7 for 3D image sensors for sensing in industrial plants.
EP03799433A 2002-12-18 2003-12-18 Method for calibrating 3d image sensors Ceased EP1573356A1 (en)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
DE10259135 2002-12-18
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US20060228050A1 (en) 2006-10-12

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