Optical measurement system and optical measurement method

Abstract

The optical measurement system includes a first optical transceiver including a first light source, a first camera, a second camera, and a first beam splitter, and a second optical transceiver including a second light source, a third camera, a fourth camera, and a second beam splitter. The optical measurement system operates in at least one operating mode, including a first operating mode, in which the first camera and the third camera are utilized to determine a three-dimensional shape of the environment using a triangulation technique, and at least one of the second camera and the fourth camera is utilized to determine the three-dimensional shape of the environment using a time-of-flight technique.

Description

[Technical Field]

[0001] One aspect of the present disclosure relates to an optical measurement system for navigation in a three-dimensional environment by providing a reliable three-dimensional image of the environment.

[0002] In particular, one aspect of the present disclosure relates to optical three-dimensional imaging of scenes with an extreme dynamic range of background illumination, ranging from starlit night to sun-filled day. [Background technology]

[0003] Our world is three-dimensional, and therefore, artificial devices that need to navigate in this world need to know their location in the three-dimensional environment. To this end, 3D cameras have been invented that utilize a variety of physical phenomena, including active 3D imaging techniques such as radar, ultrasound, or optical time-of-flight imaging, or passive 3D imaging techniques such as triangulation, particularly a form of stereoscopic vision. In the animal kingdom, most organisms use passive triangulation for navigation, often utilizing two cameras (eyes) for stereoscopic vision, or sometimes even three or more eyes for multi-camera triangulation.

[0004] Optical range cameras are particularly interesting due to their potential for implementation in a compact, economical form factor with a powerful solid-state light source and image sensor. However, optical range cameras used in uncontrolled outdoor environments face the challenge of extreme variations in background illumination. Full daylight corresponds to an illuminance of approximately 100,000 lux, while moonless starlight under a clear sky corresponds to an illuminance of approximately 0.001 lux. Therefore, optical range cameras used for outdoor navigation must cope with a dynamic range of background illumination of at least eight orders of magnitude.

[0005] In addition to this problem of extreme dynamic range of background illumination, various optical 3D measurement techniques have inherent drawbacks.

[0006]

[0006] Passive triangulation requires a sufficient amount of scene luminance for features in a scene to be visible by the image sensor used and available for stereoscopic viewing. This problem can be solved by illuminating the scene with artificial light in all situations where natural background illumination is insufficient. A severe drawback of triangulation is its reliance on the unique features of various objects, which are essential for determining the distance to each feature. Features are invisible on bare walls, white coverings, and flat surfaces, and therefore triangulation does not work. Such unstructured surfaces are common in artificial environments, and for this reason, triangulation 3D imaging is not suitable for all parts of a scene where such flat surfaces are present. In cases where background illumination is not too high, this problem can be overcome by providing structured illumination of the scene, thereby creating the necessary features on the surfaces of flat objects.

[0007]

[0007] For optical time-of-flight (TOF) 3D measurement techniques, it is necessary to determine, at each pixel location, the arrival time of a light pulse or the phase delay of a modulated waveform emitted by a light source in a range camera. These measurements can be made reliably if the reflecting surface does not have excessive height variations. Unfortunately, this condition is often violated at object boundaries, where the object reflects part of the modulated light and the background reflects another part of the modulated light, resulting in erroneous phase delay or arrival time measurements. These so-called multipath errors also occur with partially reflective surfaces, so that two or more objects, each at their own distance to the camera, can contribute to the total reflected signal. Such multipath errors can be eliminated by utilizing special measurement techniques, such as FMCW (frequency-modulated continuous wave) lidar. However, this requires the acquisition of a large amount of additional backreflection information, adding considerable complexity to the imaging and data processing tasks. Summary of the Invention [Problem to be solved by the invention]

[0008]

[0008] An object of one aspect of the present disclosure is to address the aforementioned problems of extreme dynamic range in background illumination, the inability to determine distance data to unstructured surfaces by triangulation, and erroneous distance measurements of TOF techniques due to multipath effects, by providing an optical range camera whose components collectively contribute to solving all of the aforementioned problems depending on the level of background illumination. [Means for solving the problem]

[0009]

[0009] An optical range camera according to one aspect of the present disclosure comprises two or more transceiver modules. Each transceiver comprises a light source whose intensity can be temporally modulated, a beam splitter that directs reflected light to a first camera and a second camera, and an electronic control system for acquiring and processing signals from the first camera and the second camera. The first camera acquires an intensity or color image of a scene in a field of view in the wavelength range of the background light and the light source. The second camera comprises pixels, each capable of sensing and demodulating incident modulated light reflected back from objects in the scene.

[0010] Under high illuminance conditions, such as in full daylight, a first camera of two or more transceiver modules is utilized to determine the three-dimensional shape of the environment using known triangulation techniques. Under moderate illuminance conditions, both the triangulation camera and the time-of-flight three-dimensional camera of the transceiver are utilized. Under low illuminance conditions, such as at night, a second camera of each transceiver is utilized to determine the three-dimensional shape of the environment using known time-of-flight techniques. Under conditions with wide illumination differences, such as driving a vehicle out of a tunnel into full daylight, a first camera of a transceiver module is utilized to determine the three-dimensional shape of brightly lit portions of the scene using triangulation, and a second camera is utilized to determine the three-dimensional shape of weakly lit portions of the scene using time-of-flight techniques.

[0011] This combination of triangulation and TOF techniques for distance measurement also overcomes the problems of triangulation with unstructured surfaces and the problems of TOF techniques with multipath imaging: in those parts of the scene where unstructured surfaces are present, the results of the TOF imaging camera are utilized, and at multiple object boundaries, the TOF results are discarded and the triangulation results, which work best for the high contrast situations that often occur at multiple object boundaries, are utilized.

[0012]

[0012] In this manner, the DC (direct current) portion of the modulated light source is utilized in triangulation, while the AC (alternating current) portion of the modulated light source is demodulated and utilized in one of the known TOF imaging techniques.

[0013]

[0013] An optical measurement system according to one aspect of the present disclosure includes a first optical transceiver including a first light source that emits light modulated at a frequency greater than 100 kHz, a first camera that acquires an intensity or color image, a second camera that can sense and demodulate the light emitted from the first light source and reflected by an object, and a first beam splitter that separates the reflected light and directs it to the first camera and the second camera; and a second optical transceiver including a second light source that emits light modulated at a frequency greater than 100 kHz, a third camera that acquires an intensity or color image, a fourth camera that can sense and demodulate the modulated light emitted from the second light source and reflected by an object, and a second beam splitter that separates the reflected light and directs it to the third camera and the fourth camera. The optical measurement system operates in at least one operating mode, including a first operating mode, in which the first camera and the third camera are utilized to determine the three-dimensional shape of the environment using triangulation techniques, and at least one of the second camera and the fourth camera is utilized to determine the three-dimensional shape of the environment using time-of-flight techniques.

[0014]

[0014] At least one operating mode may include a second operating mode, in which the first camera and the third camera may be utilized to determine the three-dimensional shape of the environment using triangulation techniques, and the second camera and the fourth camera may not be utilized to determine the three-dimensional shape of the environment.

[0015]

[0015] At least one operating mode may include a third operating mode, in which the first camera and the third camera may not be utilized to determine the three-dimensional shape of the environment, and at least one of the second camera and the fourth camera may be utilized to determine the three-dimensional shape of the environment using time-of-flight techniques.

[0016] In at least one of the at least one operating mode, both the first light source and the second light source can emit light toward the object.

[0017]

[0017] When using time-of-flight techniques, both the second camera and the fourth camera may be utilized to determine the three-dimensional shape of the environment using time-of-flight techniques.

[0018]

[0018] Under a first condition (medium illumination condition), the optical measurement system can operate in a first operating mode, and under a second condition (high illumination condition) in which the background illumination is higher than the background illumination of the first condition, the optical measurement system can operate in a second operating mode.

[0019]

[0019] Under a first condition (medium illumination condition), the optical measurement system can operate in a first operating mode, and under a third condition (low illumination condition) in which the background illumination is lower than the background illumination of the first condition, the optical measurement system can operate in a third operating mode.

[0020] In a first mode of operation (under low or no illumination conditions), the first camera and the third camera may be utilized to determine the three-dimensional shape of a first portion of the environment using triangulation techniques, and at least one of the second camera and the fourth camera may be utilized to determine the three-dimensional shape of a second portion of the environment using time-of-flight techniques, the second portion being less illuminated than the first portion, i.e., the first portion being a brightly illuminated portion and the second portion being a weakly illuminated portion.

[0021]

[0021] In a first operating mode, the DC portion of the modulated light may be utilized for the triangulation technique, while the AC portion of the modulated light may be demodulated and utilized for the time-of-flight technique.

[0022]

[0022] Each of the first light source and the second light source may include a laser having red, green, and blue wavelengths, respectively. Alternatively, each of the first light source and the second light source may include a white LED (light emitting diode).

[0023] Each of the first and third cameras may include a color filter, an imaging lens, and a black and white or color image sensor.

[0024]

[0024] Each of the second and fourth cameras may include a color filter, an imaging lens, and a demodulation image sensor.

[0025] An optical measurement method according to one aspect of the present disclosure uses an optical measurement system that includes a first optical transceiver including a first light source that emits light modulated at a frequency greater than 100 kHz, a first camera that acquires an intensity or color image, a second camera that can sense and demodulate the light emitted from the first light source and reflected by an object, and a first beam splitter that separates and directs the reflected light to the first and second cameras, and a second optical transceiver that includes a second light source that emits light modulated at a frequency greater than 100 kHz, a third camera that acquires an intensity or color image, a fourth camera that can sense and demodulate the modulated light emitted from the second light source and reflected by an object, and a second beam splitter that separates and directs the reflected light to the third and fourth cameras. The optical measurement method includes operating the optical measurement system in a first operating mode, in which the first camera and the third camera are utilized to determine the three-dimensional shape of the environment using triangulation techniques, and at least one of the second camera and the fourth camera is utilized to determine the three-dimensional shape of the environment using time-of-flight techniques.

[0026]

[0026] Only one of the first light source and the second light source may be provided. Only one of the second camera and the fourth camera may be provided. That is, an optical measurement system according to another aspect of the present disclosure includes a light source that emits light modulated at a frequency greater than 100 kHz, a first camera that acquires intensity or color images, a second camera that can sense and demodulate light emitted from the first light source and reflected by an object, and a first optical transceiver that includes a first beam splitter that separates and directs the reflected light to the first camera and the second camera, and a second optical transceiver that includes a third camera that acquires intensity or color images. The optical measurement system operates in at least one operating mode, including a first operating mode, in which the first camera and the third camera are utilized to determine the three-dimensional shape of the environment using a triangulation technique, and the second camera is utilized to determine the three-dimensional shape of the environment using a time-of-flight technique.

[0027]

[0027] One aspect of the present disclosure will be better understood, and objects other than those set forth above will become apparent, in consideration of the following detailed description, which refers to the accompanying drawings. [Brief explanation of the drawings]

[0028] [Figure 1] FIG. 1 shows the schematic architecture of an optical transceiver consisting of a modulated light source, a first imaging system used in triangulation, and a second imaging system used in TOF demodulation, all under the control of an electronic processing unit. [Figure 2] FIG. 1 illustrates one embodiment of an optical range camera consisting of two transceivers separated by a triangulation base D. DETAILED DESCRIPTION OF THE INVENTION

[0029]

[0028] The main objective of one aspect of the present disclosure is to provide an optical distance camera that provides high dynamic range operation so that the distance camera can be used in all situations where background illumination is not controlled.

[0030]

[0029] A further object of one aspect of the present disclosure is to provide an optical range camera that, when used outdoors, can produce reliable range images covering a wide range of natural illumination, from full daylight to starlit night.

[0031]

[0030] Another object of one aspect of the present disclosure is to provide an optical range camera that overcomes the main problem of stereoscopic techniques, namely, the inability to determine the distance to objects with unstructured surfaces, and the main problem of time-of-flight techniques, namely, inaccurate range readings due to saturation of the time-of-arrival image sensor and multipath reflected signals.

[0032] The basic element of the optical range camera according to this example is a transceiver, shown schematically in FIG. 1. The transceiver is housed in a transceiver casing 1. A central processing unit 2 controls all subunits housed in the transceiver. The processing unit 2 modulates a solid-state light source 3, emitting light at a sufficiently high modulation frequency, typically above 100 kHz, utilized in any of the known TOF distance measurement techniques. The modulated light is reflected by an object surface 4 and enters the transceiver through a front window 5. A beam splitter 6 separates the incoming back-reflected light into two portions and directs the incoming light to one of the two camera subsystems. The two portions need not be of equal proportion. Rather, it may be preferable for the camera subsystem used for triangulation to receive proportionally less light, while the TOF camera subsystem receives proportionally more light.

[0033] The first camera used in triangulation range imaging consists of a color filter 7, an imaging lens 8, and a high-resolution black-and-white or color image sensor 9. A central processing unit 2 controls the image acquisition process of the image sensor 9 via an electronic interface 10 and synchronizes it with the other components of the range camera system according to this example. The color filter 7 is used to transmit only light of the desired wavelength from the object surface 4 to the image sensor 9. Infrared wavelengths are undesirable due to their large penetration depth into the image sensor 9, which can cause blurry images and reduce the effectiveness of the feature extraction triangulation algorithm. Shorter wavelengths, reaching the ultraviolet, can be undesirable due to the damage that high-energy wavelength light can cause to the image sensor 9.

[0034] The second camera used in TOF-based distance imaging consists of a color filter 11, an imaging lens 12, and a demodulation image sensor 13. The central processing unit 2 controls the image acquisition process of the image sensor 13 via an electronic interface 14, synchronizing it with other components of the distance camera system, and in particular synchronizing the demodulation function of the image sensor 13 with the modulation of the light source 3. The color filter 11 is used to transmit only light of the desired wavelength from the object surface 4 to the demodulation image sensor 13. In particular, the color filter 11 is used to block background light arising not from the modulated light source 3 but rather from natural or artificial light sources in the scene. This is possible because the modulated light source 3 is often a solid-state device whose wavelength spectrum exhibits peaks that can be preferentially passed to the demodulation image sensor 13. As an example, consider a modulated light source 3 consisting of a laser with three different monochromatic wavelengths—red, green, and blue—in proportions such that the emitted modulated light appears white to the human eye. In this case, it is advantageous for the color filter 11 to block all but one or some of the laser's three monochromatic wavelength peaks. Alternatively, consider a modulated light source consisting of a white LED. The white appearance of the LED is achieved by coating a blue LED with a phosphor layer, which converts much of the blue light into longer wavelength light, giving the human eye an overall color impression of "white." Nevertheless, the wavelength spectrum of such a white LED exhibits a blue peak. In this case, it is advantageous for the color filter 11 to block all wavelengths except the blue peak in the white LED's wavelength spectrum.

[0035] The range camera according to this example consists of two or more transceivers as shown in Figure 1. The simplest configuration of two transceivers is shown in Figure 2. A first transceiver 20 with a modulated light source 21 is laterally displaced by a triangulation base distance 24 from a second transceiver 22 with a modulated light source 23. Modulated light from light sources 21 and 23 is emitted toward an object surface 25, from which it is reflected back into the camera subsystems of transceivers 20 and 22. Light emitted from a point on object surface 25 will travel along direction 26 into first transceiver 20 and along direction 27 into second transceiver 22. The angle 28 between directions 26 and 27 is known as the triangulation angle α.

[0036]

[0035] That is, in this example, the system includes a first transceiver 20 and a second transceiver 22. As described above with reference to Figure 1, each of the first transceiver 20 and the second transceiver 22 can be configured as shown in Figure 1. The first transceiver 20 includes a light source 3 (first light source), a camera (first camera) consisting of a color filter 7, an imaging lens 8, and an image sensor 9, a camera (second camera) consisting of a color filter 11, an imaging lens 12, and a demodulation image sensor 13, and a beam splitter 6 (first beam splitter). The second transceiver 22 includes a light source 3 (second light source), a camera (third camera) consisting of a color filter 7, an imaging lens 8, and an image sensor 9, a camera (fourth camera) consisting of a color filter 11, an imaging lens 12, and a demodulation image sensor 13, and a beam splitter 6 (second beam splitter).

[0037] When more than two transceivers are utilized to implement a range camera, each pair of transceivers can be considered a stereo pair as shown in FIG.

[0038] The range camera according to this example achieves a large dynamic range with respect to background illumination levels through three modes of operation.

[0039] (1) A number of transceivers with a mutual triangulation angle α are used to create a 3D image of the environment according to known triangulation methods when the background illumination level is so high that the demodulation image sensor 13 saturates and is unable to reliably measure the phase delay or time of arrival of the modulated light, which typically occurs when a range camera is operated outdoors in full daylight.

[0040] (2) When the background illumination is moderate, i.e., when the demodulation image sensor 13 is not saturated, both camera subsystems of each transceiver can be used to acquire a 3D image. Many transceivers with a mutual triangulation angle α are used to create a 3D image of the environment according to known methods of triangulation and stereopsis. Each TOF camera of each transceiver is used to create a 3D image of the environment according to known methods of time-of-flight imaging. Several transceivers can be positioned on the same device or within the field of view of this device and operate simultaneously. For this reason, a TOF imaging technique must be used that allows the simultaneous operation of several TOF cameras with minimal mutual interference, as described, for example, by B. Buttgen et al. in "Pseudonoise Optical Modulation for Real-Time 3-D Imaging With Minimum Interference," IEEE Transactions on Circuits and Systems 1, Vol. 54, No. 10, October 2007. In this way, the DC portion of Light Source 3 is utilized to illuminate portions of the scene where little natural light is available, thereby improving the performance of the triangulation subsystem, while the AC portion of Light Source 3 is utilized to implement the modulation / demodulation scheme required by the TOF subsystem. This case of moderate background illumination, with both range camera subsystems operating simultaneously, allows for the fusion of range information from both range camera subsystems, overcoming the shortcomings of each specific 3D imaging technique. Unstructured object surfaces illuminated by unstructured natural or artificial light do not provide the local features required for triangulation and stereoscopic techniques. As a result, in those portions of the scene where no distinguishable features exist, only the range information provided by the TOF camera subsystem is utilized. Conversely, most TOF imaging techniques suffer from the multipath problem, where each TOF pixel receives modulated light from various distances, thereby violating the mathematical assumptions of TOF 3D signal extraction methods.Multipath reflections often occur at object boundaries, and these boundaries provide regions of strong character where triangulation techniques work particularly well. For this reason, in those parts of the scene where multiple object boundaries exist, only the distance information provided by the triangulation camera subsystem is utilized.

[0041] (3) When there is very little back-reflected light from target objects in the scene, such that the triangulation sensor 9 cannot generate a sufficient signal-to-noise ratio for reliable triangulation, only the TOF cameras of the various transceivers are utilized. A typical situation in which this occurs is nighttime operation of the range camera, which involves imaging objects that are so far away that the light sources 3 do not provide sufficient illumination for the triangulation sensor 9. In this case, there may be additional light sources in the field of view of the range camera, such as headlights of oncoming vehicles, street lights, or light sources in or on buildings. These light sources are of limited geometric range and provide image data with high local contrast. Therefore, their image data can be utilized by the triangulation subsystem for reliable range imaging in all parts of the scene where such additional light sources are present.

[0042]

[0041] That is, the system can operate in a first operation mode, a second operation mode, and a third operation mode. The central processing unit 2 (controller) can operate the system in three operation modes. In other words, the controller can switch the operation mode among the three operation modes. As described above, the operation mode may be switched based on the detection results of the image sensor 9 (first and third cameras) and the image sensor 13 (second and fourth cameras). The first operation mode corresponds to the above case (2). In the first operation mode, the first camera and the third camera are used to determine the three-dimensional shape of the environment using the triangulation technique, and the second camera and the fourth camera are used to determine the three-dimensional shape of the environment using the TOF technique. The second operation mode corresponds to the above case (1). In the second operation mode, the first camera and the third camera are used to determine the three-dimensional shape of the environment using the triangulation technique, and the second camera and the fourth camera are not used to determine the three-dimensional shape of the environment. The third operating mode corresponds to the above-mentioned case (3). In the third operating mode, the first camera and the third camera are not used to determine the three-dimensional shape of the environment, and the second camera and the fourth camera are used to determine the three-dimensional shape of the environment using the TOF technique. The system operates in the first operating mode under a first condition where the background illumination is medium. The system operates in the second operating mode under a second condition where the background illumination is higher than the background illumination of the first condition. The system operates in the third operating mode under a third condition where the background illumination is lower than the background illumination of the first condition. In all three operating modes, both the light source 3 of the first transceiver and the light source 3 of the second transceiver emit light toward the object surface 4.

[0043] In summary, there are three operating regimes for the range camera according to this example, in which the information from the two camera subsystems of each transceiver is combined in different ways.

[0044] (1) In the case of high background illumination, only the 3D image from the triangulation subsystem is utilized.

[0045] (2) For moderate background illumination, both triangulation and TOF 3D images are utilized, with one modality being used exclusively in image areas where one of the 3D imaging techniques has weaknesses. In portions of the scene with weak or no features, TOF 3D data is preferably used, and in portions of the scene containing multiple object boundaries, triangulation data is preferably used.

[0046] (3) When background illumination is low or absent, TOF 3D data is primarily used, except for parts of the scene containing light sources where distances are preferably determined by triangulation.

[0047] Although an example of the present disclosure has been described above, the present disclosure is not limited to the above example. The system may operate only in the first operation mode. The system may not operate in the second or third operation modes. In the first operation mode, at least one of the second camera and the fourth camera may be used to determine the three-dimensional shape of the environment using a TOF technique, and any one of the second camera and the fourth camera may not be used to determine the three-dimensional shape of the environment.

[0048]

[0047] One aspect of the present disclosure is a device and method for reliable measurement of distance images in applications with a high dynamic range of background illumination, consisting of two or more optical transceivers, each transceiver including a light source whose intensity can be temporally modulated at a high frequency exceeding 100 kHz, a beam splitter that allows two camera systems to view the scene simultaneously, a first camera that acquires intensity or color images, and a second camera that can sense and demodulate back-reflected light resulting from the modulated light source, such that under high illumination conditions, a triangulation 3D imaging method is utilized, under medium illumination conditions, both a triangulation 3D imaging method and a time-of-flight 3D imaging method are utilized, and under low or no illumination conditions, a time-of-flight 3D imaging method is utilized, with the triangulation 3D imaging method being used locally relative to the light source in the field of view.

[0049] One aspect of the present disclosure is an optical range camera with extremely high dynamic range with respect to background illumination levels, consisting of two or more transceiver modules. Each transceiver consists of a light source whose intensity can be temporally modulated, a beam splitter that directs reflected light to a first camera and a second camera, and an electronic control system for acquiring and processing signals from the first camera and the second camera. The first camera acquires an intensity or color image of a scene in its field of view in the wavelength range of the natural background light and the light source. The image sensor of the second camera includes pixels that can each sense and demodulate incident modulated light back-reflected from objects in the scene.

[0050] Under high light conditions, such as in full daylight, a first camera of two or more transceiver modules is utilized to determine the three-dimensional shape of the environment using known triangulation techniques. Under medium light conditions, both the triangulation camera and the time-of-flight three-dimensional camera of the transceiver are utilized. Under low light conditions, such as at night, a second camera of each transceiver is utilized to determine the three-dimensional shape of the environment using known time-of-flight techniques. Under conditions with wide illumination differences, such as driving a vehicle out of a tunnel into full daylight, a first camera of a transceiver module is utilized to determine the three-dimensional shape of brightly lit portions of the scene using triangulation, and a second camera is utilized to determine the three-dimensional shape of weakly lit portions of the scene using time-of-flight techniques.

Claims

1. a first optical transceiver including a first light source that emits light modulated at a frequency greater than 100 kHz, a first camera that acquires an intensity or color image, a second camera that can sense and demodulate the light emitted from the first light source and reflected by an object, and a first beam splitter that separates and directs the reflected light to the first camera and the second camera; a second optical transceiver including a second light source that emits light modulated at a frequency greater than 100 kHz, a third camera that acquires an intensity or color image, a fourth camera that can sense and demodulate the modulated light emitted from the second light source and reflected by the object, and a second beam splitter that separates and directs the reflected light to the third camera and the fourth camera; An optical measurement system comprising: The optical measurement system operates in at least one operating mode including a first operating mode, wherein in the first operating mode, the first camera and the third camera are utilized to determine a three-dimensional shape of an environment using a triangulation technique, and at least one of the second camera and the fourth camera is utilized to determine the three-dimensional shape of the environment using a time-of-flight technique.

2. 2. The optical measurement system of claim 1, wherein the at least one operational mode includes a second operational mode, in which the first camera and the third camera are utilized to determine the three-dimensional shape of the environment using the triangulation technique, and the second camera and the fourth camera are not utilized to determine the three-dimensional shape of the environment.

3. 3. The optical measurement system of claim 1, wherein the at least one operating mode includes a third operating mode, in which the first camera and the third camera are not utilized to determine the three-dimensional shape of the environment, and at least one of the second camera and the fourth camera is utilized to determine the three-dimensional shape of the environment using the time-of-flight technique.

4. 4. The optical measurement system of claim 1, wherein in at least one of the at least one operating mode, both the first light source and the second light source emit light towards the object.

5. 5. The optical measurement system of claim 1, wherein when using the time-of-flight technique, both the second camera and the fourth camera are utilized to determine the three-dimensional shape of the environment using the time-of-flight technique.

6. 3. The optical measurement system of claim 2, wherein under a first condition, the optical measurement system operates in the first operating mode, and under a second condition in which background illumination is higher than the background illumination of the first condition, the optical measurement system operates in the second operating mode.

7. 4. The optical measurement system of claim 3, wherein under a first condition, the optical measurement system operates in the first operating mode, and under a third condition in which background illumination is lower than the background illumination of the first condition, the optical measurement system operates in the third operating mode.

8. 8. The optical measurement system of claim 1, wherein in the first mode of operation, the first camera and the third camera are utilized to determine the three-dimensional shape of a first portion of the environment using the triangulation technique, and the at least one of the second camera and the fourth camera is utilized to determine the three-dimensional shape of a second portion of the environment using the time-of-flight technique, the second portion being less brightly illuminated than the first portion.

9. 9. The optical measurement system of claim 1, wherein in the first mode of operation, a DC portion of the modulated light is utilized for the triangulation technique, while an AC portion of the modulated light is demodulated and utilized for the time-of-flight technique.

10. 10. The optical measurement system of claim 1, wherein the first light source and the second light source each include a laser having red, green, and blue wavelengths, respectively.

11. The optical measurement system of any one of claims 1 to 9, wherein the first light source and the second light source each comprise a white light emitting diode.

12. The optical measurement system of any one of claims 1 to 11, wherein the first camera and the third camera each include a color filter, an imaging lens, and a black and white or color image sensor.

13. The optical measurement system of any one of claims 1 to 12, wherein the second camera and the fourth camera each include a color filter, an imaging lens, and a demodulation image sensor.

14. 1. An optical measurement method using an optical measurement system, the optical measurement system comprising: a first optical transceiver including a first light source that emits light modulated at a frequency greater than 100 kHz, a first camera that acquires an intensity or color image, a second camera that can sense and demodulate the light emitted from the first light source and reflected by an object, and a first beam splitter that separates and directs the reflected light to the first camera and the second camera; a second optical transceiver including a second light source that emits light modulated at a frequency greater than 100 kHz, a third camera that acquires an intensity or color image, a fourth camera that can sense and demodulate the modulated light emitted from the second light source and reflected by the object, and a second beam splitter that separates and directs the reflected light to the third camera and the fourth camera; Equipped with 1. The optical measurement method, comprising: operating the optical measurement system in a first mode of operation, wherein the first camera and the third camera are utilized to determine a three-dimensional shape of an environment using a triangulation technique, and at least one of the second camera and the fourth camera is utilized to determine the three-dimensional shape of the environment using a time-of-flight technique.

Images