WO2023077412A1

WO2023077412A1 - Object distance measurement method and device

Info

Publication number: WO2023077412A1
Application number: PCT/CN2021/128943
Authority: WO
Inventors: 罗鹏飞; 唐样洋
Original assignee: 华为技术有限公司
Priority date: 2021-11-05
Filing date: 2021-11-05
Publication date: 2023-05-11
Also published as: CN117480408A

Abstract

An object distance measurement method and device. The method comprises: acquiring a first image and a first phase map corresponding to the first image by using a time of flight (ToF) sensor (4033) (601); recognizing a target area corresponding to a target object in the first image, and determining, on the basis of the target area, a second phase map corresponding to the target area in the first phase map (602), so as to pay attention to a phase map corresponding to the target object; acquiring, according to size information of the target object, an estimated distance of the target object from the ToF sensor (4033) (603); calculating, according to the estimated distance and the second phase map, an unwrapping coefficient corresponding to each pixel in the target area (604), the unwrapping coefficient indicating a real signal period at which each pixel is located; and determining a depth map of the target area according to the unwrapping coefficient and the second phase map (605), wherein the depth map is capable of visualizing the real distance corresponding to each pixel. The actual distance of the target object can be measured in the single frequency distance measurement technology, and the measurement precision can be ensured.

Description

Object ranging method and device

technical field

The present application relates to the technical field of three-dimensional distance measurement, and in particular to a method and device for object distance measurement.

Background technique

The time of flight (TOF) ranging method mainly uses the round-trip flight time of the optical signal sent by the transmitter between the target object and the receiver to calculate the distance from the target object to the TOF ranging system. The time of flight is more difficult. The TOF ranging system can calculate the distance by measuring the phase delay between the transmitted signal and the reflected signal, and use the depth map to represent the distance information corresponding to the surface of the target object.

The TOF ranging system can use single-frequency ranging technology. The single-frequency ranging technology means that the TOF ranging system uses a modulation frequency to transmit optical signals and performs ranging based on phase delay. Under this modulation frequency, the maximum distance that can be measured within one signal period is called the ambiguity distance. If the actual distance between the TOF ranging system and the target object exceeds the fuzzy distance, phase winding will occur. The phase winding phenomenon means that the measured value of the phase delay of the reflected signal may be different from the actual value. If the actual value exceeds one signal period, it will be subtracted by N 2π (N is a positive integer), so that the measured value falls on the signal Period, so there may be a difference of N×2π between the actual value and the measured value. For example, if the fuzzy distance is 0.5 meters, when measuring the distance of an object exceeding 0.5 meters, the TOF ranging system will calculate the distance as a distance between 0 meters and 0.5 meters due to the phenomenon of phase winding, which causes the measured distance to be different from that of Phenomena where the real distance is different. Therefore, in the single-frequency ranging technology, in order to make the measured value the same as the real value, it is necessary to expand the fuzzy distance as much as possible. The ambiguity distance is inversely correlated with the modulation frequency. In order to expand the measurable range, the modulation frequency can be reduced to increase the ambiguity distance. However, the modulation frequency is also related to the measurement accuracy, and reducing the modulation frequency will increase the measurement error.

In the single-frequency ranging technology, how to measure the real distance without increasing the measurement error has become an urgent problem to be solved.

Contents of the invention

The embodiment of the present application provides a TOF object ranging method. In the single-frequency ranging technology, even if the position of the measured object exceeds the fuzzy distance, the real distance to the target object can be measured, and the measurement accuracy can be guaranteed.

In the first aspect, an embodiment of the present application provides a method for measuring distance from an object, including: using a time-of-flight TOF sensor to acquire a first image and a first phase image corresponding to the first image; identifying a target area corresponding to a target object in the first image , and the second phase map corresponding to the target area in the first phase map; obtaining the estimated distance of the target object from the TOF sensor according to the size information of the target object, wherein the size information includes the image size of the target object in the first image, or, The actual physical size of the target object; calculating the unwrapping coefficient corresponding to each pixel in the target area according to the estimated distance and the second phase map; determining the depth map of the target area according to the unwrapping coefficient and the second phase map.

The first image can be a grayscale image or a color image; the target area can be understood as a region of interest (ROI) area, and the target area is used for the object ranging device to pay attention to the phase image corresponding to the target object; The size information of the object obtains the estimated distance of the target object from the TOF sensor, which can be understood as an approximate distance from the target object to the TOF sensor; the unwrapping coefficient is used to indicate the real signal period corresponding to each pixel in the target area; the depth map Used to visualize the true distance corresponding to each pixel in the target area. In the embodiment of the present application, it is not necessary to reduce the modulation frequency to extend the blur distance, but to determine an estimated distance between the target object and the TOF sensor through the size information of the object, and calculate the unwrapping corresponding to each pixel in the target area based on the estimated distance coefficient, the unwrapping coefficient can indicate the signal cycle corresponding to the target object, and the unwrapping coefficient corresponding to each pixel can be determined, and the real distance corresponding to each pixel can be determined, even if the actual distance of the target object exceeds the fuzzy distance, the target can also be detected The actual distance of the object, and can guarantee the measurement accuracy.

In an optional implementation, the size information of the target object is the image size of the target object, and the estimated distance between the target object and the TOF sensor is obtained according to the size information of the target object, including: according to the image size of the target object, and the preset relationship Determine the estimated distance, the preset relationship indicates that the multiple first distances have a corresponding relationship with multiple preset image sizes, the image size of the target object is the target preset image size among the multiple preset image sizes, and the estimated distance is the target preset image size. Assume that image sizes have a first distance of correspondence.

The image size is the number of pixels occupied by the target object in the first image, and the object ranging device locally stores the corresponding relationship between multiple first distances and multiple preset image sizes, and the multiple first distances and multiple preset The image size and corresponding relationship are obtained based on empirical values. The object ranging device determines the number of pixels corresponding to the target area, that is, determines the image size of the target object. If the image size of the target object is one of the multiple preset image sizes For the target preset image size, based on the above preset relationship, it is determined that the estimated distance is the first distance having a corresponding relationship with the target preset image size. In the traditional single-frequency ranging technology, when the position of the target object exceeds the fuzzy distance, only a few possible positions of the target object can be calculated, and the single-frequency ranging technology can calculate the possible signal periods corresponding to multiple measured objects ( Corresponding to the possible position), but it is impossible to determine which signal cycle the real position of the measured object corresponds to, which signal cycle the real position of the measured object corresponds to can be represented by the unwrapping coefficient. In the current technology, only in the multi-frequency ranging technology , the unwrapping coefficient can be calculated, that is to say, in the current single-frequency ranging technology, the unwrapping coefficient is not involved, but in this embodiment, the unwrapping technology can be calculated in the single-frequency ranging technology, and the object ranging device The approximate distance between the target object and the object distance measuring device can be judged according to the number (number) of pixels occupied by the target area in the first image, so that the distance corresponding to each pixel in the target area can be calculated according to the approximate distance and the second phase map. The unwrapping coefficient, and compared with the traditional method in which only the multi-frequency ranging technology can calculate the unwrapping coefficient, the solution in this embodiment can save the power consumption of the object distance measuring device.

In an optional implementation, the size information of the target object is the actual physical size of the target object, and the estimated distance between the target object and the TOF sensor is obtained according to the size information of the target object, including: calculating the distance between the target object and the TOF sensor according to the second phase map A plurality of second distances between the sensors, each of the plurality of second distances corresponds to an estimated size of a target object; matching the actual physical size of the target object with the plurality of estimated sizes, and determining the actual physical size The estimated size of the matched target; determining the second distance corresponding to the estimated size of the target as the estimated distance.

Due to the phase winding phenomenon, the object ranging device calculates multiple distances (also called "second distances") between the target object and the TOF sensor according to the second phase map, and the multiple second distances are the distance between the target object and the TOF Multiple possible distances, that is, the possible appearance positions of the target object, the object ranging device can calculate the estimated size of a target object according to each of the multiple second distances, that is, each second distance corresponds to a target The estimated size of the object; the object ranging device matches the actual physical size of the target object with a plurality of estimated sizes, and determines the estimated size of the target matching the actual physical size, wherein the actual physical size of the target object is an empirical value, for example, The category of the target object is a human face, and the actual width of the human face is about 15 cm; the object ranging device determines that the second distance corresponding to the estimated size of the target is the above estimated distance. In the traditional single-frequency ranging technology, when the position of the target object exceeds the fuzzy distance, only a few possible positions of the target object can be calculated, and the single-frequency ranging technology can calculate the possible signal periods corresponding to multiple measured objects ( Corresponding to the possible position), but it is not possible to determine which signal cycle the real position of the measured object corresponds to. Which signal cycle the real position of the measured object corresponds to can be represented by the unwrapping coefficient. In the current technology, only in the multi-frequency ranging technology In order to calculate the unwrapping coefficient, that is to say, the current single-frequency ranging technology does not involve the unwrapping coefficient, but in this embodiment, the unwrapping technology can be calculated in the single-frequency ranging technology. The distance device can select a second distance from a plurality of calculated distances (second distances) as an estimated distance according to the actual physical size of the target object, thereby being able to calculate the distance of each pixel in the target area according to the estimated distance and the second phase map. Corresponding unwrapping coefficients, and compared to the traditional method in which only the multi-frequency ranging technology can calculate the unwrapping coefficients, the solution in this embodiment can save the power consumption of the object distance measuring device.

In an optional implementation manner, before obtaining the estimated distance between the target object and the TOF sensor according to the size information of the target object, the method includes: determining the category of the target object; The category obtains the size information of the target object.

The object ranging device can determine the category of the target object through machine vision technology. For example, the category of the target object can be human face, hand, machine part, etc.; the size information of the target object can be obtained by querying the database according to the category. The database includes Dimensional information for various classes of objects. In this embodiment, the object ranging device can locally store size information of multiple types of objects, so that the above object ranging method can be applied to multiple types of objects, thus making the method suitable for various application scenarios.

In an optional implementation manner, the category of the target object is a human face.

In an optional implementation, the target area includes a first area and a second area; when there is no phase inversion in phase delays corresponding to multiple pixels in the target area, the unwrapping corresponding to each pixel in the target area The coefficients are the same; or, when the phase delays corresponding to multiple pixels in the target area have phase inversion, the unwrapping coefficients include the first unwrapping coefficient and the second unwrapping coefficient, where the phase inversion refers to the first phase delay and the second phase delay The two phase delays are not in the same signal cycle, the first phase delay is the phase delay corresponding to multiple pixels in the first area, and the second phase delay is the phase delay corresponding to multiple pixels in the second area; the first phase delay is the same as the first phase delay The unwrapping coefficient is related, and the second phase delay is related to the second unwrapping coefficient; the first unwrapping coefficient is used to calculate the depth map corresponding to the first region, and the second unwrapping coefficient is used to calculate the depth map corresponding to the second region.

The first area and the second area are spatially continuous; phase inversion means that the first phase delay and the second phase delay are not in the same signal period, for example, the first phase delay is 355 degrees, and the second phase delay is 365 degrees; according to The first phase delay is 355 degrees to calculate the first unwrapping coefficient N ₁ , and the second unwrapping coefficient N ₂ is obtained according to 5 degrees (the second phase delay is 365 degrees-360 degrees), for example, N ₁ =0, indicating that the first area corresponds to The first signal period, and N ₂ =1 indicates that the second area corresponds to the second signal period, N ₁ and N ₂ indicate the real positions corresponding to the first area and the second area, compared to the current single-frequency ranging technology Among them, the object ranging device cannot calculate the unwrapping coefficient. If the phase delay corresponding to the second area is 365 degrees, it will directly convert 365 degrees into 5 degrees (365 degrees-360 degrees), and calculate the distance according to the phase delay of 5 degrees. 5 degrees (measured value) and 365 degrees (true value) are different, which will cause incoherence in the depth value of the target area. In this embodiment, N ₁ and N ₂ indicate the corresponding depths of the first area and the second area. A signal period, where the signal period can indicate the actual distance corresponding to the first area and the second area, so that the depth of the target area is continuous and close to the above estimated distance.

In the second aspect, the embodiment of the present application provides an object distance measuring device, including: an acquisition module, configured to use a time-of-flight TOF sensor to acquire a first image and a first phase image corresponding to the first image; a processing module, configured to identify The target area corresponding to the target object in the first image, and the second phase image corresponding to the target area in the first phase image; the processing module is also used to obtain the estimated distance of the target object from the TOF sensor according to the size information of the target object, wherein , the size information includes the image size of the target object in the first image, or the actual physical size of the target object; the processing module is also used to calculate the unwrapping coefficient corresponding to each pixel in the target area according to the estimated distance and the second phase map; The processing module is further configured to determine the depth map of the target area according to the unwrapping coefficient and the second phase map.

In an optional implementation manner, the size information of the target object is the image size of the target object; the processing module is further configured to determine the estimated distance according to the image size of the target object and a preset relationship, and the preset relationship indicates a plurality of first The distance corresponds to a plurality of preset image sizes, the image size of the target object is the target preset image size in the plurality of preset image sizes, and the estimated distance is the first distance corresponding to the target preset image size.

In an optional implementation manner, the processing module is further specifically configured to: calculate a plurality of second distances between the target object and the TOF sensor according to the second phase map, and each second distance in the plurality of second distances corresponds to a The estimated size of the target object; matching the actual physical size of the target object with multiple estimated sizes to determine the estimated target size matching the actual physical size; determining the second distance corresponding to the estimated target size as the estimated distance.

In an optional implementation manner, the processing module is further specifically configured to: determine the category of the target object; and acquire size information of the target object according to the category.

In an optional implementation, the target area includes a first area and a second area; when there is no phase reversal in phase delays corresponding to multiple pixels in the target area, the unwrapping coefficients corresponding to each pixel in the target area are the same ;or,

When there is a phase inversion in the phase delays corresponding to multiple pixels in the target area, the unwrapping coefficient includes the first unwrapping coefficient and the second unwrapping coefficient, wherein the phase inversion means that the first phase delay and the second phase delay are not at the same One signal period, the first phase delay is the phase delay corresponding to multiple pixels in the first area, and the second phase delay is the phase delay corresponding to multiple pixels in the second area; the first phase delay is related to the first unwrapping coefficient, The second phase delay is related to the second unwrapping coefficient; the first unwrapping coefficient is used to calculate the depth map corresponding to the first region, and the second unwrapping coefficient is used to calculate the depth map corresponding to the second region.

In a third aspect, the embodiment of the present application provides an object ranging device, including a processor, the processor is coupled with at least one memory, and the processor is used to read the computer program stored in the at least one memory, so that The electronic device executes the method described in any one of the above first aspects.

In the fourth aspect, the embodiment of the present application provides a computer-readable storage medium for storing computer programs or instructions, and when the computer programs or instructions are executed, the computer or processor executes any one of the above-mentioned first aspects. the method described.

In the fifth aspect, the embodiment of the present application provides a computer program product including instructions, and when the instructions in the computer program product are executed by a computer or a processor, the computer or processor can realize any one of the above first aspects the method described.

Description of drawings

FIG. 1 is a schematic diagram of the TOF ranging principle;

FIG. 2 is a schematic diagram of a depth map;

Figure 3a is a schematic diagram of a scene where a measured object may appear in the single-frequency ranging technique;

Fig. 3b is a schematic diagram of the scene where the measured object may appear in the multi-frequency ranging technology;

FIG. 4 is a schematic structural diagram of a ranging system in an embodiment of the present application;

FIG. 5 is a schematic diagram of a transmitted signal and a reflected signal in an embodiment of the present application;

FIG. 6 is a schematic flow chart of the steps of an object ranging method in the embodiment of the present application;

7 is a schematic diagram of a target area in the first image and a second phase image corresponding to the target area in the embodiment of the present application;

Fig. 8 is a relationship diagram of the number of pixels occupied by faces at different distances in the embodiment of the present application;

FIG. 9 is a schematic diagram of a plurality of second distances and the actual physical size of a human face corresponding to each second distance in the embodiment of the present application;

FIG. 10 is a schematic structural diagram of an embodiment of an object ranging device in the embodiment of the present application;

FIG. 11 is a schematic structural diagram of an embodiment of an electronic device in the embodiment of the present application.

Detailed ways

In this application, unless otherwise specified, the parts that are the same or similar among the various embodiments can be referred to each other. In the various embodiments in this application, and the various implementation methods/implementation methods/implementation methods in each embodiment, if there is no special description and logical conflict, different embodiments, and each implementation method/implementation method in each embodiment The terms and/or descriptions between implementation methods/implementation methods are consistent and can be referred to each other. Different embodiments, and the technical features in each implementation manner/implementation method/implementation method in each embodiment are based on their inherent Logical relationships can be combined to form new embodiments, implementation modes, implementation methods, or implementation methods. The following embodiments of the present application are not intended to limit the protection scope of the present application.

It can be understood that some optional features in the embodiments of the present application, in some scenarios, can be independently implemented without relying on other features, such as the current solution on which they are based, to solve corresponding technical problems and achieve corresponding effects , and can also be combined with other features according to requirements in some scenarios. Correspondingly, the devices provided in the embodiments of the present application can also correspondingly implement these features or functions, which will not be repeated here.

In the description of the present application, unless otherwise stated, "plurality" means two or more than two. "At least one of the following" or similar expressions refer to any combination of these items, including any combination of single or plural items. For example, at least one item (piece) of a, b, or c can represent: a, b, c, a and b, a and c, b and c, or a and b and c, wherein a, b, c can be single or multiple.

In addition, in order to clearly describe the technical solutions of the embodiments of the present application, in the embodiments of the present application, words such as "first" and "second" are used to distinguish the same or similar items with basically the same function and effect. Those skilled in the art can understand that words such as "first" and "second" do not limit the number and execution order, and words such as "first" and "second" do not necessarily limit the difference. Meanwhile, in the embodiments of the present application, words such as "exemplary" or "for example" are used to represent examples, illustrations or descriptions. Any embodiment or design solution described as "exemplary" or "for example" in the embodiments of the present application shall not be interpreted as being more preferred or more advantageous than other embodiments or design solutions. Rather, the use of words such as "exemplary" or "such as" is intended to present relevant concepts in a concrete manner for easy understanding.

An exemplary description of the principle of TOF ranging: Please refer to Figure 1 for understanding. When measuring the distance of the measured object, the modulated light source emits a high-frequency infrared modulation signal to illuminate the target object, and then the modulated signal is reflected back to the sensor of the TOF ranging system surface, a distance-dependent phase delay occurs. The TOF sensor receives and demodulates the phase delay caused by the flight process, and then calculates the distance between the sensor and the target object based on known quantities such as light flight speed and modulation frequency. In order to obtain the complete three-dimensional information of the target object and reconstruct the surface shape of the target object through the two-dimensional TOF sensor array, each pixel unit in the TOF sensor array is required to independently receive and demodulate the distance from each corresponding point on the object surface information, and then obtain the depth map of the target object. A depth image, also called a range image, refers to an image in which the distance (depth) of each point on the measured object is collected as a pixel value. The depth map directly reflects the geometry of the visible surface of the measured object. Please refer to FIG. 2, the visualized depth map is shown in FIG. 2, different depth values are mapped to different colors, and thus the depth map is visualized in a color image.

TOF ranging includes single-frequency ranging technology and multi-frequency ranging technology. The range of the traditional single-frequency ranging technology is limited. Under the single-frequency modulation frequency, it can only measure the objects within the fuzzy distance (as shown in the following formula (1)) and measure the distance according to the following formula (2). If the measured object If the position exceeds the ambiguity distance, the phenomenon of phase winding will appear. Please refer to Figure 3a for understanding. The single-frequency ranging technology can calculate the possible positions of multiple measured objects, but it cannot determine which signal period the real position of the measured object corresponds to. Among them, which signal corresponds to the real position of the measured object The period can be represented by the unwrapping coefficient. In the current technology, either in the single-frequency ranging technology, the modulation frequency is reduced, thereby expanding the fuzzy distance, so that the real distance of the measured object can fall within the range of the fuzzy distance, so that the measured object can be accurately measured, but this This method will reduce the measurement accuracy. Or use multi-frequency ranging technology, that is, add one or more modulating frequency modulation waves to measure the distance of the measured object in sequence, as shown in Figure 3b, each modulating frequency will correspond to a fuzzy distance, the real distance is how much The value measured by the modulation waves of two modulation frequencies, the real position corresponds to the modulation frequency, that is, the greatest common divisor of multiple frequencies, is called the beat frequency (beat frequency). The beating frequency will generally be lower, allowing longer measurement distances to be extended. For example, modulation frequency a = 100MHz, the ambiguity distance U _100MHz corresponding to modulation frequency a = 1.5m, modulation frequency b = 80MHz, and the ambiguity distance U _80MHz corresponding to modulation frequency b = 1.875m, after dual frequency, the ambiguity distance of the entire system Was extended to 7.5m. Although the multi-frequency ranging technology can accurately measure the real distance of the measured object, the multi-frequency ranging technology will increase the power consumption of the ranging system, reduce the frame rate, and limit the application scenarios of the ranging system.

Among them, c is the speed of light, and F is the modulation frequency.

where c is the speed of light,

is the phase delay, and F is the modulation frequency.

In view of the above problems, the present application proposes an object ranging method, which is applied to an object ranging system, please refer to FIG. 4 , which is a schematic structural diagram of the object ranging system. The ranging system includes a TOF module 40 and a processing module 41, wherein the TOF module 40 includes a TOF chip 403, a laser 402 and a lens 404 (including a filter). The TOF chip 403 includes a ToF sensor 4033 , a controller 4031 and an analog-to-digital converter (analog-to-digital converter, ADC) 4032 . Wherein, the controller 4031 is used for generating a transmission signal of a certain modulation frequency. A measure of a signal waveform change, usually in degrees (angles). Please refer to Fig. 5, the emitted infrared continuous optical signal (i.e. the transmitted signal) is a modulated cosine signal s(t), and the transmitted signal (also called "light wave signal") can be obtained by the following formula (3) express.

s(t)=cos(ωt), formula (3).

Among them, t represents the time, ω represents the angular velocity, and ωt represents the angle.

The controller 4031 sends electrical signals to the laser driver 401 and the TOF sensor 4033 respectively. The laser driver 401 is used to drive the laser 402 according to the change of the electrical signal, and the laser 402 is used to emit the corresponding optical wave signal s(t). The light wave signal is reflected by the measured object, the lens 404 is used to receive the reflected signal and send the reflected signal to the TOF sensor, the TOF sensor 4033 is used to receive the reflected signal g(t), and the reflected signal g(t) contains phase delay The modulated cosine signal and the reflected signal g(t) can be expressed by the following formula (4).

Among them, A represents the amplitude, t represents the time, ω represents the angular velocity,

Indicates phase delay, phase delay

Represents the propagation delay of light waves during flight.

The TOF sensor 4033 is also used for mixing and integrating s(t) and g(t) (as shown in the following formula 5) to obtain the integral value, which is output to the processing module 41 through the ADC4032, and the processing module 41 is used to process the integral value Phase calculation and intensity calculation, so as to obtain the grayscale image and phase image of the measured object.

Among them, s(t) represents the transmitted signal, g(t) represents the reflected signal,

Indicates mutual correlation.

The controller 4031 can select 4 different τ values: τ ₀ = 0°, τ ₁ = 90°, τ ₂ = 180° and τ ₃ = 270°. The 4 different τ values are respectively substituted into the above formula (5), A four-phase integrated value (also called 4-phase bare data) is obtained. The ADC4032 outputs the four-phase integral value to the processing module 41 . The processing module 41 is used to perform phase calculation (as shown in the following formula (6)) and intensity calculation (as shown in the following formula (7) and formula (8)) according to the four-phase bare data. The phase delay in the following equation (6)

For obtaining the phase image of the object under test, the intensity B in the following formula (7) can be used to obtain the grayscale image of the object under test.

B=c(τ)+c(τ+180°), formula (8).

Wherein, in the above formula (8), τ may be 0° or 90°.

The processing module 41 is used to identify the target area corresponding to the target object in the grayscale image, and the phase image corresponding to the target area; the processing module 41 can obtain the estimated distance from the target object to the TOF sensor 4033 according to the size information of the target object, and according to the estimated distance and The phase map calculates the unwrapping coefficient corresponding to each pixel in the target area, determines the unwrapping coefficient, that is, determines the signal period corresponding to each pixel in the target area, and then can determine the target according to the unwrapping coefficient and the phase map corresponding to the target area Depth map of the region. In the embodiment of the present application, in the single-frequency ranging technology, it is not necessary to extend the ambiguity distance by reducing the modulation frequency as in the current technology, but to determine an estimated distance from the target object to the TOF sensor through the size information of the object, based on the estimation Distance calculates the unwrapping coefficient corresponding to each pixel in the target area. After determining the unwrapping coefficient corresponding to each pixel, the real distance corresponding to each pixel can be determined. Even if the actual distance of the target object exceeds the fuzzy distance, the target can also be detected The actual distance of the object, and can guarantee the measurement accuracy.

The technical solutions of the present application are illustrated below through specific examples. An object ranging method provided in an embodiment of the present application may be executed by an object ranging device. In one implementation, the structure of the object ranging device is as shown in FIG. 4 above. The object ranging device includes a TOF module and a processing module. In one example, the TOF module and the processing module are integrated in the same in the device. For example, the object distance measuring device is a dedicated distance measuring device, or the object distance measuring device may be a terminal. Terminals include but are not limited to mobile phones, computers, tablet computers, vehicle terminals, smart homes (such as smart TVs), game devices, robots, etc. In another implementation manner, the TOF module and the processing module can be respectively set in different devices. For example, the TOF module is set in the TOF camera, the processing module is set in the object distance measuring device, the TOF camera and the object distance measuring device are connected in communication, the object distance measuring device can be a terminal, or the object distance measuring device can also be a terminal In the processor, the terminals include but are not limited to mobile phones, computers, tablet computers, vehicle terminals, smart homes (such as smart motors), game devices, robots, etc. Please refer to FIG. 6 , the object ranging device performs the following steps 601 to 605 .

Step 601. The object ranging device acquires a first image and a first phase map corresponding to the first image by using a TOF sensor.

The object ranging device uses the TOF sensor to acquire the first image. In an optional situation, the first image is a grayscale image of the scene to be photographed. The first image is obtained by using the above formula (7) or the above formula (8). . Optionally, if the object ranging device further includes a color image sensor, the first image may also be an RGB (red, green, blue) image. For example, the object ranging device is a mobile phone, the mobile phone includes a color image sensor, and the first image is an RGB image collected by the mobile phone through the color image sensor.

The object ranging device uses the TOF sensor to obtain raw data (or called raw data), and calculates the gray value corresponding to each pixel in the first image and the phase delay corresponding to the light wave flight time according to the raw data, and then obtains the corresponding phase delay of the first image. The first phase diagram of . Based on the principle of TOF ranging, when measuring the distance of the target object, the modulated light source emits a high-frequency infrared modulation signal to irradiate the target object, and then when the modulated signal is reflected back to the surface of the TOF sensor, a distance-related phase delay occurs. Each pixel in the first image corresponds to a phase delay in the first phase map, and the first phase map can indicate the distance information between the target object and the object distance measuring device (refer to the above formula (2) for understanding).

Step 602, the object ranging device identifies a target area corresponding to the target object in the first image, and a second phase image corresponding to the target area in the first phase image.

Please refer to FIG. 7 , which is a schematic diagram of a target area of the first image and a second phase map corresponding to the target area. The object ranging device identifies a target area in the first image, where the target area is a position corresponding to the target object in the first image. The object ranging device confirms the target area in the first image, and determines the second phase map corresponding to the target area in the first phase map according to the position of the target area.

The method for identifying the target area by the object ranging device is not limited. Exemplarily, in a possible implementation, the object distance measuring device has a built-in object recognition model, such as the object recognition model can be a neural network model, and the object distance measuring device uses the object recognition model to identify the target object and mark the target object location information. In another possible implementation, the target area can also be the focus area of the TOF sensor. For example, the TOF sensor receives the light waves reflected by the target object to perform automatic focusing. For example, in the first image, the target object can pass through one side The area enclosed by the frame is the focus area. The target area can be understood as a region of interest (region of interest, ROI). The ROI area is an image area selected from an image, and this area is a key area for image analysis.

Step 603, the object ranging device obtains the estimated distance of the target object from the TOF sensor according to the size information of the target object, wherein the size information includes the image size of the target object in the first image, or the actual physical size of the target object.

In mode A, the size information of the target object is the image size of the target object.

In this embodiment of the present application, the category of the target object is not limited. Exemplarily, the category of the target object is illustrated by taking a human face as an example. Please refer to FIG. 8 , which is a schematic diagram of the relationship between the number of pixels occupied by faces at different distances (the first distance). Figure 8 shows the number of pixels occupied by human faces captured by adults and children at different distances (first distance) from a certain camera with all parameters determined. The first distance is the multiple distances shown on the horizontal axis in FIG. 8 , and the multiple preset image sizes are the multiple sizes shown on the vertical axis in FIG. 8 . The number of pixels occupied by the face is the image size of the face. As the first distance increases, the number of pixels occupied by the face decreases, and correspondingly, as the first distance decreases, the number of pixels occupied by the face increases. Thus, the approximate position of the face can be roughly judged by the number of pixels occupied by the face.

The object ranging device determines the estimated distance according to the image size of the target object and a preset relationship. The estimated distance can be understood as an approximate distance. The object ranging device stores size information in advance, and the size information includes a plurality of first distances and a plurality of preset image sizes, and a one-to-one correspondence between the plurality of first distances and the plurality of preset image sizes. The image size of the target object is a target preset image size among the multiple preset image sizes, and the estimated distance is a first distance corresponding to the target preset image size.

For example, please refer to the above-mentioned FIG. 8 for understanding, image size=horizontal H (horizontal) pixels×vertical V (vertical). The target object takes a child's face as an example. For example, the image size is 100 pixels, and the first distance corresponding to 100 pixels is 0.6m. That is, when the image size of the target object is 100 pixels, it can be obtained according to the preset relationship The estimated distance is 0.6m.

In this implementation manner, the object ranging device may determine an approximate distance (estimated distance) between the human face and the ranging device according to the number of pixels occupied by the human face in the first image.

In implementation B, the size information of the target object is the actual physical size of the target object. The category of the target object is illustrated by taking a human face as an example.

The object ranging device calculates a plurality of distances (also referred to as "second distances") between the target object and the TOF sensor according to the second phase map, and each second distance in the plurality of second distances corresponds to an estimate of a target object size.

The object distance measuring device performs calculations based on the second phase diagram. Since there may be a phase winding phenomenon, that is, it is impossible to determine which signal period the actual distance of the target object corresponds to, multiple different distances will be calculated for different signal periods. Exemplarily, the object ranging device restores and calculates three distances from the second phase image, and the positions corresponding to these three distances are positions where human faces may appear. Please refer to Fig. 9 for understanding, the positions where faces may appear are 25cm, 75cm and 125cm respectively. For example, the object ranging device calculates the corresponding three human face sizes according to the three distances, and the human face widths (estimated sizes) can be calculated to be 5cm, 15cm and 25cm respectively. That is, when the face position is 25cm, the estimated width of the corresponding face is 5cm; when the face position is 75cm, the estimated width of the corresponding face is 15cm; when the face position is 125cm, the estimated width of the corresponding face is 25cm.

A brief description of how to calculate the face width. Exemplarily, the field of view of the camera is known. For example, the field of view is m degrees. In the grayscale image, the width of the first image occupies p pixels, and the width of the face occupies q pixels. Therefore, FIG. 9 The middle α angle is calculated according to the following formula (9).

Further, according to

and the second distance, the estimated width (estimated size) of the human face can be calculated through a trigonometric calculation formula. It should be noted that the number of the second distances here is just an example for convenience of description, and the number of the second distances may be more in a process of actual application.

The object ranging device matches the actual physical size of the target object with a plurality of estimated sizes to determine the estimated size of the target that matches the actual physical size.

Exemplary, based on empirical values, the actual physical size of the human face is 15cm (the approximate width of the human face), and the actual physical size of the target object is matched with multiple estimated sizes (5cm, 15cm and 25cm), then the target estimated size It is 15cm.

The object ranging device determines that the second distance corresponding to the estimated size of the target is the estimated distance D _E .

The target estimated size (15cm) is the size closest to the real face width (that is, the actual physical size of the face), so 75cm corresponding to 15cm is selected as the estimated distance.

In this implementation, the object ranging device can restore the possible position of the target object according to the second phase map, and can calculate the estimated size of the target object based on multiple possible positions, and further, select An estimated size (target estimated size) that matches (closest to) the actual physical size of the target object, and the second distance corresponding to the estimated target size is used as the estimated distance.

Step 604, the object ranging device calculates the unwrapping coefficient corresponding to each pixel in the target area according to the estimated distance and the second phase map.

The unwrapping coefficient is used to indicate the signal period corresponding to the actual position of the target object. Please refer to FIG. 3a for understanding. The traditional single-frequency ranging technology can calculate the possible positions of multiple measured objects, but cannot determine which signal period the real position of the measured object corresponds to. In this embodiment, which signal cycle corresponds to the real position of the measured object can be represented by the unwrapping coefficient. Since the maximum distance that the object distance measuring device can measure within one signal period is an ambiguity distance, the unwrapping coefficient can also be understood as: used to indicate which ambiguity distance the actual position of the target object is within.

The object ranging device calculates the unwrapping coefficient according to the following formula (10):

Among them, N represents the unwrapping coefficient, round represents rounding calculation, D _E represents the estimated distance, U represents the fuzzy distance,

Indicates phase delay.

In a specific implementation, since the human face has depth, there may be a phase reversal in the phase delay corresponding to the pixels in the target area. Wherein, the target area corresponding to the face in the first image includes the first area and the second area, and the first area and the second area are spatially continuous without depth jump, that is to say, in the grayscale image (RGB image) The entire face area in is smooth.

Phase inversion means that the first phase delay and the second phase delay are not in the same signal cycle, the first phase delay is the phase delay corresponding to multiple pixels in the first area, and the second phase delay is the phase delay corresponding to multiple pixels in the second area phase delay. To illustrate the phase reversal phenomenon, for example, the first area is the area corresponding to the nose tip area of the human face, and the second area is the area corresponding to the ears of the human face. The position of the nose tip is closer to the object distance measuring device than the position of the ear. If A signal period is [0 degrees, 360 degrees], the phase delay corresponding to at least one pixel in the nose tip area is 355 degrees, and the phase delay corresponding to at least one pixel in the ear area is 365 degrees, that is, the phase delay corresponding to the nose tip area and the ear If the phase delay corresponding to the region is not within one signal period, it indicates that there is a phase inversion in the target region.

Whether there is phase inversion based on the phase delay corresponding to the pixels in the target area, including the following

cases

1 and 2.

Case 1: When the phase delays corresponding to multiple pixels in the target area do not have phase inversion, the unwrapping coefficients corresponding to each pixel in the target area are the same. In this case, the unwrapping coefficients corresponding to all the pixels in the target area are the same value, and the depth values of multiple pixels in the target area are close to the estimated distance D _E .

Case 2: When the phase delays corresponding to multiple pixels in the target area have phase inversion, the unwrapping coefficients include a first unwrapping coefficient and a second unwrapping coefficient. Wherein, the first phase delay is related to the first unwrapping coefficient, and the second phase delay is related to the second unwrapping coefficient. The first unwrapping coefficient is used to calculate the depth map corresponding to the first region, and the second unwrapping coefficient is used to calculate the depth map corresponding to the second region.

Exemplarily, the first phase delay of 355 degrees is substituted into the above (10) to obtain the first unwrapping coefficient N ₁ , and the phase delay of 5 degrees (the second phase delay of 365 degrees - 360 degrees) is substituted into the above formula (10) The second unwrapping coefficient N ₂ is obtained. For example, N ₁ =0 indicates that the tip of the nose corresponds to the first signal period, while N ₂ =1 indicates that the ear corresponds to the second signal period. N1 and N2 indicate the real positions corresponding to the first area and the second area.

Step 605, the object ranging device determines the depth map of the target area according to the unwrapping coefficient and the second phase map.

The object ranging device calculates the actual distance corresponding to each pixel in the target area according to the unwrapping coefficient and the second phase map. The object ranging device can calculate the actual distance corresponding to each pixel according to the following formula (11).

in,

is the phase delay, N is the unwrapping coefficient, and U is the ambiguity distance.

In case 1 above, the entire object area uses the same unwrapping coefficient to calculate the actual distance corresponding to each pixel. In the above case 2, the first area uses the first unwrapping coefficient to calculate the actual distance corresponding to each pixel in the first area, and the second area uses the second unwrapping coefficient to calculate the actual distance corresponding to each pixel in the second area , that is, different unwrapping coefficients are used in different regions within the target region. For example, N ₁ =0 indicates that the tip of the nose corresponds to the first signal period, and N ₂ =1 indicates that the ear corresponds to the second signal period, and N1 and N2 indicate the corresponding real positions of the first area and the second area. Compared with the current single-frequency ranging technology, the object ranging device will not calculate the unwrapping coefficient. If the phase delay corresponding to the ear is 365 degrees, it will directly convert 365 degrees into 5 degrees (365 degrees-360 degrees), according to The above formula (2) is used to calculate the distance, and the corresponding distances of 5 degrees and 365 degrees are different, thus, the depth value of the face area will be incoherent, and in this embodiment, _N1 and _N2 indicate the first The two signal periods corresponding to the area and the second area can indicate the real positions corresponding to the first area and the second area, so that a coherent depth map can be finally generated based on the target area corresponding to the face.

According to the above formula (11), the object ranging device can calculate the actual distance corresponding to each pixel in the target area. In order to reconstruct the three-dimensional information in the real scene, further data processing is required. The three-dimensional coordinates corresponding to each pixel are calculated according to the two-dimensional coordinates of each pixel and the real distance D _r corresponding to each pixel, please refer to the following formulas (12) to (14).

Z _w =D _r , formula (14).

Among them, (u _i , v _i ) represents the i-th pixel point, u ₀ , v ₀ represent the coordinates of the optical center in the image coordinate system, f _x represents the focal length in the horizontal direction, and f _y represents the focal length in the vertical direction . (X _w , Y _w , Z _w ) represent coordinates in the world coordinate system.

In the embodiment of the present application, the ranging device obtains the approximate distance (estimated distance) between the target object and the TOF sensor according to the size information of the target object, and can calculate the solution corresponding to each pixel in the target area according to the estimated distance and the phase map. The unwrapping coefficient and unwrapping coefficient can indicate the signal cycle of each pixel corresponding to the target object. According to the unwrapping coefficient and phase map of each pixel, the real distance corresponding to each pixel can be determined, that is, the depth map of the target area can be obtained. Compared with the traditional method, in the single-frequency ranging technology, the depth map of the target area corresponding to the target object can be obtained without reducing the modulation frequency to increase the blur distance, thereby ensuring the ranging accuracy.

In a specific embodiment, the above-mentioned target objects are illustrated by taking human faces as an example. In the embodiment of the present application, the category of the target object is not limited. In different application scenarios, the target object may belong to different categories. Before the above step 403, the above method may further include the following steps.

The object ranging device uses machine vision technology to identify the category to which the target object belongs, and queries the object size information corresponding to each category that has been stored in the database according to the category to which the target object belongs.

For example, the category of the target object is a human face, and the object ranging device queries the size information of the human face in the database. In the above method A, the size information includes the size information in step 603 in the above embodiment, the size information a includes multiple first distances a and multiple preset face image sizes, and multiple first distances a and Correspondence of multiple preset face image sizes. In the above method B, the size information of the human face is the actual physical size of the human face (eg, the width of the human face is 15 cm).

Application scenarios of face ranging. 1. The object ranging device is a vehicle-mounted terminal. The vehicle-mounted terminal can accurately detect the position of the driver's head to judge whether the driver is focused enough and whether he is driving fatigued, so as to initiate corresponding countermeasures. 2. The object ranging device is a mobile terminal (such as a mobile phone, a tablet computer, etc.). Compared with the traditional 2D face recognition technology, the mobile terminal recognizes 3D faces, and the bioactivity detection is accurate and safe, so that the embodiments of the present application The object ranging method in the paper is applied to face unlocking, mobile payment application scenarios, etc.

In another example, if the category of the target object is a hand, the object ranging device queries the size information of the hand in the database. In the above method A, the size information includes size information b, and the size information b includes a plurality of first distances b and a plurality of preset hand image sizes, and a plurality of first distances b and a plurality of preset hand image sizes corresponding relationship. In the above method B, the size information is the actual physical size of the hand.

Application scenarios of limb distance measurement. 1. The object ranging device is a vehicle-mounted terminal. The object ranging device detects various positions of the user's hand during the movement process to control the vehicle entertainment system or the vehicle air conditioner. 2. The object distance measuring device is a smart TV or a computer. The object distance measuring device detects the position of the user's hand and outputs a corresponding game interface to realize human-computer interaction.

For another example, the type of the target object is a machine part, and the object ranging device queries the size information of the machine part in the database. In the above method A, the size information includes size information c, and the size information c includes a plurality of first distances c and a plurality of preset machine part image sizes, and a plurality of first distances c and a plurality of preset machine part image sizes corresponding relationship. In the above method B, the size information is the actual physical size of the machine parts.

Application scenarios of distance measurement of machine parts. 1. The object distance measuring device is an industrial robot, and the object distance measuring device detects the position of the machine parts, so that the machine parts can be accurately positioned and placed.

It should be noted that the above categories of target objects and corresponding application scenarios are only for illustration, and do not constitute a limiting description of the present application.

Referring to FIG. 10 , an embodiment of the present application provides an object distance measuring device 1000 , which is used to execute the method performed by the object distance measuring device in the foregoing method embodiments. The object ranging device includes an acquisition module 1001 and a processing module 1002 .

An acquisition module 1001, configured to acquire a first image and a first phase map corresponding to the first image by using a time-of-flight TOF sensor;

A processing module 1002, configured to identify a target area corresponding to the target object in the first image, and a second phase image corresponding to the target area in the first phase image;

The processing module 1002 is further configured to acquire the estimated distance of the target object from the TOF sensor according to the size information of the target object, wherein the size information includes the image size of the target object in the first image, or the actual physical size of the target object;

The processing module 1002 is further configured to calculate an unwrapping coefficient corresponding to each pixel in the target area according to the estimated distance and the second phase map;

The processing module 1002 is further configured to determine a depth map of the target area according to the unwrapping coefficient and the second phase map.

Optionally, the function of the obtaining module 1001 may be performed by a transceiver. Wherein, the transceiver has the function of sending and/or receiving. Optionally, the transceiver is replaced by a receiver and/or transmitter.

Optionally, the function of the obtaining module 1001 may also be executed by a processor.

Optionally, the processing module 1002 is a processor, and the processor is a general-purpose processor or a special-purpose processor. Optionally, the processor includes a transceiver unit configured to implement receiving and sending functions. For example, the transceiver unit is a transceiver circuit, or an interface, or an interface circuit. The transceiver circuits, interfaces or interface circuits for realizing the functions of receiving and sending are deployed separately, and optionally integrated together. The above-mentioned transceiver circuit, interface or interface circuit is used for reading and writing codes or data, or the above-mentioned transceiver circuit, interface or interface circuit is used for signal transmission or transmission.

Further, the acquiring module 1001 is configured to execute step 601 in the above method embodiment, and the processing module 1002 is configured to execute step 602 to step 605 in the above method embodiment.

In a specific embodiment, the size information of the target object is the image size of the target object;

The processing module 1002 is further configured to determine the estimated distance according to the image size of the target object and a preset relationship, the preset relationship indicates that multiple first distances have a corresponding relationship with multiple preset image sizes, and the image size of the target object is multiple The estimated distance of the target preset image size in the preset image size is the first distance corresponding to the target preset image size.

In a specific implementation manner, the processing module 1002 is also specifically configured to:

calculating a plurality of second distances between the target object and the TOF sensor according to the second phase map, and each second distance in the plurality of second distances corresponds to an estimated size of the target object;

Matching the actual physical size of the target object with the plurality of estimated sizes to determine the estimated size of the target that matches the actual physical size;

The second distance corresponding to the estimated size of the target is determined as the estimated distance.

Determine the category of the target object;

Obtain the size information of the target object according to the category.

In a specific implementation manner, the category of the target object is a human face.

In a specific embodiment, the target area includes a first area and a second area;

When the phase delays corresponding to multiple pixels in the target area do not have phase inversion, the unwrapping coefficients corresponding to each pixel in the target area are the same; or, when the phase delays corresponding to multiple pixels in the target area have phase inversion, The unwrapping coefficient includes the first unwrapping coefficient and the second unwrapping coefficient, wherein, the phase inversion means that the first phase delay and the second phase delay are not in the same signal period, and the first phase delay is corresponding to multiple pixels in the first area The second phase delay is the phase delay corresponding to multiple pixels in the second area; the first phase delay is related to the first unwrapping coefficient, and the second phase delay is related to the second unwrapping coefficient; the first unwrapping coefficient It is used to calculate the depth map corresponding to the first region, and the second unwrapping coefficient is used to calculate the depth map corresponding to the second region.

Please refer to FIG. 11, the embodiment of the present application provides an object distance measuring device 1100, the object distance measuring device is used to execute the method performed by the object distance measuring device in the above method embodiment, please refer to the above method embodiment for details illustrate. Object ranging devices include but are not limited to mobile phones, computers, tablet computers, vehicle terminals, smart homes (such as smart TVs), game devices, robots, etc. In the embodiment of the present application, a mobile phone is taken as an example of an object distance measuring device for description. The object ranging device 1100 includes a processor 1101 , a memory 1102 , an input unit 1103 , a display unit 1104 , a TOF module 1105 , a communication unit 1106 , an audio circuit 1107 and other components. The memory 1102 can be used to store software programs and modules, and the processor 1101 executes various functional applications and data processing of the device by running the software programs and modules stored in the memory 1102 . The memory 1102 may include a high-speed random access memory, and may also include a non-volatile memory, such as at least one magnetic disk storage device, flash memory device, or other volatile solid-state storage devices. Optionally, the processor 1101 includes, but is not limited to, various types of processors, such as one or more of a CPU, a DSP, and an image signal processor.

In a specific embodiment, the processor 1101 is configured to execute the functions executed by the processing modules in FIG. 5 above.

The input unit 1103 can be used to receive inputted number or character information, and generate key signal input related to user settings and function control of the device. Specifically, the input unit 1103 may include a touch panel 1131 . The touch panel 1131, also referred to as a touch screen, can collect touch operations of the user on or near it (for example, the user uses any suitable object or accessory such as a finger or a stylus on the touch panel 1131 or near the touch panel 1131). operate).

The display unit 1104 can be used to display various image information. The display unit 1104 may include a display panel 1141. Optionally, the display panel 1141 may be configured in the form of a liquid crystal display, an organic light emitting diode, or the like. In some embodiments, the touch panel 1131 can be integrated with the display panel 1141 to realize the input and output functions of the device.

The TOF module 1105 is used to generate a transmission signal of a certain frequency, receive the reflection signal reflected by the object under test (target object), generate raw data according to the transmission signal and the reflection signal, and transmit the raw data to the processor 1101 . The processor 1101 is configured to generate a grayscale image and a phase image according to the raw data, and generate a depth image corresponding to the target object according to the grayscale image and the phase image. For the structure of the TOF module 1105 , please refer to the structure of the TOF module 40 in FIG. 5 above for understanding.

The communication unit 1106 is configured to establish a communication channel, so that the object distance measuring device is connected to a remote server through the communication channel, and obtain an object detection model and a scene recognition model from the remote server. The communication unit 1106 may include communication modules such as a wireless local area network module, a bluetooth module, a baseband module, and a radio frequency (radio frequency, RF) circuit corresponding to the communication module, for performing wireless local area network communication, Bluetooth communication, infrared communication and/or cellular communication. Communication system communication. The communication module is used to control the communication of each component in the object ranging device, and can support direct memory access.

Optionally, various communication modules in the communication unit 1106 generally appear in the form of integrated circuit chips, and can be selectively combined without including all communication modules and corresponding antenna groups. For example, the communication unit 1106 may only include a baseband chip, a radio frequency chip and corresponding antennas to provide communication functions in a cellular communication system. Via the wireless communication connection established by the communication unit 1106, the object ranging device can be connected to a cellular network or the Internet.

Audio circuitry 1107, speaker 1108, and microphone 1109 may provide an audio interface between the user and the handset. The audio circuit 1107 can transmit the electrical signal converted from the received audio data to the speaker 1108, and the speaker 1108 converts it into an audio signal for output. The microphone 1109 converts the collected sound signal into an electrical signal, which is converted into audio data after being received by the audio circuit 1107, and then the audio data is processed by the output processor 1101, and then sent to, for example, another mobile phone through the communication unit 1106, or the audio data Output to memory 1102 for further processing.

Although not shown, the object ranging device may also include more components, such as a camera, a power supply, etc., which will not be described in detail.

The embodiment of the present application also provides a computer-readable storage medium for storing computer programs or instructions. When the computer programs or instructions are executed, the computer executes the method of the object distance measuring device in the above method embodiments.

An embodiment of the present application provides a chip, and the chip includes a processor and a communication interface, where the communication interface is, for example, an input/output interface, a pin, or a circuit. The processor is used to read instructions to execute the method executed by the object ranging device in the above method embodiment.

The embodiment of the present application also provides a computer program product. The computer program product includes computer program code. When the computer program code is executed by a computer or a processor, the computer or processor implements the object distance measuring device in the above method embodiment. Methods.

A computer program product includes one or more computer instructions. When the computer program instructions are loaded or executed on the computer, the processes or functions according to the embodiments of the present application will be generated in whole or in part. The computer can be a general purpose computer, a special purpose computer, a computer network, or other programmable devices. Computer instructions may be stored in or transmitted from one computer-readable storage medium to another computer-readable storage medium, e.g. Coaxial cable, optical fiber, digital subscriber line (DSL)) or wireless (such as infrared, wireless, microwave, etc.) to another website site, computer, server or data center. The computer-readable storage medium may be any available medium that can be accessed by a computer, or a data storage device such as a server or a data center that includes one or more sets of available media. The available media may be magnetic media (eg, floppy disk, hard disk, magnetic tape), optical media (eg, DVD), or semiconductor media. The semiconductor medium may be a solid state drive (SSD).

As mentioned above, the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: it can still understand the foregoing The technical solutions recorded in each embodiment are modified, or some of the technical features are replaced equivalently; and these modifications or replacements do not make the essence of the corresponding technical solutions depart from the scope of the technical solutions of the embodiments of the present invention.

Claims

A method for measuring distance from an object, comprising:

acquiring a first image and a first phase map corresponding to the first image by using a time-of-flight TOF sensor;

identifying a target region corresponding to the target object in the first image, and a second phase map corresponding to the target region in the first phase map;

Acquiring an estimated distance between the target object and the TOF sensor according to the size information of the target object, wherein the size information includes the image size of the target object in the first image, or, the target object's actual physical size;

calculating an unwrapping coefficient corresponding to each pixel in the target area according to the estimated distance and the second phase map;

Determining a depth map of the target region according to unwrapping coefficients and the second phase map.
The method according to claim 1, wherein the size information of the target object is the image size of the target object, and the estimated distance between the target object and the TOF sensor is acquired according to the size information of the target object ,include:

The estimated distance is determined according to the image size of the target object and a preset relationship, the preset relationship indicates that a plurality of first distances have a corresponding relationship with a plurality of preset image sizes, and the image size of the target object is the a target preset image size among the plurality of preset image sizes, and the estimated distance is a first distance corresponding to the target preset image size.
The method according to claim 1, wherein the size information of the target object is the actual physical size of the target object, and the estimated distance between the target object and the TOF sensor is obtained according to the size information of the target object distance, including:

calculating a plurality of second distances between the target object and the TOF sensor according to the second phase map, each second distance in the plurality of second distances corresponds to an estimated size of the target object;

matching the actual physical size of the target object with a plurality of the estimated sizes, and determining an estimated target size matching the actual physical size;

A second distance corresponding to the estimated size of the target is determined as the estimated distance.
The method according to any one of claims 1-3, wherein before obtaining the estimated distance between the target object and the TOF sensor according to the size information of the target object, the method comprises:

determining the category of the target object;

The size information of the target object is acquired according to the category.
The method according to any one of claims 1-4, wherein the category of the target object is a human face.
The method according to any one of claims 1-5, wherein the target area comprises a first area and a second area;

When the phase delays corresponding to multiple pixels in the target area do not have phase inversion, the unwrapping coefficients corresponding to each pixel in the target area are the same;

or,

When the phase delays corresponding to multiple pixels in the target area have phase inversion, the unwrapping coefficients include a first unwrapping coefficient and a second unwrapping coefficient, wherein the phase inversion refers to the first phase delay and The second phase delay is not in the same signal period, the first phase delay is a phase delay corresponding to a plurality of pixels in the first region, and the second phase delay is a phase delay corresponding to a plurality of pixels in the second region;

The first phase delay is related to the first unwrapping coefficient, and the second phase delay is related to the second unwrapping coefficient; the first unwrapping coefficient is used to calculate the depth corresponding to the first region , the second unwrapping coefficient is used to calculate the depth map corresponding to the second region.
An object ranging device is characterized in that it comprises:

An acquisition module, configured to acquire a first image and a first phase map corresponding to the first image by using a time-of-flight TOF sensor;

A processing module, configured to identify a target area corresponding to the target object in the first image, and a second phase image corresponding to the target area in the first phase image;

The processing module is further configured to obtain an estimated distance between the target object and the TOF sensor according to the size information of the target object, wherein the size information includes the image size of the target object in the first image, or , the actual physical size of the target object;

A processing module, further configured to calculate an unwrapping coefficient corresponding to each pixel in the target area according to the estimated distance and the second phase map;

The processing module is further configured to determine the depth map of the target area according to the unwrapping coefficient and the second phase map.
The object ranging device according to claim 7, wherein the size information of the target object is the image size of the target object;

The processing module is further configured to determine the estimated distance according to the image size of the target object and a preset relationship, the preset relationship indicates that a plurality of first distances have a corresponding relationship with a plurality of preset image sizes, and the target The image size of the object is a target preset image size among the plurality of preset image sizes, and the estimated distance is a first distance corresponding to the target preset image size.
The object ranging device according to claim 7, wherein the processing module is further specifically used for:

calculating a plurality of second distances between the target object and the TOF sensor according to the second phase map, each second distance in the plurality of second distances corresponds to an estimated size of the target object;

matching the actual physical size of the target object with a plurality of the estimated sizes, and determining an estimated target size matching the actual physical size;

A second distance corresponding to the estimated size of the target is determined as the estimated distance.
The object ranging device according to any one of claims 7-9, wherein the processing module is further specifically used for:

determining the category of the target object;

The size information of the target object is acquired according to the category.
The object ranging device according to any one of claims 7-10, wherein the type of the target object is a human face.
The object ranging device according to any one of claims 7-11, wherein the target area includes a first area and a second area;

When the phase delays corresponding to multiple pixels in the target area do not have phase inversion, the unwrapping coefficients corresponding to each pixel in the target area are the same;

or,

When the phase delays corresponding to multiple pixels in the target area have phase inversion, the unwrapping coefficients include a first unwrapping coefficient and a second unwrapping coefficient, wherein the phase inversion refers to the first phase delay and The second phase delay is not in the same signal period, the first phase delay is a phase delay corresponding to a plurality of pixels in the first region, and the second phase delay is a phase delay corresponding to a plurality of pixels in the second region;

The first phase delay is related to the first unwrapping coefficient, and the second phase delay is related to the second unwrapping coefficient; the first unwrapping coefficient is used to calculate the depth corresponding to the first region , the second unwrapping coefficient is used to calculate the depth map corresponding to the second region.
An object distance measuring device, characterized in that it includes a processor, the processor is coupled with at least one memory, and the processor is used to read the computer program stored in the at least one memory, so that the object distance measuring device Carrying out the method according to any one of claims 1 to 6.
A computer-readable storage medium is characterized in that it is used to store computer programs or instructions, and when the computer programs or instructions are executed, the computer or processor executes the method according to any one of claims 1 to 6.
A computer program product comprising instructions, characterized in that, when the instructions in the computer program product are executed by a computer or a processor, the computer or the processor is made to implement any of the above claims 1 to 6. method described in the item.