FR3074950A1 - DATA PROCESSING METHOD AND ASSOCIATED INBOARD SYSTEM - Google Patents

Abstract

A method of data processing comprises the following steps: acquisition (E2) of a first set (Mk) of pixels by a sensor facing an environment; determination (E4) of a position (POS) of an object (O) of the environment; determination (E6, E8) of a second set (Sk) of pixels included in the first set (Mk) of pixels, the second set (Sk) of pixels covering said position (POS) and being distinct from the first set (Mk) ); - applying (E10) a processing algorithm to the pixels of the second set (Sk) only. An associated embedded system is also described.

Description

Data processing method and associated embedded system

Technical field to which the invention relates

The present invention relates generally to the field of processing the data acquired by a sensor.

It relates more particularly to a data processing method and an associated embedded system.

TECHNOLOGICAL BACKGROUND

Particularly known are the data processing methods in which a sensor (in general a matrix sensor) acquires a set of pixels, which are then processed in order to obtain information relating to the environment facing the sensor.

Such solutions are used in particular in the field of vehicles, whether for example to construct a map of the environment located at the front of the vehicle or to recognize gestures made by the driver of the vehicle.

The processing algorithms used are however more and more complex and thus consumers of material resources (microprocessor, memory, etc.).

Object of the invention

In this context, the invention proposes a data processing method comprising the following steps:

- acquisition of a first set of pixels by a sensor facing an environment;

- determination of a position of an object of the environment;

- determination of a second set of pixels included in the first set of pixels, the second set of pixels covering said position and being distinct from the first set;

- application of a processing algorithm to the pixels of the second set only.

The processing algorithm is thus applied to only a subset of the acquired pixels, which limits the volume of data handled. Thanks to the location of the object, the treatments carried out focus on the area of the environment in which the application of the processing algorithm is of interest.

Other non-limiting and advantageous characteristics of the data processing process, taken individually or in any technically possible combination, are the following:

- the sensor is matrix;

- the first set of pixels is a matrix of pixels;

the step of determining the second set of pixels comprises a step of determining an area comprising said position and / or a step of extracting the pixels of the first set located in said area;

- the sensor delivers a plurality of first sets of pixels;

the method comprises a step of determining, for each of said first sets of pixels, a second set of corresponding pixels by extraction of the pixels of the first set concerned located in said area (the same area thus being used for the different first sets) ;

- the sensor is part of a time-of-flight sensor further comprising an electromagnetic radiation emitting element;

- said first sets are acquired by the sensor respectively in correspondence with distinct phases of the signal (modulated) emitted by the element emitting electromagnetic radiation;

- Said position is determined by analysis of an image representative of the environment (such as at least part of the first set of pixels or an image obtained using the aforementioned processing algorithm);

said position is determined by monitoring the object (typically by evaluating a speed of the object in the image between two successive images and estimating the new position of the object on the basis of this speed and a position of the object in the previous image).

The invention also provides an on-board system comprising a processing unit and a sensor facing an environment, in which the sensor is designed to acquire a first set of pixels and in which the processing unit comprises a module designed to determine a position of an environment object, a module designed to determine a second set of pixels included in the first set of pixels (the second set of pixels covering said position and being distinct from the first set), and a module designed to apply a pixel processing algorithm of the second set only.

The optional characteristics mentioned above in terms of process can possibly apply to such an on-board system.

Detailed description of an exemplary embodiment

The description which follows with reference to the appended drawings, given by way of nonlimiting examples, will make it clear what the invention consists of and how it can be carried out.

In the accompanying drawings:

- Figure 1 shows an on-board system comprising a time-of-flight sensor;

- Figure 2 shows the functional modules of a processing unit of the embedded system of Figure 1; and

- Figure 3 shows pixel matrices processed by a processing method using the invention.

There is schematically shown in FIG. 1 a system on board a vehicle, here a motor vehicle, and comprising a time-of-flight sensor 1 and a processing unit 10.

The time of flight sensor 1, here a three-dimensional camera based on the time of flight principle (in English ToF 3D camera for Time of Flight 3D camera), comprises at least one element emitting electromagnetic radiation 2 (typically one or more diode (s) emitting (s) emitting in the infrared) and a matrix sensor 4 (such as an image sensor sensitive to the radiation emitted by the emitting element 2, here the infrared) defining a set of pixels.

The radiation E emitted by the emitting element 2 (generally through an optical emission system not shown in Figure 1) is reflected towards the matrix sensor 4 (radiation referenced R in Figure 1) by the first object encountered on the path of radiation E.

In practice, an optical system (such as a lens) is placed opposite the matrix sensor 4 so that each pixel of the matrix sensor 4 receives the reflected signal R coming from a particular direction of the solid angle analyzed by the time of flight sensor 1.

As shown in FIG. 1, a processing unit 10 (for example an electronic control unit or, in general, a microcontroller) controls the emission of E radiation by the emitting element 2, then analyzes the signals measured by the sensor matrix 4 (represented here in the form of a plurality of matrices M _k of pixels) so as to determine in particular a matrix D comprising the distances d i of the first object encountered for a plurality of directions of space facing the time sensor flight 1.

This matrix D of the distances dij (as well as possibly other information, such as a luminance matrix L) is transmitted by the processing unit 10 to another electronic system (not shown) for use by the latter.

For example, in the automotive field, the time of flight sensor 1 can be placed at the front of the vehicle in order to construct a map of the environment before the vehicle and / or to detect an obstacle and / or to assess the speed of another vehicle located at the front (by derivation of a distance from the vehicle evaluated on the basis of some of the distances dij).

According to another conceivable possibility, the time-of-flight sensor can be placed in the passenger compartment of the vehicle (for example facing the driver of the vehicle) and the distances dij determined by the processing unit 10 can be used within a gesture recognition algorithm.

In the example described here, the radiation E emitted by the emitting element 2 (under the control of the processing unit 10) is a modulated signal and the processing unit 10 controls the acquisition by the matrix sensor 4 d a plurality of matrices M _k of pixels, at times corresponding respectively to a plurality of distinct phases (two by two) of the modulated signal.

FIG. 2 represents the functional modules of the processing unit 10 useful for understanding the invention.

Each functional module 12, 14, 16 shown in FIG. 2 corresponds to a particular functionality implemented by the processing unit 10. Several (or even all) functional modules can however in practice be implemented by the same physical entity , here a processor of the processing unit 10, on which program instructions stored in a memory associated with the processor are executed (each functional module then being implemented in this case by the execution of a particular game d 'instructions stored in this memory).

The processing unit 10 thus comprises a localization module 12, a selection module 14 and an analysis module 16.

The location module 12 is designed to locate (roughly) an object present in the solid angle observed by the matrix sensor 4.

According to a first possible possibility, the location of the object is carried out by analysis of an image representative of the environment facing the matrix sensor 4 in the field of vision of the matrix sensor 4.

This representative image can in practice be one of the matrices M _k of pixels produced by the matrix sensor 4 or the luminance matrix L produced as indicated below by the analysis module 16, possibly (in both cases) after a step subsampling to reduce the volume of data processed.

This first possibility can be used in particular if no object has been detected beforehand.

According to a second possible possibility, the location of the object is carried out by monitoring the object and estimating the current position of the object (typically based on the position of the object at the previous iteration and an estimated displacement of the object from one iteration to the next iteration).

When the localization module 12 locates an object, the localization module 12 transmits position information POS to the selection module 14.

The position information POS includes, for example, coordinates of the detected object expressed relative to the pixel matrix acquired by the matrix sensor 4. These coordinates make it possible to define the position and / or the extent of the object concerned in the solid angle observed by the matrix sensor 4.

The selection module 14 also receives as input the pixel matrices Mk acquired by the matrix sensor 4.

As long as no object has been detected, the selection module 14 does not receive any position information POS and then transmits the pixel matrices M _k received as input to the analysis module 16 (without modification).

On the other hand, if an object is detected by the location module 12, the location module 12 transmits the position information POS to the selection module 14 as already indicated. The selection module 12 is then designed to:

- determine a zone Z covering the position (s) defined by the position information POS,

extracting, in each matrix M _k of pixels received at input, the pixels corresponding to the zone Z, which makes it possible to obtain for each matrix M _k of pixels a set S _k of pixels, and

transmitting the sets S _k of pixels to the analysis module 16.

The selection module 14 determines the zone Z in a predefined manner on the basis of the position information POS. For example, area Z includes all pixels located 10 pixels or less (vertically or horizontally) from the position defined by POS position information (including the defined pixel or pixels defined by POS position information) .

Each set S _k of pixels is therefore a subset of the set of pixels of a corresponding matrix M _k of pixels.

Note that, in the example described here, the same zone Z is used to extract the pixels from the different matrices M _k of pixels.

The analysis module 16 is designed to apply at least one processing algorithm to the sets S _k of pixels received at the input.

In the example described here, the analysis module 16 implements a first processing algorithm making it possible to obtain the matrix D of the distances dj, j on the basis of the sets S _k of pixels received at input (when the module of selection 14 performs the abovementioned extraction, or on the basis of the matrixes _{k k} of pixels when no object is detected by the localization module 12 and the selection module 14 then simply transmits these matrices M _k of pixels).

The analysis module 16 here also implements a second processing algorithm, making it possible to obtain the aforementioned luminance matrix L on the basis of the sets S _k of pixels received at input (or, as previously, on the base of the matrixes M _k of pixels).

We can refer for example to the technical document Time-of-Flight Camera- An Introduction, Texas Instruments, ref. SLOA190B, for more information on the treatments just described.

Thus, when an object is detected by the localization module 12, the processing algorithms are applied to only part of the pixels (the sets S _k ), which makes it possible to reduce the volume of the treatments carried out.

When the selection module 14 extracts pixels from the matrices M _k of pixels as indicated above and transmits to the analysis module 16 sets of pixels S _k , the matrix D of the distances djj and / or the luminance matrix L are generally partial (/.e .: do not include data for the entire field of vision of the matrix sensor 4).

We now describe with reference to FIG. 3 an example of a processing method implemented by the processing unit 10.

The matrix sensor 4 acquires at step E2 at least one matrix of pixels, here a plurality of matrix M _k of pixels as explained above.

The location unit 12 detects an object O in the environment facing the matrix sensor 4 (step E4) and determines its position POS, for example by analysis of one of the matrices M _k of pixels. As a variant, the detection of the object O could be carried out by analysis of a luminance matrix L calculated by the processing unit 10.

The selection module 14 then determines in step E6 an area Z covering the object O (and for example more extensive than the object O in order to take account of a margin of error).

For each matrix M _k of pixels, the selection module 14 extracts the pixels located in the zone Z in order to obtain a set S _k of corresponding pixels (step E8).

The analysis module 16 can thus apply at step E10 at least one processing algorithm to the sets S _k of pixels (and to these pixels only), here in order to obtain a (partial) matrix D of distances dij or a (partial) matrix of luminance L.

Claims (10)

1. Data processing method comprising the following steps: - acquisition (E2) of a first set (Mk) of pixels by a sensor (4) facing an environment; - determination (E4) of a position (POS) of an object (O) from the environment; determination (E6, E8) of a second set (Sk) of pixels included in the first set (M _k ) of pixels, the second set (Sk) of pixels covering said position (POS) and being distinct from the first set ( M _k ); - application (E10) of a processing algorithm to the pixels of the second set (Sk) only. 2. The processing method as claimed in claim 1, in which the sensor (4) is a matrix and in which the first set of pixels is a matrix of pixels (Mk). 3. Method according to claim 1 or 2, wherein the step of determining the second set of pixels comprises a step of determining (E6) an area (Z) comprising said position (POS) and a step of extracting ( E8) pixels of the first set (Mk) located in said zone (Z). 4. Method according to one of claims 1 to 3, wherein the sensor (4) delivers a plurality of first sets (Mk) of pixels. 5. Method according to claim 4 taken in dependence on claim 3, comprising a step of determining, for each of said first sets (Mk) of pixels, of a second set (Sk) of corresponding pixels by extraction of the pixels from the first set (Mk) concerned located in said zone (Z). 6. Method according to one of claims 1 to 5, wherein the sensor (4) is part of a time-of-flight sensor (1) comprising an element emitting electromagnetic radiation (2). 7. The method of claim 6 taken in dependence on claim 4 or 5, wherein said first sets (Mk) are acquired by the sensor (4) respectively in correspondence with distinct phases of the signal emitted by the transmitter element of electromagnetic radiation (2). 8. Method according to one of claims 1 to 7, wherein said position (POS) is determined by analysis of an image representative of the environment. 9. Method according to one of claims 1 to 7, wherein said position (POS) is determined by tracking the object (O). 10. On-board system comprising a processing unit (10) and a sensor (4) facing an environment, in which the sensor (4) is designed to acquire a first set (Mk) of pixels and in which the processing unit treatment (10) includes: - a module (12) designed to determine a position (POS) of an object (O) from the environment; - a module (14) designed to determine a second set (Sk) of pixels included in the first set (Mk) of pixels, the second set (Sk) of pixels covering said position (POS) and being distinct from the first set (M _k ); and - a module (16) designed to apply a processing algorithm to the pixels of the second set (Sk) only. 1/1