Parameterization process, device, system and corresponding program

Description

1. Technical field

[0001] The disclosure relates to the field of mobile mapping. More specifically, the disclosure relates to the field of data capture and processing from mobile mapping systems. Even more specifically, the disclosure concerns the configuration of image captures from a mobile mapping system equipped with at least three image capture devices. 2. Previous technique

[0002] Mobile mapping systems have been under development for many years. Such systems allow for the acquisition of three-dimensional data for mapped environments. Various technologies can be implemented within a mobile mapping system to obtain this three-dimensional data. In particular, panoramic cameras can be used. Panoramic cameras are often configured according to the same principle: a predetermined number of individual image-capturing devices (cameras) are distributed across a hemisphere, for example, six; five of them are placed on the same horizontal plane in a circle, and the sixth is oriented upwards to complete the panorama.

[0003] While theoretically interesting, these panoramic cameras, which incorporate multiple individual shooting devices, suffer from several problems. First, it is necessary to validate the temporal synchronization of these devices to ensure that images are captured simultaneously. One solution is to arbitrarily set gain and exposure time values ​​for the cameras. However, this significantly impacts image quality, particularly in low-light or bright lighting conditions. Another solution involves using a dedicated processor to address this synchronized adaptation issue. For example, Insta360 (Insta360, 2022) incorporates a powerful GPU to process images from its onboard cameras.This computer controls the data streams and standardizes the parameters of the image capture devices via onboard image processing. The principle is similar to the "automatic" mode of digital cameras; it uses the current image capture to estimate the new parameters for the next image. However, this solution is energy-intensive and also adds weight to the equipment, which is carried, for example, by an operator on foot: the computer, as well as a power supply sized for it, must be integrated into the system. Furthermore, regardless of the algorithms chosen (FLIR, 2017) or (Bernacki, 2020), the general principle remains the same, and the latency in adapting the parameters is inherent to this principle, which consists of controlling the parameters based on the image capture.A rapid change in lighting conditions (passing through a tunnel, sudden change in weather conditions) results in an adaptation time, leading to unusable images while the camera converges to the correct parameters.

[0004] It is therefore necessary to provide a solution that allows both the precise determination of the shooting conditions of the mobile mapping device during its movement and the avoidance of the problems posed by prior art solutions.

[0005] US patent 2022 / 086988 A1 describes a lighting system comprising an angularly variable LED (AVLED) capable of individually adjusting the luminous flux and, optionally, the spectral content in a plurality of angular compartments, and at least one light sensor, including an imaging sensor, positioned to receive light from the environment. The device emits a luminous flux in different angular compartments, and the sensor provides information about the light emitted from these compartments and reflected by the environment in one or more spatial areas, this information potentially including spectral data.This document further provides measurement routines including angular scanning to measure or estimate luminous properties and, where appropriate, to generate a map of the luminous field, and then to adjust the flux emitted in one or more angular compartments so as to achieve a target property in the areas considered, for example luminance, luminance or irradiance, while being able to take into account colorimetric or spectral properties of surfaces and reflected light. 3. Summary of the invention

[0006] The technique devised by the inventors has been tested to address, at least in part, the problems posed by the prior art. Thus, the present disclosure relates to a method for configuring a system comprising a set of N imaging devices as defined in the attached claim 1.

[0007] According to another aspect, the invention also relates to a panoramic camera system comprising a set of N shooting devices as defined in the attached claim 7.

[0008] According to a preferred implementation, the various steps of the processes according to this disclosure are implemented by one or more software or computer programs as defined in the attached claim 8.

[0009] Consequently, the present technique also aims at programs, capable of being executed by a computer or by a data processor, these programs comprising instructions to control the execution of the steps of the processes as mentioned above.

[0010] A program can use any programming language, and be in the form of source code, object code, or code somewhere between source code and object code, such as in a partially compiled form, or in any other desirable form.

[0011] The present technique also aims at an information support readable by a data processor, and containing instructions of a program as mentioned above.

[0012] The information medium can be any entity or terminal capable of storing the program. For example, the medium can include a storage means, such as a ROM, for example a CD ROM or a microelectronic circuit ROM, or a magnetic recording means, for example a mobile medium (memory card) or a hard drive or an SSD.

[0013] On the other hand, the information medium can be a transmissible medium such as an electrical, optical, and / or audio signal, which can be transmitted via an electrical or optical cable, by radio, or by other means. The program according to this technique can, in particular, be downloaded from a network such as the Internet.

[0014] Alternatively, the information carrier may be an integrated circuit in which the program is incorporated, the circuit being adapted to execute or to be used in the execution of the process in question.

[0015] In an example implementation, this technique is implemented using software and / or hardware components. In this context, the term "module" may refer in this document to a software component, a hardware component, or a set of hardware and software components.

[0016] A software component corresponds to one or more computer programs, one or more subroutines of a program, or more generally to any element of a program or software capable of implementing a function or set of functions, as described below for the module in question. Such a software component is executed by a data processor of a physical entity (terminal, server, gateway, set-top box, router, etc.) and is capable of accessing the hardware resources of that physical entity (memory, storage media, communication buses, input / output electronic cards, user interfaces, etc.).

[0017] Similarly, a hardware component corresponds to any element of a hardware assembly capable of implementing a function or set of functions, as described below for the module in question. This could be a programmable hardware component or one with an integrated processor for software execution, for example, an integrated circuit, a smart card, a memory card, an electronic board for running firmware, etc.

[0018] Each component of the system described above naturally implements its own software modules.

[0019] The different embodiments mentioned above can be combined with each other for the implementation of this technique. 4. Brief description of the drawings

[0020] Other aims, characteristics, and advantages of the described technique will become clearer upon reading the following description, given as a simple illustrative and non-limiting example, in relation to the figures, among which: there figure 1 represents the system schematically; the figure 2 represents the system in which flash devices are added; the figure 3 represents the system for synchronizing with an ambient light frequency; the figure 4 represents the parameterization process; the figure 5 represents a simplified physical architecture of a device in which the processes and systems previously described can be implemented. 5. Detailed description 5.1. General principle

[0021] As explained previously, the general principle implemented by the inventors consists of coupling a wide-field-of-view camera (i.e., a system comprising a plurality of individual camera sensors placed on the same horizontal plane) with a plurality of ambient light sensors, which are also placed on the same horizontal plane. The light sensors and the individual camera sensors are controlled by a microcontroller. This microcontroller receives, in real time, the measurements from the light sensors. This microcontroller also controls, in real time, the triggering of the individual camera sensors based on the measurements taken from the various light sensors. According to the present design, the system is equipped with at least three light sensors.In the case where the camera system is panoramic (360° field of view, with individual shooting devices placed on the same horizontal plane in a circle), at least three light sensors are combined to cover a panoramic field of view (with an approximate field of view of 120° for each light sensor located behind a standard lens, also placed on the same horizontal plane in a circle).

[0022] Light sensors are used to obtain an absolute measurement of environmental characteristics in terms of brightness, color temperature, and flicker (e.g., artificial neon lighting). In one embodiment, each light sensor can provide measurements on six simultaneous ambient light channels, allowing the calculation of illuminance, chromaticity, and color temperature (a broadband channel ( Wideband ) , a channel Clear,a channel Leakage ", three channels (R / G / B)).

[0023] There figure 1 This diagram illustrates the system developed by the inventors. A plurality of individual shooting devices (four are shown: C1, C2, C3, C4) are used to perform panoramic shooting within a panoramic shooting system. These individual shooting devices are physically aligned in the same horizontal plane, and their number depends on the viewing angle of each device (in the example shown in the diagram). figure 1The viewing angle would be at least 90° per individual camera, with each camera oriented at 90° to the other. The individual cameras are controlled by a microcontroller (µC) which is responsible for setting the shooting parameters and triggering the shots at a predetermined frequency. The optical flow from these individual cameras is not processed by the microcontroller itself, but by a separate device that is not the subject of this invention. The system is also equipped with light sensors (three are shown: A1, A2, and A3). Each sensor covers approximately a 120° field of view, thus covering the same field as the individual cameras.

[0024] Generally, if the system is not panoramic, it includes as many sensors as necessary to achieve the same field of view coverage as the individual camera units. For example, it is possible to build a 180° camera system comprising three individual camera units and two or three light sensors. Also generally, there are as many light sensors as there are camera units, or at least one fewer light sensor than there are camera units.

[0025] The absolute measurement of luminance (Cd / m², W / m² / sr, photons / s / m² / sr) provided by a light sensor installed on the system is linear with the amount of ambient light. The inventors used this characteristic to implement a suitable image capture parameterization method, overcoming several drawbacks of the prior art. Thus, the microcontroller, by retrieving the measurements from the light sensors, performs calculations based on the measured values ​​to obtain a single (but cleverly determined) exposure time for the individual image capture devices of the system, maximizing image quality and minimizing the exposure time of the sensors of these individual image capture devices.Thus, for example, if the ideal exposure time (calculated by the microcontroller) exceeds a maximum allowed value (e.g., a limit to prevent motion blur, configured within the microcontroller), the method includes a step to adjust the gains of the individual camera devices. A subsequent step involves measuring the color temperature, which also allows for the deduction of an absolute value to modify the white balance parameters of each individual camera device, to fine-tune the parameters of each individual camera. In one example embodiment, the various sensor measurements are used to determine a measurement average. This example embodiment is geared towards timed and synchronized shooting of all the individual camera devices in the system. The frame rate used could, for example, be 25 frames per second.Other production rates may be considered depending on the operational implementation conditions.

[0026] Also depending on operational conditions, and in an example of a complementary implementation shown in figure 2 The system includes high-power LED flash units (four are shown: F1, F2, F3, F4). In this example, there are as many high-power LED flash units as there are individual camera units in the system. These flash units are therefore arranged on the same horizontal plane, for example in a circle, to provide fill light during each individual camera unit's exposure. Each flash unit is connected to the microcontroller and receives a trigger signal from it at the same rate as the camera's exposures.

[0027] Thus, the proposed system significantly reduces latency in adapting parameters in highly dynamic lighting environments (tunnel entrances or exits, indoor / outdoor transitions, artificial lighting, etc.), and does so in real time. The parameters are applied immediately to the images being captured. In other words, parameter updates are calculated for the image being acquired and do not require, as in other systems, that parameters be calculated for the next image based on the current image.

[0028] Furthermore, unlike systems that incorporate powerful graphics processing units (GPUs) or custom-configured FPGAs, the computational load for implementing the described method is limited, even when the resolution of individual imaging devices is increased. Thus, even with solutions incorporating very high-resolution sensors, the solution offered by the system of the invention does not present any problems in managing large amounts of data. Moreover, there is no significant development required each time the reference of an individual imaging device is changed.Whereas in the context of an FPGA module, changing individual shooting devices involves a total redesign, requiring new developments on the FPGA to adapt to the new resolutions, the solution offered by the invention is resource-efficient and does not require a redesign of the system, but only, as explained later, an initial parameterization of the new individual shooting devices to be used.

[0029] Furthermore, as previously mentioned, white balance is handled absolutely for each individual camera. While prior art algorithms adjust the gain ratios between color bands to produce images that are generally "white" on average (which may not reflect reality given the ambient lighting temperature), the invention processes this parameter to correspond to the actual lighting conditions from the perspective of each individual camera, independently of the others.

[0030] For example, when shooting indoors, some light sources, such as fluorescent lights, can flicker due to the 50Hz mains power supply. The light emission then shifts to 100Hz, on each peak (positive or negative) of the alternating current. In the case of very high-resolution cameras, motion blur can quickly appear with relatively short exposure times. A camera can indeed expose for 2ms and can therefore capture successive images with a completely different light source depending on the shooting frequency (producing a stroboscopic effect). In other words, the flicker is offset from the actual shooting time: the first shot may be taken during the interval where there is no flicker, thus causing the system to miscalculate the next shot (exposure time too long), which can lead to overexposure.

[0031] Given this additional problem, the inventors used the proposed system to measure the ambient flicker produced by the lighting. The principle is explained in figure 3 This frequency (FL), once measured, is used to control all the microcontroller's trigger clocks and synchronize the exposure periods (pe) of the individual shooting devices (C1, ...) with the ambient lighting periods, taking into account the ambient light frequency (FL), thus minimizing the need to illuminate the scene. If scene lighting is still required, the high-power flash devices are triggered by the shooting, as explained previously. Therefore, the solution provides: An absolute measurement of ambient light, ensuring consistent image flow across all individual shooting devices by influencing exposure times, electronic gains, and white balance settings; simultaneous synchronization of all individual shooting devices on common parameters; instantaneous responsiveness to external lighting conditions by eliminating thresholds and filters in camera "automatic" exposure functions; an adjustable and hardware-independent configuration (scalable solution in terms of the number of cameras and camera resolution); a lightweight, low-cost architecture with minimal computing resources; and high-frequency measurement capability uncorrelated with camera exposure times, thus enabling automatic triggering and expansion of additional light sources.

[0032] Thus, in relation to the figure 4 The invention also relates to a method for setting up a system comprising a set of N camera sensors physically aligned and distributed in the same horizontal plane so as to cover a predetermined overall camera angle. Such a method comprises: a measurement step (10), from a set of N-1 light sensors (A1, A2, ...) physically aligned and distributed in the same horizontal plane so as to cover the predetermined overall shooting angle, each sensor in the sensor set being individually connected to the microcontroller (µC), at least one representative luminance data point (W1, W2, ...) perceived by each light sensor; a determination step (20), by the microcontroller (µC),based on representative data of the brightness (W1, W2, ...) perceived by each luminance sensor, and an exposure time (TE) of the N imaging devices; a parameterization step (30) of all the N imaging devices, by the microcontroller (µC), to which each shooting device of the set of N shooting devices is connected, using the exposure time (TE).

[0033] Thus, it is possible, thanks to this technique, to obtain, at little cost, a system which on the one hand is not energy-intensive, does not require expensive additional equipment and which produces shots of equal quality, regardless of lighting conditions. 5.2. Description of an example implementation

[0034] This section describes the implementation of parameter settings for individual image capture devices (such as cameras) to determine an exposure time and white balance for each individual shot. It is assumed that each individual shot is taken at a specific frame rate (e.g., 25 frames per second for video stream production, 5 frames per second for mapping a given area). Other image acquisition frequencies can also be determined as needed. Therefore, to achieve the required frame rate, each image capture device must be provided with minimum acquisition parameters based on that frame rate.

[0035] In the implementation example presented here, a light sensor operates at 50 Hz with an exposure time of 2 ms. To standardize image capture from the various imaging devices, the inventors decided to apply the same parameters to each device. However, certain initial calibration parameters make each imaging device unique. The inventors determined that, in the case of a synchronized set of imaging devices operating at a specific frame rate (fm), the light sensors, which are synchronized to the same clock, can optionally operate at a frequency several times higher (e.g., 5 to 10 times higher) to smooth the measurements over a sliding window of several consecutive values.

[0036] For each light sensor in the system, the following measurements are used, for example: A broadband intensity measurement mes W (wavelength from 400nm to 950nm), expressed proportionally in lux; Three measurements mes R, mes G and mes B to determine the colour temperature, expressed proportionally in lux.

[0037] Since these measurements are performed at a clock frequency ten times higher than that of image acquisition, an average value is calculated, per sensor: Mi < W, Mi < R, Mi < G and Mi < B, where "i" represents the index of the imaging device. (1<=i<=N).

[0038] Based on these average measurements obtained for each sensor, the exposure time of the imaging devices is determined. More specifically, the exposure time is determined and the analog gain of the (CMOS sensors of the) imaging devices is adjusted.

[0039] According to the invention, the analog gain is minimized to eliminate electronic noise from CMOS sensors. The algorithm therefore consists of favoring the setting of the exposure time ( t before adjusting the gain (g). In the case of a mobile application (i.e., a moving system), it is possible to define an exposure limit value to limit motion blur. This threshold is called Tmax. This Tmax threshold can also depend on the exposure limit value required to maintain the acquisition frequency, depending on the implementation conditions.

[0040] Determining the exposure time ( t ) understand : a step of calculating a compiled value MW of the broadband intensity averages M i< W; a step of calculating the exposure time te according to the following formula: t e = t ∝ 1 M W si t < T max T max sinon An analog gain adjustment step, according to the following formula, can then be performed: g ∝ 0 si t < T max log 2 T max M w sinon

[0041] Following the acquisition of these values, primarily the exposure time (te), the next step is to configure all the parameters of the N The image capture devices are controlled by the microcontroller. (µC), to which each The camera is connected. If the gain value also needs to be set, the gain setting (g) is also performed in this parameterization step. Depending on the implementation examples, the step of calculating the compiled MW value of the broadband intensity averages Mi < W may itself consist of an average calculation. In which case: M W = Mean M W i

[0042] Under other operating conditions, the maximum or minimum value or any other suitable calculation may be carried out with the aim of obtaining a common compiled intensity value in MW on the basis of which the calculation of the exposure time is carried out.

[0043] After or following the exposure time calculation, a common white balance setting is also performed. Adjusting the color response of a digital camera involves setting two ratios in its parameters. These two ratios may differ depending on the manufacturer's choice. For the purposes of this discussion, we assume that the camera uses the following ratios: r G / R = G R et r G / B = G B

[0044] This means that it is possible to adjust the white balance of the camera by changing the multiplication factor of the green pixels (G) relative to the red pixels (R) and blue pixels (B). It is understood that the response of one camera under specific conditions will not be identical to the response of a second camera under those same conditions. Calibration is therefore performed beforehand to allow a second camera to provide the same response as another second camera. Calibration is performed by determining two parameters. k And b , for each ratio and for each shooting device. The system's microcontroller therefore stores, in memory, for each shooting device, the parameters k And b necessary for calculating the two ratios r G / R And r G / B of each camera, according to the formula: r x , y = k x , y M x M y + b x , y

[0045] Using the light sensors, an average value Mi < R, Mi < G, and Mi < B is calculated for each sensor, where "i" represents the index of the imaging device. (1<=i<=N). The second step in calculating the white balance consists of calculating a compiled value MX of the means M i< X, and this for each component (R, G, B).

[0046] Depending on the implementation examples, the step of calculating the compiled value MX of the components R, G, B (M i < X) may itself consist of an average calculation. In which case: M X = Mean M X i

[0047] Under other operating conditions, the maximum or minimum value or any other suitable calculation may be performed with the aim of obtaining a common compiled MX value on the basis of which the calculation of ratios is performed. The third step in calculating white balance involves calculating the two ratios r G / R And r G / B of each camera, according to the formula presented previously: r G / R = k G / R M R M G + b G / R And r G / B = k G / B M B M G + b G / B

[0048] Following the acquisition of these ratios, the microcontroller performs the parameterization step for all N imaging devices. (µC). Unlike exposure time (te), however, each shooting device receives two ratio values ​​specific to it, which depend on the calibration performed on the shooting device during the construction of the system, for example.

[0049] Thus, according to the invention, thanks to the coupling performed between a microcontroller (µC), imaging devices (C1, ...) connected to this microcontroller (µC)and light sensors (A1, ...), it is possible to have an efficient and inexpensive system for synchronized, time-lapse photography in which each image from each shooting device benefits from identical quality to the others. The logic implemented on the microcontroller (µC), It is simple to implement, resource-efficient, and therefore requires no additional power supply. Ultimately, the system is inexpensive and flexible since it is possible to change the shooting devices without altering the microcontroller logic. Only initial parameters (such as the two parameters) need to be changed. k And b ) are updated in the system.

[0050] Regardless of the specific implementation, the settings for the image capture devices can be implemented either as a single block (i.e., all parameters are provided after they have all been calculated) or sequentially (each parameter—exposure time, gain, white balance—is provided as the calculations are performed). Once all parameters are provided, and depending on the shooting frequency (particularly the number of frames per second to be acquired, as well as the ambient light frequency, for example), the microcontroller triggers the synchronous shooting of the image capture devices. When no flash device is used, the measurements from the sensors can continue to be obtained by the microcontroller in parallel with the image capture, for example, to increase or maintain the originally set shooting frequency. 5.3. Other features and advantages

[0051] We present, in relation to the figure 5, a simplified architecture of a mobile mapping device (TProf) capable of performing all or part of the processing as previously described. A mobile mapping device includes a first electronic module comprising a memory 51, a processing unit 52 equipped, for example, with a microprocessor, and controlled by a computer program 53. The mobile mapping device optionally includes, for security features (for example, to prevent theft of hardware or compromise of stored data), such as the generation of cryptographic hardware, a second electronic module comprising a secure memory 54, which can be merged with the memory 51 (as indicated by the dotted line; in this case, the memory 51 is a secure memory), a secure processing unit 55 equipped, for example, with a secure microprocessor, and physical protection measures (physical protection around the chip, by lattice, vias, etc.).and protection on the data transmission interfaces, possibly merged with the processing unit 52), and controlled by a computer program 56 specifically dedicated to this secure processing unit 55, this computer program 56 implementing all or part of the processing method as previously described. The group consisting of the secure processing unit 55, the secure memory 54, and the dedicated computer program 56 constitutes the secure module (PS) of the mobile mapping device. In at least one embodiment, the present technique is implemented in the form of a set of programs installed partly or entirely on this secure portion of the mobile mapping device.In at least one other embodiment, the present technique is implemented as a dedicated component (CpX) capable of processing data from the processing units and installed partially or entirely on the secure portion of the mobile mapping device. Furthermore, the device also includes communication means (CIE), for example in the form of network components (Wi-Fi, 3G / 4G / 5G, wired, RFID / NFC, Bluetooth, BLE, LPWAN, VLC, etc.) that enable the device to receive data (I) from entities connected to one or more communication networks and to transmit processed data (T) to such entities.

[0052] Such a device further comprises a system according to the invention including: an assembly comprising shooting devices physically aligned and distributed in the same horizontal plane so as to cover a predetermined overall shooting angle; an assembly of light sensors physically aligned and distributed in the same horizontal plane so as to cover the predetermined overall shooting angle, each sensor in the sensor assembly being individually connected to a microcontroller; means for calculating, in the form of a program implemented on the microcontroller, the shooting parameters of the shooting devices, based on the values ​​obtained from the light sensors; means for synchronizing the triggering of the shots based on the implemented shooting parameters.

[0053] These means can be supplemented by additional lighting means, illuminating the scene covered by the overall shooting angles and triggerable, according to the values ​​measured by the sensors, according to a predetermined frequency.

Claims

1. A method for parameterizing a system including a set of N imaging devices (C1, C2, ...) that are physically aligned and distributed in the same horizontal plane so as to cover a predetermined total imaging angle, wherein the method includes: - a step of measuring (10), based on a set of N-1 brightness sensors (A1, A2, ...) that are physically aligned and distributed in the same horizontal plane so as to cover the predetermined total imaging angle, wherein each sensor in the set of sensors is individually connected to a microcontroller (µC), at least one datum representative of the luminance (W1, W2, ...) detected by each brightness sensor; characterized in that the method further includes - a step of determining (20), by the microcontroller (µC), based on the data representative of the luminance (W1, W2, ...) detected by each brightness sensor, an exposure time (TE) of the N imaging devices; - a step of parameterizing (30) the set of N imaging devices (C1, C2, ...) using the exposure time (TE), wherein the parameterization is carried out by the microcontroller (µC), to which each imaging device of the set of N imaging devices is connected, wherein the method includes, for each imaging device, a step of determining the white balance as a function of a predetermined number of triplets of colour temperature values mesR, mesG and mesB, consisting in: for each sensor, calculating a triplet of average values MiR, MiG and MiB, for this sensor "i", wherein MiR corresponds to the average value of the colour temperature values mesR of said triplet, MiG corresponds to the average value of the colour temperature values mesG of said triplet, and MiB corresponds to the average value of the colour temperature values mesB of said triplet, - calculating a compiled value MX of the averages MiX, for each component (R, G, B), as a function of the triplets of average values; - calculating two ratios rG / R and rG / B for each imaging device "j", according to the formulae: r j G / R = k j G / R M R M G + b j G / R and r j G / B = k j G / B M B M G + b j G / B wherein the coefficients kjG / R and kjG / B and the biases bjG / R and bjG / B are predetermined during the calibration of each imaging device.

2. A parameterization method according to claim 1, wherein the step of measuring (10) includes, for each brightness sensor of the system: - a step of obtaining a predetermined number of broadband intensity values mesW, in the wavelength range from 400 nm to 950 nm, representative of the luminance expressed proportionally in lux; - a step of obtaining the predetermined number of triplets of colour temperature values, mesR, mesG and mesB, expressed proportionally in lux; - at least one step of transmitting these values (mesW, mesR, mesG and mesB) to the microcontroller (µC).

3. A method according to claim 1, wherein the step of determining an exposure time (20) includes: - a step of calculating a compiled value MW of the data representative of the luminance (W1, W2); - a step of calculating the exposure time te according to the following formula: t e = t ∝ 1 M W si t < T max T max wherein Tmax is representative of a predetermined maximum exposure time.

4. A method according to claim 3, wherein the step of calculating the compiled value MW of the data representative of the luminance (W1, W2) consists in a calculation of an average value of the data representative of the luminance (W1, W2).

5. A method according to claim 3, wherein, following the step of determining the exposure time, the method includes a step of adjusting an analogue gain g of each imaging device, according to the following formula: g ∝ 0 si t < T max log 2 T max M w 6. A method according to claim 1, wherein the measurement step further includes a step of determining a frequency (FL) of the ambient light.

7. A panoramic camera system including a set of N imaging devices that are physically aligned and distributed in the same horizontal plane so as to cover a predetermined total imaging angle, which system further includes: - a microcontroller (µC); - a set of N-1 brightness sensors that are physically aligned and distributed in the same horizontal plane so as to cover the predetermined total imaging angle, wherein each sensor in the set of sensors is individually connected to the microcontroller (µC); characterized in that each imaging device of the set of N imaging devices is individually connected to the microcontroller (µC) to receive, from this microcontroller (µC), imaging parameters determined as a function of luminance data captured from the set of N-1 brightness sensors and processed by the microcontroller (µC), wherein the system is configured to implement the method according to claim 1.

8. A computer program product including program code instructions for implementing a parameterization method according to claim 1, when the method is executed by the device according to claim 7.