Management system for an adaptive lighting installation and corresponding method

Abstract

The invention relates to a system for managing a lighting installation (2) arranged to illuminate a traffic lane (1). An image acquisition device (3) makes it possible to generate a luminance image (Lmes) of an area (11) of the traffic lane. A processing unit (100) comprises several photometries (201, 202) of the lighting installation (2). The processing unit comprises a module (4) for determining a set of optical reflection characteristics of the traffic lane, and a control module (6) configured to control at least some of the lighting sources of the lighting installation (2), as a function of determined optical reflection characteristics, of at least some of the photometries of the lighting installation (2); and of reference luminance characteristics. The invention also relates to a corresponding method. Figure for abstract: Fig.1

Description

Title of the invention: System for managing an adaptive lighting installation and corresponding method FIELD OF THE INVENTION

[0001] The present invention relates generally to the management of a lighting installation, in particular for traffic lane lighting luminaires. PRIOR ART

[0002] It is desirable that traffic lanes be properly lit so that users of these lanes, such as pedestrians, cyclists or motorists, can move around safely, while limiting light pollution or energy waste.

[0003] The aim of the present invention is to propose a new lighting installation management system and a corresponding method making it possible to overcome all or part of the problems set out above. Summary of the invention

[0004] To this end, the invention relates to a system for managing a lighting installation arranged to illuminate a traffic lane, the lighting installation comprising a plurality of lighting sources whose electrical power supply is controllable, the management system comprising: - an image acquisition device for generating a luminance image, called a luminance map, of an area of the traffic lane; and - a data processing unit, the system being characterized in that said processing unit comprises: - several photometries of the lighting installation, each photometry being defined by a lighting source or a set of lighting sources forming part of said plurality of lighting sources of the lighting installation, and light intensity values that the lighting source or the set of lighting sources is capable of emitting in different directions; - a module for determining a set of optical reflection characteristics configured to determine a set of optical reflection characteristics of the traffic lane, as a function of the acquired luminance image; of at least part of the photometries of the lighting installation, and positioning data, such as height, of the illumination source(s) of said photometries relative to the area of the traffic lane; and a control module configured to control at least part of the lighting sources of the lighting installation, depending on the reflection characteristics determined optical characteristics, of at least part of the photometries of the lighting installation; and of reference luminance characteristics.

[0005] The system makes it possible to measure a change in optical properties of the traffic lane and to control the lighting installation to correct the lighting and thus obtain lighting adapted to reference criteria taking into account the optical properties of the traffic lane. These reference criteria may correspond to normative requirements.

[0006] The management system thus makes it possible to control the photometric operating characteristics (incident brightness) of the lighting luminaire(s) as a function of the optical properties of the material of the traffic lane. The optical properties may depend on the surface condition (dry, damp, wet, soaked, as well as new or worn) of the traffic lane.

[0007] The control module makes it possible, using the optical properties of the traffic lane determined from the information provided by the image acquisition device, to control the luminaires of the lighting installation according to a lighting scenario adapted to the optical reflection properties of the traffic lane to obtain desired luminance characteristics (reference criteria). The reference criteria preferably comprise a minimum average luminance value, a minimum general uniformity value and a minimum longitudinal uniformity value.

[0008] The system according to the invention thus makes it possible to optimize the operation of the lighting installation according to the optical reflection properties of the road to be illuminated.

[0009] Precise knowledge of the optical reflection properties of the traffic lane makes it possible to control the lighting installation to emit the necessary and sufficient quantity of light, and to distribute it over the desired surface of the traffic lane as uniformly as possible. In other words, the system according to the invention makes it possible to reliably determine optical reflection parameters, preferably at least 580 values of the actual r-table of the traffic lane, in order to be able to precisely adjust the distribution of the light intensity (illumination) to obtain a suitable average luminance and to optimize the general and longitudinal luminance uniformities.

[0010] According to one embodiment, the system also makes it possible to control the operation of the lighting installation taking into account the type of user, cyclist, pedestrian, motorist, etc., who is using the traffic lane.

[0011] The system may also include one or more of the following features taken in any technically admissible combination.

[0012] According to one embodiment, the control module is configured to: - define a plurality of lighting scenarios, each scenario including the pa following definition parameters: a photometry or a combination of photometries chosen from the photometries of the lighting installation, and one or more data relating to the power supply of the lighting source(s) of the photometry or combination of photometries chosen; - determine for each scenario, from the determined optical reflection characteristics of the traffic lane, the luminance characteristics of the traffic lane when said traffic lane is illuminated according to the definition parameters of said scenario, and - compare for each scenario the determined luminance characteristics of the traffic lane with the reference luminance characteristics; - identify the scenario for which the determined luminance characteristics are closest to the reference luminance characteristics; - control the lighting sources of the lighting installation which correspond to the identified scenario, according to the electrical power supply data used in the identified scenario.

[0013] According to one embodiment, the module for determining a set of optical reflection characteristics is configured to determine a set of optical reflection characteristics of the traffic lane by executing at least the following steps: - principal component analysis of sets of reference optical reflection characteristics to generate sets of virtual optical reflection characteristics, also called eigenvectors rvb rv2,..., rvD; - generation of several virtual luminance maps Lvb Lv2,..., LvD, based on: the eigenvectors rgb rv2,..., rvD, the positioning data of the lighting sources of the lighting installation, relative to the area of the traffic lane, and the photometry data during use of the lighting installation; - decomposition of the luminance map provided by the image acquisition device, on the virtual luminance maps Lvb Lv2,..., LvD, so as to obtain coefficients XbX2 XD associated with the virtual luminance maps; and - determination of the set of optical reflection characteristics of the traffic lane by linear combination of the eigenvectors rvb rv2,..., rvD with the coefficients XbX2 XD obtained.

[0014] According to one embodiment, the sets of optical reflection characteristics are r-tables, each r-table comprising values of a reduced luminance coefficient, noted r, defined according to the equation: with k a constant, and q a luminance coefficient defined by: "F with E the horizontal illumination generated by a lighting source, and L the luminance, q being a function of: - the observation angle a, - the angle [3 between the plane of incidence of the light from the lighting source and the observation plane, and - the angle of incidence y of the light, the r-table including values of r for different values of angle [3 and different values of tan y

[0015] According to one embodiment, the sets of reference optical reflection characteristics being reference r-tables, said reference r-tables comprise r-tables which have torque values {Q0; SI] different from each other, with: where Q is the solid angle containing all directions of incident light.

[0016] According to one embodiment, the sets of reference optical reflection characteristics comprising: - reference tables of class RI, R2, R3, R4, Cl, C2, NI, N2, N2, N4, Wl, W2, W3, and / or W4, and / or - experimentally measured r-tables.

[0017] According to one embodiment, the sets of virtual optical reflection characteristics are virtual r-tables, and, for the generation of several virtual luminance maps Lvi, Lv2,..., LvD, also called clean maps, the determination module is configured to apply, for each virtual r-table, and for each point P of the zone of the traffic lane of which the image is acquired, the equation: I — * V - to the lighting configuration of the lighting installation in operation, where Ns is the number of lighting sources considered for the calculation, yi>p is the angle of incidence of the ith lighting source at point P, k is a constant, Lp is the luminance at point P, ri>p are the reduced luminance coefficients of a virtual table, Eip are the elementary illuminations due to each lighting source separately at point P, calculated from the equation: where h is the height of the lighting source, I is the intensity emitted by the i-th lighting source of the lighting installation in the direction of point P.

[0018] According to one embodiment, the or each lighting source comprises one or more LEDs.

[0019] According to one embodiment, the lighting installation comprises several luminaires, each luminaire comprising a portion of said lighting sources of the lighting installation, each luminaire comprising a device for controlling the power supply of the lighting sources of the luminaire.

[0020] According to one embodiment, the reference luminance characteristics comprise at least one of the following characteristics: - the minimum average luminance of the traffic lane; - the general uniformity in minimum luminance of the traffic lane; and - the longitudinal uniformity in minimum luminance of the traffic lane.

[0021] According to one embodiment, the module for determining a set of optical reflection characteristics is configured to determine several r-tables of the traffic lane as a function of several types of user capable of traveling on said traffic lane with which different observation angles of the traffic lane are associated, the control module being configured for, for a given type of user traveling on the traffic lane: - select the determined table-r whose associated observation angle corresponds to the determined user type, and - control at least part of the lighting sources of the lighting installation, using the selected determined table-r.

[0022] The invention also relates to a method for managing at least one lighting installation arranged to illuminate a traffic lane, the lighting installation having several photometries, each photometry being defined by: - a lighting source or a set of lighting sources of the lighting installation, and - light intensity values that the lighting source or said set of lighting sources is capable of emitting in different directions; the method comprising acquiring an image of an area of the traffic lane to generate a luminance image of this area; characterized in that the method comprises the following steps: - determination of a set of optical reflection characteristics of the traffic lane area based on: - of the acquired luminance image; - at least part of the photometries of the lighting installation; positioning data, such as height, of the illumination source(s) of said photometries relative to the area of the traffic lane; and - control of at least part of the lighting sources of the lighting installation, as a function of: determined optical reflection characteristics, at least part of the photometries of the lighting installation; reference luminance characteristics.

[0023] According to one embodiment, the step of controlling the lighting sources is also carried out as a function of a type of user who is traveling on the traffic lane. Brief description of the drawings

[0024] Other characteristics and advantages of the invention will emerge from the following description, which is purely illustrative and non-limiting and must be read in conjunction with the appended drawings, in which:

[0025] - [Fig.l] [Fig.l] is a schematic view of a facility management system lighting configured to illuminate a traffic lane according to one embodiment of the invention;

[0026] - [Fig.2] [Fig.2] is a schematic representation illustrating several steps for the generation of a table-r of a traffic lane, such as that shown in [Fig.l], which can be implemented by the lighting installation system;

[0027] - [Fig.3] [Fig.3] is a schematic representation of useful angles for an ins installation of traffic lane lighting;

[0028] - [Fig.4] [Fig.4] is a percentage graph of the median of the qua error relative mean dramatic RRMSE for an embodiment of the invention;

[0029] - [Fig.5A] [Fig.5A] is a table corresponding to the RI table-r established by the CIE, used in one embodiment of the invention as a reference r-table for calculating virtual r-tables;

[0030] - [Fig.5B] [Fig.5B] is a table corresponding to table-r R2 established by the CIE, used in one embodiment of the invention as a reference r-table for calculating virtual r-tables;

[0031] - [Fig.5C] [Fig.5C] is a table corresponding to table-r R3 established by the CIE, used in one embodiment of the invention as a reference table-r for the calculation of virtual r-tables;

[0032] - [Fig.5D] [Fig.5D] is a table corresponding to table-r R4 established by the CIE, used in one embodiment of the invention as a reference r-table for calculating virtual r-tables;

[0033] - [Fig.5E] [Fig.5E] is a table corresponding to table-r Cl established by the CIE, used in one embodiment of the invention as a reference r-table for calculating virtual r-tables;

[0034] - [Fig.5F] [Fig.5F] is a table corresponding to table-r C2 established by the CIE, used in one embodiment of the invention as a reference r-table for calculating virtual r-tables;

[0035] - [Fig.5G] [Fig.5G] is a table corresponding to the NI table-r established by the CIE, used in one embodiment of the invention as a reference r-table for calculating virtual r-tables;

[0036] - [Fig.5H] [Fig.5H] is a table corresponding to table-r N2 established by the CIE, used in one embodiment of the invention as a reference r-table for calculating virtual r-tables;

[0037] - [Fig.51] [Fig.51] is a table corresponding to table-r N3 established by the CIE, used in one embodiment of the invention as a reference r-table for calculating virtual r-tables;

[0038] - [Fig.5J] [Fig.5J] is a table corresponding to table-r N4 established by the CIE, used in one embodiment of the invention as a reference r-table for calculating virtual r-tables;

[0039] - [Fig.5K] [Fig.5K] is a table corresponding to table-r W1 established by the CIE, used in one embodiment of the invention as a reference r-table for calculating virtual r-tables;

[0040] - [Fig.5L] [Fig.5L] is a table corresponding to table-r W2 established by the CIE, used in one embodiment of the invention as a reference r-table for calculating virtual r-tables;

[0041] - [Fig.5M] [Fig.5M] is a table corresponding to the table-r W3 established by the CIE, used in one embodiment of the invention as a reference r-table for calculating virtual r-tables;

[0042] - [Fig.5N] [Fig.5N] is a table corresponding to table-r W4 established by the CIE, used in one embodiment of the invention as a reference r-table for calculating virtual r-tables;

[0043] - [Fig.6A] [Fig.6A] is an example of a virtual r-table, denoted rgb obtained using reference r-tables and experimentally measured r-tables;

[0044] - [Fig.6B] [Fig.6B] is an example of a virtual r-table, denoted rv2, obtained using reference r-tables and experimentally measured r-tables;

[0045] - [Fig.7A] [Fig.7A] is an example of a virtual luminance map, denoted Lvl, obtained from virtual r-tables and photometry data of the lighting installation in operation;

[0046] - [Fig.7B] [Fig.7B] is an example of a virtual luminance map, denoted Lv2, obtained from virtual r-tables and photometry data of the lighting installation in operation;

[0047] - [Fig.8] [Fig.8] is an example of an estimated r-table for the traffic lane illuminated by the lighting installation, using a luminance image acquired from an area of said track and virtual luminance maps. DETAILED DESCRIPTION

[0048] The inventive concept is described more fully below with reference to the accompanying drawings, in which embodiments of the inventive concept are shown. In the drawings, the size and relative sizes of elements may be exaggerated for clarity. Like numerals refer to like elements throughout the drawings. However, this inventive concept may be embodied in many different forms and should not be construed as being limited to the embodiments set forth herein. Instead, these embodiments are provided so that this description is complete, and communicates the scope of the inventive concept to those skilled in the art.

[0049] A reference throughout the specification to "an embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment is included in at least one embodiment of the present invention. Thus, the occurrence of the phrase "in an embodiment" at various locations throughout the specification does not necessarily refer to the same embodiment. Furthermore, the particular features, structures, or characteristics may be combined in any suitable manner in one or more embodiments.

[0050] With reference to Figures 1 and 2, a system for managing a lighting installation is shown. The lighting installation is arranged to illuminate the traffic lane 1. As detailed below, the lighting installation management system is adaptive because the lighting (number of powered lighting sources, the power supply of the lighting sources, the spatial distribution of the light intensity of the installation) can be adapted according to the characteristics of the object and / or the environment of the object to be illuminated.

[0051] Optical reflection properties

[0052] The traffic lane has different optical reflection properties. According to one embodiment, the optical reflection properties comprise values of a reduced luminance coefficient r for different angle values as detailed below. This data is organized in a table, or matrix, called an r-table.

[0053] As explained below, the management system is configured to find optical reflection characteristics of a traffic lane. In particular, the management system makes it possible to estimate a table-r, denoted Trest, of the traffic lane from a luminance image Lmes of the zone 11 of the traffic lane 1, the image of which was acquired by an image acquisition device 3 and photometry data of the lighting sources of the lighting installation in use.

[0054] The optical reflection properties of the traffic lane can be described in the form of tables of luminance coefficients q. The luminance coefficients q directly link the illuminance E (incident light, in lux), usually called horizontal illuminance, generated by a lighting source to the luminance L (light reflected by the traffic lane in candela per m2) by the equation (I):

[0055] f Sx

[0056] The luminance coefficients q are functions of: - the angle of observation a by an observer of a point illuminated by the lighting source, a is the angle measured between the direction of observation and the horizontal plane. - the angle [3 between the plane of incidence of the light from the lighting source and the observation plane. In other words, [3 is the azimuth angle measured between two vertical planes, one containing the observation direction and the other the lighting direction. - the angle of incidence y of the light (more specifically its tangent: tan y). In other words, y is measured between the vertical and the lighting direction.

[0057] These angles are illustrated in [Fig.3].

[0058] For a standardized road area between 60 and 160 meters in front of a driver and an observation height of 1.5 meters, the variations of q as a function of the angle a are negligible and the angle a is considered to be equal to 1°. The angle a being defined, the luminance coefficient q depends on [3 and y (more particularly tan y).

[0059] For simplification, the reduced luminance coefficient r is used instead of the luminance coefficient q, according to equation (II):

[0060] . ..

[0061] k being a constant (104).

[0062] Usually [3 is sampled between 0° and 180° over 20 points, and tan y is sampled between 0 and 12 (0° <y <86°) sur 29 points. La table-r peut ainsi être présentée sous forme d’une matrice de dimension 29x20.

[0063] An example of an RI class r-table, of dimension 29x20, defined by the Commission International Illumination (CIE) is given in [Fig.5A].

[0064] Generally, optical reflection characteristics can also be presented in the form of bidirectional reflection distribution functions (BRDFs). An r-table is usually considered as a part of the bidirectional reflection distribution functions.

[0065] An r-table describes optical reflection properties of a surface, such as a traffic lane, in the form of a matrix. The r-table relates the incident light, also usually called horizontal illuminance, produced by a lighting source, to the light reflected (the luminance) by the illuminated surface towards the eye of an observer, for example a driver, for a given viewing angle.

[0066] Knowing the distribution of the luminous intensity of a lighting source or of a set of lighting sources, that is to say the luminous intensity emitted in different directions or angles by the lighting source or the set of lighting sources for a given power supply (power, voltage and / or intensity), and its location (position in space), which corresponds to a given photometry as detailed below, it is possible to calculate the luminance (reflected luminous intensity) of the illuminated zone of the traffic lane and to deduce therefrom criteria of lighting quality of the traffic lane linked to its clarity (average luminance of the road) and its homogeneity (general and longitudinal uniformities).

[0067] R-table standards have been defined by the International Commission on Illumination (CIE).

[0068] On the basis of a statistical study of the photometric characteristics of road surfaces, the CIE has defined different classes of surfaces, depending on the value of the specularity coefficient SI, namely: - classes C, R, N which represent standard coatings for a dry surface condition, and - W classes which represent standard coatings for a wet surface condition.

[0069] The skilled person thus has access to examples of reference (or standard) table-r in the document "CIE 144:2001 Road surface and road marking reflection characteristics standard by Commission Internationale de L'Eclairage, 01 / 01 / 2001" ISBN(s):9783901906121, for example available at the following address: https: / / www.techstreet.com / cie / standards / cie-144-2001 ?product_id= 1210062

[0070] The r-tables defined by the CIE and noted R1-R4, C1-C2, N1-N4 and W1-W4 are presented in Figures 5A - 5N.

[0071] The International Commission on Illumination (CIE) has defined Q0 lightness and SI specularity coefficients to summarize the reflectance power of road surfaces. The QO clarity and S1 specularity coefficients are deduced from the luminance coefficient measurements.

[0072] A coating reflects light according to a pattern where both specular components (mirror effect) and diffuse components contribute.

[0073] The average luminance coefficient QO describes the clarity of the coating. The specularity coefficient S1 describes the specular character of the coating:

[0074] where Q is the solid angle containing all directions of incident light.

[0075] The reference r-tables can be differentiated from each other by these coefficients Q0 and SL

[0076] Light fixture

[0077] In the example illustrated in the figures, the lighting installation 2 comprises several luminaires 20. The description also applies to the case where the lighting installation comprises a single luminaire 20.

[0078] The luminaires 20 are arranged to illuminate the traffic lane 1. The traffic lane may also be called a roadway, road, etc. The traffic lane may also be composed of several traffic lanes. Usually, the traffic lane may be traveled by pedestrians, cyclists and / or drivers of motorized vehicles such as cars.

[0079] Each luminaire 20 comprises a support structure, such as a mast, and lighting sources carried by the mast. The lighting sources comprise at least two lighting sources whose power supply can be controlled to allow the emitted light intensity value of each lighting source (i.e. the incident intensity or lighting) to be varied.

[0080] In the example illustrated in the figures, each lighting source is an LED, but the description also applies to other lighting sources whose power supply is controllable, such as plasma lighting sources. By modifying the power supply of the lighting source it is possible to modify the light intensity emitted by the lighting source.

[0081] According to a particular aspect, the luminaire includes a device such as an electronic module for controlling the power supply of the LEDs (also called a driver in English). The lighting sources may be associated with optics, such as lenses for the LEDs. It may be provided that the luminaire comprises one optic per lighting source or per group of lighting sources.

[0082] Photometry

[0083] Each luminaire 20 is associated with a plurality of photometries. In the example illustrated in [Fig.l], a first photometry 201 and a second photometry 202 have been schematized for a given luminaire 20.

[0084] Each photometry is defined by: - an LED or a set of LEDs, i.e. one or more LEDs, the position of the LED or set of LEDs being known relative to the area of the illuminated traffic lane whose image is acquired by the image acquisition device; (Each corresponding LED or set of LEDs is identified) - a luminous intensity value emitted by the LED or set of LEDs for different directions, i.e. for different emission angles (centered on the position of the corresponding LED or set of LEDs). Each direction is associated with a luminous intensity value.

[0085] A set of LEDs of a photometry can be considered as a point source. In the remainder of the description, reference is made to photometries defined with a set of LEDs, but the description also applies to the case of photometries defined with a single LED.

[0086] According to one embodiment, said luminous intensity value is a relative luminous intensity value in candela per kilo lumen (cd / khn), i.e. the luminous intensity emitted by the LED assembly for 1000 lumens. The processing unit 100, presented below, may comprise a photometry file which gives, for different combinations of angle value noted C (from 0 to 360°), and angle values y (from 0 to 180°), the luminous intensity that the LED assembly can emit for 1000 lumens (cd / klm) in the direction corresponding to this combination of angles. The angle C (not shown) is the angle that, in projection in a horizontal plane, the emission direction (direction of incidence) makes with a reference axis in said horizontal plane.

[0087] For a given angle / direction, the light intensity emitted by the LED assembly depends on the electrical power supply (intensity) supplied to it. For example, a photometry LED assembly may be configured to emit 100 kilo lumens when said LED assembly is supplied with maximum operating electrical power. It is then possible to obtain a desired light intensity for a given photometry by adapting the power (voltage and / or intensity) supplied to the photometry LED assembly which makes it possible to achieve this desired light intensity.

[0088] It can be provided that the position of each LED and the area to be illuminated is known in the terrestrial reference frame.

[0089] It can be provided that a part of the LEDs of a photometry is common to another photometry of this luminaire.

[0090] In the following description each photometry comprises a group of LEDs, but the description also applies to the case where a photometry comprises a single LED or other controllable lighting source whose power supply is controllable.

[0091] The LEDs of one photometry can be powered independently of the LEDs of another photometry of the luminaire. Thus, it is possible to switch off the LEDs of one photometry and switch on the LEDs of another photometry.

[0092] By way of example, the first photometry 201 comprises 48 LEDs and the second photometry 202 comprises 48 other LEDs which can be controlled independently of the 48 LEDs of the first photometry.

[0093] It is also possible to provide for applying a given percentage of the total light intensity, for example 80%, of a first photometry 201 and applying a different percentage to the other photometry 202. The percentage can be applied to the number of lit LEDs of the photometry.

[0094] It is also possible to provide for applying a given power (or intensity or current) to a group of LEDs and another power (or intensity or current) to another group of LEDs.

[0095] Different combinations of control of LEDs of different photometries can also be implemented. The different photometries available for each luminaire and the different possible combinations of these photometries within the same luminaire and / or for several luminaires, associated with different electrical powers, voltages or intensities, which can be applied to the lighting sources of said photometries or combination of photometries, form as many different lighting situations, also called scenarios.

[0096] The positioning geometry of the luminaires and the lighting sources of the installation relative to the traffic lane is known to the management system. Corresponding position data can thus be stored in a memory of a processing unit 100 presented below. In particular, the management system knows the position in space relative to the traffic lane 1 of the lighting source assemblies of the photometries of the luminaires.

[0097] According to one embodiment, each luminaire comprises a module (or device) for controlling the lighting LEDs that the luminaire incorporates. The control module makes it possible to control the power supply of the LEDs (power, voltage and / or intensity). The control module makes it possible to control a different power supply for each LED or group of LEDs in order to be able to adjust the intensity of the luminous flux of the luminaire and preferably the spatial distribution (and therefore the homogeneity or uniformity) of the luminous flux of the luminaire.

[0098] The use of LEDs as lighting sources for luminaires makes it possible to modulate the lighting effectively, both in quantity (total outgoing flux) and in spatial distribution on the traffic lane (uniformities). The LED luminaire(s) may be associated with sensors, such as user detection sensors so that the management system can be configured to control the lighting source of the or each luminaire based on data provided by one or more sensors.

[0099] Image acquisition device

[0100] The management system comprises an image acquisition device 3. The image acquisition device 3 makes it possible to acquire an image of the zone 11 of the traffic lane 1 and to generate a corresponding luminance image Lmes (cd / m2).

[0101] For this purpose, the image acquisition device 3 is previously calibrated in luminance on an optical bench in the laboratory to provide, for one or different settings of the image acquisition device 3, the correspondence between the different gray level values that the points of an acquired image can take and luminance values.

[0102] Calibration is performed by determining the parameters of an equation that relates the gray level values to the luminance values. The equation can be of the type y = Ax + B, with y the luminance value, x the gray level value, and A and B the parameters to be calculated.

[0103] The points of the image correspond to the area of the track from which the image was acquired and the luminance image corresponds to the set of luminance values (reflected light intensity) associated with the different points.

[0104] In the representation of the Lmes image in [Fig.l], the graduation of the abscissa axis and the graduation of the ordinate axis correspond to coordinates of the points (luminance measurement points) of the imaged area of the imaged traffic lane. The color scale to the right of the image indicates a luminance level (candela / m2).

[0105] The image acquisition device can thus provide luminance images, also called measured luminance maps. Preferably, the luminance of the traffic lane illuminated by the luminaires 20 of the lighting installation 2 is measured continuously.

[0106] As detailed below, the luminance map Lmesobtained is then analyzed as a function of the photometric data and the position of each luminaire 20 to determine a table-r of the zone 11 of the traffic lane 1 illuminated by the lighting installation.

[0107] As recalled above, the management system comprises a processing unit 100. The processing unit 100 comprises a memory in which photometry data for each luminaire are stored.

[0108] The processing unit 100 also comprises a module 4 for determining optical reflection characteristics. In the example illustrated in the figures, the module 4 for determining optical reflection characteristics is a module for determining table-r which allows to construct (generate) a table-r representative of the optical properties of a zone 11 of the traffic lane 1 lit by the lighting installation, as explained below.

[0109] The table-r determination module 4 is configured to determine, preferably in real time, the table-r of the zone 11 of the traffic lane, and this as a function of the photometry data during use of the luminaires, and of the luminance image Lmesmeasured.

[0110] As recalled above, the processing unit 100 also comprises a control module 6 configured to transmit instructions to the luminaires of the lighting installation to control associated lighting source assemblies.

[0111] The processing unit 100 and in particular the table-r determination module 4 presented below has access to the photometry data with which the luminaires 20 are operating.

[0112] The photometric data with which each luminaire is currently operating can be determined from the instructions of the control module 6 transmitted to the luminaires.

[0113] Virtual table-r

[0114] The processing unit 100 comprises a base of r-tables, called virtual r-tables, which are formed from reference r-tables, already known, by applying to these reference r-tables a principal component analysis as explained below.

[0115] For example, the reference r-tables can be chosen from reference r-tables defined by the CIE. A person skilled in the art has access to reference r-tables, for example, in the publication “CIE 144:2001 Road surface and road marking re-flection characteristics standard by Commission Internationale de L'Eclairage, 01 / 01 / 2001”, such as the reference tables usually denoted Cl, C2, R1..R4, N1..N4, W1..W4.

[0116] According to one embodiment, it may be provided to take experimentally measured tables as a reference table.

[0117] According to one embodiment, the reference r-tables comprise 14 r-tables, defined by the CIE and provided in Figures 5A-5N.

[0118] The reference r-tables 1010 may comprise tables previously measured actually or resulting from an average of measured tables. The reference r-tables used to form the virtual r-tables may also comprise experimental r-tables for example measured with a gonioreflectometer.

[0119] The reference r-tables present different values of clarity coefficient Q0 and specularity coefficient SL

[0120] As illustrated in [Fig.2], the r-table generation module 4 is configured to apply a principal component analysis (PCA) to a plurality of r-tables of reference 1010.

[0121] The principal component analysis of these reference tables 1010 makes it possible to obtain virtual tables 1020, also called eigenvectors rvb rv2,..., rvD. For example, it is possible to obtain ten virtual r-tables.

[0122] PCA is a dimensionality reduction method that can be used to reduce the dimensionality of large data sets, by transforming a large set of variables into a smaller one that still contains the majority of the information of the large set.

[0123] Preferably, according to a first step of standardization of the extent of the initial variables, the average of each variable (or parameter) is subtracted from said variable, so that each of the variables contributes equally to the analysis.

[0124] Next, a covariance matrix is calculated to identify the correlations. The eigenvectors and eigenvalues of the covariance matrix are calculated using a singular value decomposition (SVD) algorithm to identify the principal components.

[0125] By ranking the eigenvectors in order of their eigenvalues, from highest to lowest, the principal components are obtained in order of importance.

[0126] Organizing information into principal components in this way allows dimensionality to be reduced without losing much information.

[0127] In the example illustrated in the figures, the objective is to reduce the dimensionality 580 (corresponding to the dimension 29x20 of each r-table) in order to more easily solve a linear system containing a number of equations corresponding to the number of points NG of the luminance image.

[0128] The dimensionality of the space can be chosen arbitrarily or by referring to an r-table reconstruction error, by calculating the relative root mean square error (RRMSE) by the formula: RRMSE (%) = 100. j ' '

[0129] with Rri the non-zero element i of a reconstructed r-table using the weighting coefficients Xi,X2„ XD resulting from the principal component analysis and the decomposition of the luminance map on the virtual luminance maps according to the method detailed below,

[0130] King the non-zero element i of one of the reference tables, noted Ro,

[0131] N the number of unaffected elements in the reference table Ro.

[0132] An RRMSE value is obtained for each reference r-table and for each dimensionality of the space. The median of the RRMSE error is plotted as shown for example in [Fig.4].

[0133] To have a high precision describing the r-table to be reconstructed, a number D of eigenvectors is kept, for example D = 10, corresponding to a number of vectors for which the median of RRMSE reaches a plateau. D is an integer greater than 0.

[0134] The basic function space can thus have a dimensionality fixed at 10. This means that a table-r of an area of any traffic lane can be represented in a space D = 10 dimensions while maintaining high precision.

[0135] Alternatively, one can also choose a default dimension value D.

[0136] A table-r can thus be decomposed on a basis of eigenvectors according to the equation:

[0137] R = Xirvi + X2rv2 + ... + XDrvD Xb..., XD being weighting coefficients rvi.. .rvD being the virtual r-tables (eigenvectors)

[0138] An example of virtual r-tables rvi and rv2 is given in [Fig.6A] and [Fig.6B].

[0139] Illuminance and Luminance

[0140] For a lighting source light intensity I, and a point P of the traffic lane at a position p, a horizontal illumination map can be calculated with the following equation (III):

[0141] . ... 1 r* s—J * -L ï — .1 ■

[0142] where Ep is the total horizontal illumination at point P, Ns is the number of lighting sources considered for the calculation, EijP are the elementary illuminations due to each lighting source separately at point P, Yi>p is the angle of incidence of the ith light source at point P and h is the mounting height of the luminaires.

[0143] The lighting source intensity I and the associated angle are derived from the photometry data with which the luminaires of the installation are currently operating.

[0144] Table-r relates the illumination E of the surface of the traffic lane to the luminance L at point P by the following equation (IV):

[0145] 1 v J — — V * .....-r............

[0146] where Lp is the luminance at point P, rijP are the reduced luminance coefficients, Ei>p are the elementary illuminations calculated from equation (III), k is a constant (104)

[0147] Luminance map base

[0148] Equation (IV) can thus be applied, for each virtual r-table (to which the terms ri>p correspond), to the lighting configuration of the lighting installation during operation, i.e. by using, for each point P of the zone of the traffic lane of which the image is acquired, values of intensity of lighting source I and angle associated therewith, for Ns lighting sources, resulting from the photometry or the combination of photometry with which the lighting installation is during operation.

[0149] For each virtual table-r, obtaining the LP value for each point P of said set of points P of the traffic lane makes it possible to obtain a virtual luminance map Lv. We thus obtain D=10 virtual luminance maps.

[0150] The set of points P forms a map or grid of NG points. NG is for example equal to 60. Said points P are surface points of zone 11 of the traffic lane of which the image is acquired.

[0151] Thus, the D virtual r-tables make it possible to obtain D luminance maps Lvb Lv2, ..., LvD, called virtual luminance maps (or also called clean maps), which thus form a base of virtual luminance maps as illustrated in [Fig.2]. The set of luminance maps is noted 1030 in [Fig.2].

[0152] A virtual luminance map is thus presented in the form of a matrix of the same size as the measured luminance map but whose values have no physical meaning (and can be negative). As explained below, each proper luminance map is associated with a principal component of the virtual table-r database and serves as a basis for decomposing a measured luminance map.

[0153] An example of virtual luminance maps Lvi and Lv2 is given in [Fig.7A] and [Fig.7B].

[0154] Decomposition of the measured luminance map LmP, on the virtual luminance maps L^, L^, .... L^n

[0155] The table-r determination module 4 decomposes the measured luminance map Lmes (to which corresponds points P of luminance value Lp mes), on the generated virtual luminance maps Lvb Lv2,..., LvD, so as to obtain coefficients Xi X2 XD associated with the generated virtual luminance maps Lvb Lv2,..., LvD which correspond to the following system of equations (V) defined for the points P of the image:

[0156] Lp mes Lp_vi+ X2 Lp_v2 ...+Xd Lp_vD

[0157] with Lp vi the luminance of point P of the virtual luminance map no. i, and i ranging from 1 to D.

[0158] These coefficients Xi X2 ...XD are obtained by solving the system of equations (V) below above: each measured luminance point Lpmescorresponds to an equation. There are therefore as many equations as there are measurement points.

[0159] The system of equations can be solved by the least squares method. This method determines the best linear combination of the generated virtual luminance maps Lvb Lv2, ..., LvD to best approximate the measured luminance map Lmeset to provide the corresponding coefficients XiX2„ XD

[0160] Estimation of the r-table from the determined coefficients

[0161] Module 4 for determining table-r makes it possible to generate an estimated table-r, noted Trest, of zone 11 of traffic lane 1 as a function of the coefficients Xi X2 ...XD obtained, according to equation (VI):

[0162] Trest= X^^ + X2rv2 ...+ XDrvD

[0163] [Fig.8] gives an example of an estimated r-table Trestobtenue with coefficients Xi X 2 XD of values:

[0164]

[0165]

[0166]

[0167]

[0168]

[0169]

[0170]

[0171]

[0172]

[0173] X1= -0.026611919 X2 = 0.528818935 X3= -0.183384405 X4 = 0.036971762 X5 = -0.040579723 X6 = -0.018550646 X7 = 0.017182181 X8 = -0.016625876 X9 = -0.008145728 X10 = -0.009002147

[0174] In this way, the method makes it possible to determine the optical reflection properties of the traffic lane using the luminaires, without the need to install specific additional luminaires.

[0175] The estimated table-r Trest thus generated is used by the control module 6 of the lighting installation 2 to generate instructions C62 to the luminaires 20, as a function of reference luminance characteristics 21 desired for the zone 11 of the traffic lane 1, in order to obtain an adapted adjustment of the lighting sources of each luminaire.

[0176] Lighting control

[0177] The control module 6 makes it possible to control the luminaires, using the data from the determined Trest table-r and the measured luminance map Lmes, to obtain luminance characteristics, which preferably include an average luminance value and uniformity values (longitudinal and general), which best approximate reference luminance characteristics, which result for example from normative requirements.

[0178] The reference (or desired) luminance characteristics may depend on the type of channel (also called class).

[0179] Thus for the traffic lane illustrated in the figures, it is desirable to obtain an average luminance value of zone 11 at least equal to a given minimum value, and with a homogeneity (homogeneity) of the luminance values associated with the points P of zone 11: it is desirable to obtain the most homogeneous (uniform) distribution of the luminance values on the points P of zone 11.

[0180] Homogeneity (or uniformity) includes a general uniformity criterion Uo and a longitudinal uniformity criterion Ub. General uniformity is given as the ratio of the minimum luminance among the luminance values at points P to the average luminance of the luminance values at points P. Longitudinal uniformity is given as the ratio of the minimum luminance to the maximum luminance among the luminance values of points P located in the middle of the traffic lane.

[0181] An example of reference luminance characteristics is given below for different classes (or types) of traffic lanes. These reference luminance characteristics correspond to the minimum values of average luminance £, general uniformity Uo and longitudinal uniformity Ui to be achieved for different classes Ml - M6 corresponding to different types of lane.

[0182] ] us | ] Mi $LS®? : IO® $ a ; XL > î Wü J 0® 0 U | OÔ M6 O® O® WW . . . ..X. . . . ... . . ... . . . . . . . 1

[0183] A traffic lane of type Ml is a lane which requires a greater minimum luminance value than a lane of type M2... or M6. A lane of type Ml can thus be a motorway, and conversely a lane of type M6 can be a pedestrian lane.

[0184] Thus, according to one embodiment, the processing unit 100 comprises in memory reference characteristics corresponding to the type of lane of the traffic lane whose image is acquired. It can be provided that the processing unit comprises several sets of reference characteristics for different types of lane, and that an interface allows an operator to enter the type of lane whose acquired image to enable the processing unit to select the reference characteristics associated with the type of track indicated by the operator. Alternatively, the reference characteristics may be predefined in the processing unit taking into account the type of track for which the processing unit is intended to be used.

[0185] The control module simulates, from all the available photometries and combinations thereof, and for different power supply values of the LEDs of the photometries, different lighting configurations giving different lighting values Ep for each point P of the zone 11 of the traffic lane.

[0186] For each simulated lighting configuration, the control module 6 calculates, from the calculated Ep values, and from the estimated r-table previously generated by the r-table determination module 4, an estimated luminance map Lest.

[0187] The control module 6 calculates, for each estimated luminance map Lest, the average luminance value and one or more uniformities of the luminance values on the points P of the zone 11, and identifies the estimated luminance map Lest, for which the average luminance value and the uniformities of the luminance values on the points P of the zone 11 come closest to the reference luminance value and the reference uniformity or uniformities for the traffic lane 1. The type of lane (M1, M2,... or M6) is stored in the processing unit so that the control module knows the reference characteristics to be used to carry out the comparison operation.

[0188] The control module 6 identifies from said identified estimated luminance map Lest, the photometry or the combination of photometries, with the associated power supply of the LEDs, which made it possible to obtain said identified estimated luminance map Lest. The control module 6 then transmits to the luminaires instructions for the activation of said identified photometry, or combination of photometries, with the associated power supply of the LEDs.

[0189] It can be provided that the instructions from the control module 6 are transmitted to the control modules (also called "drivers" in English) of the lighting sources of the luminaires to activate the photometry or combination of photometry identified with the associated power supply.

[0190] From the instructions issued by the control module 6, the processing unit can determine the photometry or the combination of photometry of the luminaire(s) which is in use as being that resulting from the instructions issued by the control module 6.

[0191] The lighting of each luminaire can thus be controlled to tend towards an optimal setting taking into account the characteristics of the estimated table-r. The lighting provided by each luminaire can thus be adapted to the surface condition of the traffic lane, for example dry or wet.

[0192] As recalled above, it can be provided that the r-table determination module 4 generates the r-table of the zone 11 of the traffic lane 1 for different observation angles of said zone 11. The lighting of each luminaire can then also be controlled according to the type of user, in particular pedestrian, cyclist or motorist who is traveling on the traffic lane by selecting an estimated r-table which has been calculated for a given angle corresponding to the type of user detected. Different r-tables can thus be estimated according to the type of users considered, that is to say for different observation angles.

[0193] The control module 6 can thus receive as an input parameter, for example supplied by a presence sensor, the type of user traveling on the road, with which a given observation angle is associated, for example 1° for a car, and 10° for a pedestrian, and control the luminaires 20 as a function of the generated table-r whose associated observation angle corresponds to the identified type of user.

[0194] The image acquisition device 3 is positioned relative to the traffic lane 1 so as to offer a given observation angle corresponding to the observation angle of a type of user of the traffic lane, for example a car. It may be provided that the image acquisition device 3 is movable to acquire the image according to another observation angle corresponding to another type of user. Since an r-table is calculated for a given viewing angle, it may be provided that the image acquisition device is movable according to different orientations to obtain luminance images according to different angles and thus obtain r-tables for different angles.It can also be provided that the optical characteristics of the image acquisition device make it possible to acquire images for several different observation angles at the same time, for example for an observation angle of 10° for a zone 11 which would be located at the bottom of the image and simultaneously for an observation angle of 1° for a zone 11 which would be located in the middle of the image.

[0195] The processing unit 100 makes it possible to adapt the lighting scenario implemented (i.e. the instructions) according to the optical reflection properties of the surface of the traffic lane (which may vary over the years and according to weather conditions) due to the presence in the luminaires of several distinct photometries, for example one dedicated to a dry coating, the other to a wet coating. Thus, depending on the surface condition of the traffic lane, the control module 6 of the processing unit 100 makes it possible to implement a lighting scenario (i.e. a set of instructions) mobilizing one or other of the photometries as well as a set of linear combinations between them.

[0196] Other aspects

[0197] The system may comprise a control cabinet for the lighting installation housing the processing unit 100. Alternatively, the processing unit may be housed at the level of a supervisor system or directly in the imaging system, i.e. the image acquisition device, which may then form a smart camera.

[0198] The processing unit is presented for example in the form of a processor and a data memory in which computer instructions executable by said processor are stored, or in the form of a microcontroller.

[0199] In other words, the functions and steps described can be implemented in the form of a computer program or via hardware components (e.g. programmable gate arrays). In particular, the functions and steps operated by the processing unit can be performed by instruction sets or computer modules implemented in a processor or controller or be performed by dedicated electronic components or components of the programmable logic circuit type (or FPGA which is the acronym for field-programmable gate array, which literally corresponds to in-situ programmable gate array) or of the application-specific integrated circuit type (or ASIC which is the acronym for application-specific integrated circuit, which literally corresponds to application-specific integrated circuit). It is also possible to combine computer parts and electronic parts.

[0200] The processing unit is thus an electronic and / or computer unit. When it is specified that said unit is configured to carry out a given operation, this means that the unit comprises computer instructions and the corresponding execution means which make it possible to carry out said operation and / or that the unit comprises corresponding electronic components.

[0201] The invention is not limited to the embodiments illustrated in the drawings.

[0202] Furthermore, the term "comprising" does not exclude other elements or steps. Furthermore, features or steps that have been described with reference to one of the embodiments set forth above may also be used in combination with other features or steps of other embodiments set forth above.

Claims

1. Claims System for managing a lighting installation (2) arranged to illuminate a traffic lane (1), the lighting installation comprising a plurality of lighting sources whose electrical power supply is controllable, the management system comprising: - an image acquisition device (3) for generating a luminance image (Lmes), called a luminance map, of an area (11) of the traffic lane (1); and - a data processing unit (100), the system being characterized in that said processing unit (100) comprises: - several photometries (201, 202) of the lighting installation (2), each photometry being defined by a lighting source or a set of lighting sources forming part of said plurality of lighting sources of the lighting installation (2), and light intensity values that the lighting source or the set of lighting sources is capable of emitting in different directions; - a module (4) for determining a set of optical reflection characteristics configured to determine a set of optical reflection characteristics of the traffic lane, as a function of the acquired luminance image (Lmes), of at least part of the photometries of the lighting installation (2), and of positioning data, such as the height, of the lighting source(s) of said photometries relative to the zone (11) of the traffic lane (1); and - a control module (6) configured to control at least part of the lighting sources of the lighting installation (2), as a function of the determined optical reflection characteristics, of at least part of the photometries of the lighting installation (2), and of reference luminance characteristics; - the module (4) for determining a set of optical reflection characteristics being configured to determine a set of optical reflection characteristics of the traffic lane (1) by executing at least the following steps: - principal component analysis of sets of reference optical reflection characteristics (1010) to generate sets of virtual optical reflection characteristics, also called vectors own rgb rv2,..., rvD (1020); - generation of several virtual luminance maps Lvb Lv2,..., LvD (1030), as a function of: the eigenvectors rgb rv2,..., rvD, the positioning data of the lighting sources of the lighting installation (2), relative to the zone (11) of the traffic lane (1), and the photometry data during use of the lighting installation (2); - decomposition of the luminance map (Lmes) provided by the image acquisition device, on the virtual luminance maps Lvb Lv2,..., LvD, so as to obtain coefficients XbX2 XD associated with the virtual luminance maps; and - determination of the set of optical reflection characteristics of the traffic lane (1) by linear combination of the eigenvectors r vb rv2,..., rvD with the coefficients XbX2 XD obtained.

2. System according to claim 1, in which the control module (6) is configured to: - define a plurality of lighting scenarios, each scenario comprising the following definition parameters: a photometry or a combination of photometries chosen from the photometries of the lighting installation (2), and one or more data relating to the electrical power supply of the lighting source(s) of the photometry or combination of photometries chosen; - determine for each scenario, from the determined optical reflection characteristics of the traffic lane, the luminance characteristics of the traffic lane when said traffic lane is illuminated according to the definition parameters of said scenario, and - compare for each scenario the determined luminance characteristics of the traffic lane with the reference luminance characteristics; - identify the scenario for which the determined luminance characteristics are closest to the reference luminance characteristics; - control the lighting sources of the lighting installation (2) which correspond to the identified scenario, according to the electrical power supply data used in the identified scenario.

3. A system according to claim 1 or 2, wherein the sets of optical reflection characteristics are r-tables, each r-table comprising values of a reduced luminance coefficient, denoted r, defined according to the equation: F — £ . fj)* with k a constant, and q a luminance coefficient defined by: O ' F with E the horizontal illumination generated by a lighting source, and L the luminance, q being a function of: - the angle of observation a, - the angle [3 between the plane of incidence of the light of the lighting source and the plane of observation, and - the angle of incidence y of the light, the table-r including values of r for different values of angle [3 and different values of tan y.

4. The system of claim 3, wherein the sets of reference optical reflection characteristics being reference r-tables, said reference r-tables comprise r-tables which have torque values {QO; SI} different from each other, with: QO TU q 4a SI -et - y 1 where Q is the solid angle containing all directions of the incident light.

5. System according to any one of claims 3 to 4, wherein the sets of reference optical reflection characteristics comprising: - reference r-tables of class RI, R2, R3, R4, Cl, C2, NI, N2, N2, N4, Wl, W2, W3, and / or W4, and / or - experimentally measured r-tables.

6. System according to any one of claims 3 to 5, in which the sets of virtual optical reflection characteristics are virtual r-tables, and in which, for the generation of several virtual luminance maps Lvi, Lv2,..., LvD (1030), also called eigenmaps, the determination module (4) is configured to apply, for each virtual table-r, and for each point P of the area of the traffic lane of which the image is acquired, the equation: I ...... j to the lighting configuration of the lighting installation in operation, where Ns is the number of lighting sources considered for the calculation, YiP is the angle of incidence of the ith lighting source at point P, k is a constant, Lp is the luminance at point P, ripsont the reduced luminance coefficients of a virtual table, Eipsont the elementary illuminations due to each lighting source separately at point P, calculated from the equation: ...... îx- where h is the height of the lighting source, I is the intensity emitted by the ith lighting source of the lighting installation in the direction of point P.

7. A system according to any preceding claim, wherein the or each lighting source comprises one or more LEDs.

8. System according to any one of the preceding claims, in which the lighting installation (2) comprises several luminaires, each luminaire comprising a part of said lighting sources of the lighting installation (2), each luminaire comprising a device for controlling the power supply of the lighting sources of the luminaire.

9. A system according to any preceding claim, wherein the reference luminance characteristics comprise at least one of the following characteristics: - the minimum average luminance of the taxiway; - the general uniformity in minimum luminance of the taxiway; and - the longitudinal uniformity in minimum luminance of the taxiway.

10. A system according to any preceding claim, taken in combination with claim 3, wherein the module (4) of determination of a set of optical reflection characteristics is configured to determine several r-tables of the traffic lane according to several types of user able to circulate on said traffic lane to which are associated different observation angles of the traffic lane, the control module (6) being configured for, for a specific type of user traveling on the traffic lane: - select the determined table-r whose associated observation angle corresponds to the determined user type, and - control at least part of the lighting sources of the lighting installation (2), using the selected determined table-r.

11. Method for managing at least one lighting installation (2) arranged to illuminate a traffic lane (1), the lighting installation having several photometries (201, 202), each photometry being defined by: - a lighting source or a set of lighting sources of the lighting installation (2), and - light intensity values that the lighting source or said set of lighting sources is capable of emitting in different directions; the method comprising acquiring an image (Lmes) of an area (11) of the traffic lane (1) to generate a luminance image of this area (11); characterized in that the method comprises the following steps: - determination of a set of optical reflection characteristics of the zone (11) of the traffic lane (1) as a function of: the acquired luminance image (Lmes); of at least part of the photometries (201, 202) of the lighting installation (2); positioning data, such as the height, of the lighting source(s) of said photometries relative to the area (11) of the traffic lane (1); and - control of at least part of the lighting sources of the lighting installation (2), as a function of: determined optical reflection characteristics, at least part of the photometries of the lighting installation (2); reference luminance characteristics, the step of determining a set of optical reflection characteristics of the traffic lane (1) comprising at least the following steps: - principal component analysis of sets of reference optical reflection characteristics (1010) to generate sets of virtual optical reflection characteristics, also called eigenvectors rgb rv2,..., rvD (1020); - generation of several virtual luminance maps Lvb Lv2,..., LvD (1030), as a function of: the eigenvectors rgb rv2,..., rvD, the positioning data of the lighting sources of the lighting installation (2), relative to the zone (11) of the traffic lane (1), and the photometry data during use of the lighting installation (2); - decomposition of the luminance map (Lmes) provided by the image acquisition device, on the virtual luminance maps Lvb Lv2,..., LvD, so as to obtain coefficients XbX2...XD associated with the virtual luminance maps; and - determination of the set of optical reflection characteristics of the traffic lane (1) by linear combination of the eigenvectors r vb rv2,..., rvD with the coefficients XbX2...XD obtained.

12. A method according to claim 11, wherein the step of controlling the lighting sources is carried out also as a function of a type of user traveling on the traffic lane.

Images