TECHNICAL FIELD

The present disclosure relates to control of illumination, and particularly but not exclusively to control of lighting in public spaces, via outdoor lighting networks (OLNs). BACKGROUND

Systems have been introduced for the management of an outdoor lighting network (OLN). For example, lighting units of an OLN may be remotely managed to provide control over lighting behaviour (e.g., scheduling of the on/off times of the lighting units and/or setting dimming levels of the lighting units). Management of outdoor lighting networks may provide one or more benefits to customers (e.g., municipalities) such as energy savings, reduced maintenance costs, and/or reduced lighting pollution, etc.

Increased intelligence and flexibility in lighting systems and networks allow more sophisticated control, and management of a lighting network may involve receiving information from one or more sensors, such as traffic information or ambient lighting, and processing such information to control the output from one or more lighting units such as streetlights for example. Such lighting units can be controlled locally, in groups or individually in some cases.

Such systems can advantageously respond to specific events to provide lighting suitable for that event. For example if an event such as a traffic accident or public disturbance requires the presence of emergency services, or a ruptured water main requires the attention of a maintenance crew, appropriate lighting can be provided to allow the relevant parties better to perform their job.

SUMMARY

It has been found that while providing specific lighting for an event can assist the relevant parties to that event (e.g. police or maintenance crew), if that localised lighting is significantly different to the adjacent or default lighting, then unwanted attention may be drawn to that event, e.g. from passers by. Accordingly, in one aspect of the present invention there is provided a method of controlling a lighting system, said system including a plurality of lighting units distributed in an area to be illuminated, said lighting system including background light output settings for said lighting units, said method comprising receiving a trigger indicative of an event occurring at a specified location in said area; determining a lighting modulation profile in response to said received trigger, said modulation profile defining a target light output at said specified location, and defining a graded transition from said target light output at said target position to a default light output over a transition region; obtaining the relative positions of a set of said lighting units relative to said specified location; mapping said modulation profile onto said set of lighting units to determine modulated light outputs for said set of lighting units, said mapping based on the obtained relative positions, the determined modulation pattern, and the background light output; and driving said lighting units to achieve said modulated light outputs.

By transitioning lighting from a desired or target output at the location of the event, to a background level at a distance away from the event, the change in lighting, or difference between the background lighting and the target is less noticeable, and this may reduce the amount of unwanted attention. In other words, the difference between adjacent lighting units is within a predetermined range. For example, the predetermined range can be a relative range such that the difference in light level between adjacent lighting units is no more than e.g. 10% (e.g. of the target level or the lowest/highest light level of the adjacent units) or the color difference is no more than e.g. half the distance in x,y color space between the color of the background light output and the color of the target light output. As another example, the predetermine range is set to e.g. 100 lumen.

In embodiments, the lighting modulation profile may be determined based on the specified location, and/or the positioning or spatial arrangement of lighting units in the vicinity of the specified location. For example a particular profile may not be possible, because of the number, position or output capabilities of lighting units present. Account may also be taken of lighting units which have failed, or which have a technical issue affecting light output. More generally, the lighting modulation profile may be determined based on local geography or landscape, including factors such as roads and buildings.

The lighting modulation profile may additionally or alternatively be based on the type or nature of the event, or human behaviours related to the event. Examples of such behaviours include the number and location of people in a given area, movement of people in the area, and possible specific recognisable actions of people in the area, such as speech or acts of aggression or distress.

A further factor or factors on which the modulation profile may be based is ambient factors or conditions in the environment of the lighting system and/or the event. Such factors may include the time of day, weather, or relevant laws or regulations affecting light output.

In embodiments, the lighting modulation profile defines the variation of at least one lighting parameter with distance from said specified location. Example lighting parameters include brightness, colour, saturation, direction, angle, beam shape and dynamic effect. In some cases, a single profile may define the variation of multiple parameters, for example defining a transition between a first light setting comprising a first set of parameter values and a second light setting comprising a second set of parameter values. It is also possible for multiple different profiles to be defined and used in combination for a single event if desired.

The lighting modulation profile need not be symmetrical or regular, and the transition may be different according to the azimuth or direction from an event centre point. For example the transition may have a first pattern or form east of the event, but may exhibit a different pattern or form west or north of the event. Thus in embodiments the profile can be considered as a 3D surface defining a lighting parameter or parameters as a function of 2 dimensional position, which may be expressed in Cartesian or Polar coordinates for example.

Defining the modulation profile may comprise defining an aspect of the profile, such as the target light output at the specified location. The target light output can be specified in terms of lighting parameters such as brightness and colour for example, and also the size of the area to be illuminated by the target lighting can be defined in embodiments.

Defining the modulation profile may further or alternatively comprise defining the size of the transition region in embodiments. The transition region may be considered the region from the edge of the area where the target lighting is provided, to a region where lighting is unaffected by the event. In the case that the target lighting is considered at a point, then the transition region may be considered as the total area where lighting is modulated as a result of the event. By controlling the transition region, the average gradient can be controlled, with a larger transition size typically enabling a more gradual transition. Factors noted above such as geographical/topological, behavioural and/or ambient/environmental factors may be used to determine the target light output and/or the transition region.

Selection of the set of lighting units to be used to provide the modulated light output may be based on said modulation profile and the spatial arrangement of said lighting units. In this way, the modulation profile and the lighting units to be used can effectively be determined and selected in parallel, so as to be complementary or at least compatible.

In embodiments, determining a lighting modulation profile and mapping said modulation profile onto said set of lighting units may comprise selecting one or more first light sources, based on the target light output and the location of said light sources relative to the specified location, and controlling said first light sources to provide said target light output to said target area; and selecting one or more second light sources, based on the location of said light sources relative to said first light sources, and controlling said second light sources to provide a graded light output transition from said target light output to said default light output. The selecting and controlling of the first and second light sources may be performed separately, for example by different processes or control logic, and possibly at different times, eg the second light sources being selected and controlled immediately after the first. Alternatively the first and second light sources may be selected and controlled together, in a single control operation, and substantially simultaneously.

Mapping the modulation profile onto lighting units may simply comprise determining lighting parameters from the profile based on the location of a lighting unit, and driving that lighting unit with such parameters, in some examples. This is more likely to be appropriate if the profile has been determined taking onto account the lighting units available locally to the event. However, in other cases, such a straightforward mapping may not be possible or desirable. For example a given lighting unit may not be capable of meeting the desired parameters. It will therefore be understood that one or more lighting units may be driven to approximate the lighting profile, and other lighting units may be used to

compensate, better to approximate the overall profile. In other words, a best fit approach may be adopted.

An event can be substantially any activity, matter or occurrence for which it is desired to provide a certain illumination output, pattern or effect which differs from the default or background illumination. Accordingly, in embodiments a trigger includes at least one of a user input, a sensor input or a data input from an external source. In a further aspect of the present invention there is provided a lighting system comprising a plurality of lighting units distributed in an area to be illuminated, said lighting units having a predetermined background light output; an input for receiving a trigger indicative of an event occurring at a specified location in said area; a controller adapted to determine a lighting modulation profile in response to said received trigger, said modulation profile defining a target light output at said specified location, and defining a graded transition from said target light output at said target position to a default light output over a transition region, and a memory storing the positions of said lighting units; wherein said controller is further adapted to map said modulation profile onto said set of lighting units to determine modulated light outputs for said set of lighting units, based on the positions of said lighting units, the determined modulation pattern, and the background light output, and to drive said lighting units to effect said modulated light outputs.

In some embodiments, said controller is adapted to drive each lighting unit individually, while in other embodiments, the controller is adapted to drive said lighting units in groups, via a segment controller. The controller may be distributed in embodiments, over multiple different components of said system, and may be integrated into one or more of said lighting units.

The invention also provides a computer program and a computer program product for carrying out any of the methods described herein and/or for embodying any of the apparatus features described herein, and a computer readable medium having stored thereon a program for carrying out any of the methods described herein and/or for embodying any of the apparatus features described herein.

The invention extends to methods, apparatus and/or use substantially as herein described with reference to the accompanying drawings.

Any feature in one aspect of the invention may be applied to other aspects of the invention, in any appropriate combination. In particular, features of method aspects may be applied to apparatus aspects, and vice versa.

Furthermore, features implemented in hardware may generally be implemented in software, and vice versa. Any reference to software and hardware features herein should be construed accordingly.

BRIEF DESCRIPTION OF THE DRAWINGS

Preferred features of the present invention will now be described, purely by way of example, with reference to the accompanying drawings, in which: Fig.1 is a functional block view of an example lighting system; Fig. 2 is a perspective view showing an example street environment;

Figure 3 is a schematic plan view of an area including a plurality of lighting units;

Fig. 4 shows the area of figure 3 with a lighting profile overlaid; Fig. 5 shows an example lighting profile;

Figs. 6a and 6b show a plan view and corresponding sectional profile;

Fig. 7 shows a profile mapping onto a set of lighting units;

Figs. 8a to 8c show examples of drive arrangements for a set of lighting units;

Fig. 9 illustrates an alternative approach to a profile mapping;

Fig. 10 shows an inverse profile;

Fig. 11 is a flowchart showing a method of lighting control.

DETAILED DESCRIPTION OF EMBODIMENTS

Referring to Figure 1, a lighting management or control system 100 is illustrated schematically. The lighting system, or at least the lighting units 102 thereof, may be installed in an outdoor environment such as a town or city or park, or along a road or network of roads, or an indoor space, such as a stadium, shopping centre, or apartment block for example.

A plurality of lighting units 102 are provided, which may take a wide variety of forms such as lighting poles, wall or floor mounted luminaires, spot lights etc adapted to illuminate a space or environment. The lighting units typically include one or more light emitting elements, such as LED elements or lamp elements. The lighting units are connected to a network 104 via lighting drivers or controllers 106. Each lighting unit may have a dedicated controller as in the case of controllers 106a, or alternatively a common controller may be provided for a group of lamps as in 106b. In the case of a common controller, an additional, dedicated controller or driver (not shown) may be provide for each lighting unit. A dedicated controller for a lighting unit may be integrated into the lighting unit.

Lighting drivers or controllers are able to send and receive communications signals to the network, and can use such communication signals to appropriately drive the lighting unit(s) to provide desired output illumination. Additionally or alternatively, lighting controllers may be able to communicate directly to other lighting controllers, as shown by a dashed line in Figure 1. A plurality of sensors 110 are provided, coupled to the lighting system 100 via network 104. The sensors are typically arranged in or around the environment to be illuminated by the lighting system, and can sense a wide variety of environmental or ambient conditions from electromagnetic signals to acoustic signals, to biological or chemical signals for example, for providing information about the environment and events in the environment. Examples of sensors include an IR detector, a camera, a microphone, a motion detector, a chemical sensor, a light sensor, a UV sensor, and a position sensor, although many other types of sensor are equally possible.

The system may further include one or more user control units 112 to allow a user or users to interface with the lighting system. The user control unit may be a dedicated unit such as a control panel, or user terminal, but may also be any device which is capable of acting as an interface which can communicate with the system, such as a mobile telephone, computer, tablet or smartwatch for example. Preferably the user control unit 112 provides a graphical user interface (GUI) for example on a touchscreen. In Figure 1 , the user control unit is shown as a standalone device, however it is possible for one or more such units to be integrated into other components of the system, such as a lighting unit 102, or central management system (CMS) 114 for example.

The central management system (CMS) provides control logic to control the lighting system, and in particular the output of lighting units 102, in response to a plurality of inputs, for example from sensors 110 and user control units 112, and from stored programs, settings, schedules and/or routines which may be stored in a memory 116, which may in examples be integrated with CMS 114. The CMS (and optionally memory 116) may be a single, central controller, or may be distributed, with separate units controlling groups of lighting units for example. It is even possible that the CMS is completely distributed to the lighting units themselves, in examples where some or all of the lighting units include some processing capability. Such a distributed system may further comprise a single controller for coordinating overall control for example.

The system may further include a network interface 118, for connecting the system with other networks or devices. This allows the system to exchange information with other lighting systems, which may be similar systems for example, or with networks such as the internet, or other networks related to the space or environment in which the system is located. For example, the network interface may allow the system to obtain information about traffic, weather, news, emergency services or incidents, and security, amongst others. Network 104 which allows the various components of the system 100 to communicate with each other may be a single network, or may in fact be comprised of multiple, possibly overlapping networks. The network or networks may use any wired or wireless communication protocol, or a combination of such protocols. Examples of possible protocols include Ethernet, TCP/IP, cellular or mobile communications protocols such as GSM, CDMA, GPRS, 3G, LTE etc, Wifi (such as IEEE 802.11), Bluetooth or Zigbee. Where messages or data are exchanged between two system components using a combination of protocols, a converter may be provided to convert the data or message from one protocol or format to another. In embodiments, a communication module may be provided for each component, or each communication path between components to facilitate communications.

Figure 2 is a perspective view showing an example street environment 200 including a number lighting units which may form part of the system of Figure 1 for example. Lighting units 208 are in the form of lighting poles on a pavement or sidewalk 204 adjacent a road 202. Further lighting units are provided for illuminating the environment, such as wall mounted luminaire 201 mounted on building 206, and a floor mounted luminaire 212.

Turning to Figure 3, there is shown a schematic plan view 300 of an example area or environment illuminated by a lighting system, such as the system of Figure 1, illustrating a plurality of roads 302, and the locations of a plurality of lighting units 304. An 'X' 306 designates the position of an event which has occurred or is occurring in the area. An event may be a public order incident such as a fight, or an accident or injury to a person or persons such as a traffic accident, or a maintenance issue such as a leaking pipe, for example.

Such an event may be detected or triggered by one or more sensors, such as sensors 110 of Figure 1. Another possibility is for an event to be alerted to the system by a user via a user control unit such as unit(s) 112, for example by a controller or administrator using a terminal in a control room, or by an observer or passer by via a smartphone perhaps. A further possibility is for an event to be notified or obtained from an external information source such as the internet or an emergency services control or radio network, or traffic control network, via an interface such as network interface 118 for example.

As noted, events may be classified or categorised according to defined characteristics. Such characteristics can allow events to be detected automatically. For example, threshold levels for sensed values, and combinations of sensed values can be used to determine a particular event. In the case of a video sensor, image processing and analysis can determine the number of people present in a particular area. A first event or event type could be triggered if this number reaches a first threshold value. A second type of value, for example noise, could be combined with the sensed number of people, so that a second type of event is detected if in addition the noise in that area exceeds a certain value. If a chemical detector senses a value in excess of a predefined limit, or concentration, then a corresponding type of event can be triggered.

Information about the event will typically include the location of the event, which may be a precise location, for example GPS coordinates, or a more general geographic location such as a particular zone if the relevant area is divided into such zones, or by reference to other recognizable objects or locations such as buildings or roads for example.

Figure 4 shows the same plan view as Figure 3, but with example lighting areas or templates overlayed. A first area 402 is the area immediately surrounding the location of the event X, and indicates an area for which particular event illumination is desired. A second area 404 surrounds the first area, and indicates a transition area for providing graded transition lighting as will be explained below.

The first area indicates an illumination pattern or level which is determined to be suitable in response to the event. The type of illumination and the size of the first area can be determined dynamically, and may be based on one or a number of factors including:

Geography - factors can include the location of the event or events, the relative positioning of nearby lighting units, and the surrounding

topology/landscape/infrastructure such as roads, buildings etc. For example, the nature and number of nearby light units may dictate the maximum brightness and/or colour which can be provided to the first area. This may additionally take into account light units which have suffered a failure. The availability of nearby lighting units may also influence the size of the first area. For example a larger number of lighting units may enable more light to be provided, but correspondingly increase the size. Also, a major road at or adjacent the first area may result in a need for a lower overall brightness or may make it less desirable to use certain coloured illumination (such as green or red which could be misunderstood by drivers). Also nearby lighting units may be required for other purposes, such as lighting a pedestrian crossing, and it may be considered that such units should not be used to provide event specific lighting.

Behaviours - the type or nature of the event, or persons involved in or with the event, may determine the appropriate lighting response. For example brighter or clearer lighting may be desired for emergency services attending an incident. Calming lighting may be provided if a fight or brawl has broken out. While each event may be unique, events may be categorised into a number of predetermined types or categories, to assist in selecting appropriate lighting or illumination. The number and location of individuals in or around the event may also have an influence. Smaller events involving a smaller number of people will typically require a smaller area of event specific lighting.

Ambient conditions/circumstances - the time and date, or ambient lighting may be taken into account when determining suitable event lighting. The weather may also be a relevant consideration, for example mist or fog could influence choice of lighting.

Regulations or restrictions affecting light levels may also need to be taken into account where they exist, for example to adhere to minimum or maximum lighting levels.

Although first area 402 is shown as a circle in Figure 4, it should be understood than the shape does not need to be circular or regular, and could be any shape. In many cases it may be more convenient for the first area, or equivalently the target lighting pattern or level for a given event to be considered as a point, rather than an area. Practically though, the lighting achieved at that point will be substantially uniform for at least a small area around that point, the size and extent of which will typically depend on the position and type of lighting units used to provide the target lighting.

The second area 404 allows lighting or illumination to be transitioned gradually from the target lighting of the first area (or point) to the background or default illumination of the area at or around the location of the event. The size and shape of this area can be determined taking into account some or all of the factors mentioned above, ie geography, behaviours, and ambient conditions. Illumination in this area is controlled in this example by determining the current or background lighting levels or pattern at the perimeter of the second area 404 (ie the level which would have been set if the event had not occurred) and determining a lighting profile or gradient, which transitions from this level to the target lighting at the event location, over a distance. Lighting units in this area can then be controlled based on their position and the profile or gradient determined.

Selecting or identifying lighting units for providing target lighting at the first point or area can be performed initially in examples, after which the desired lighting in the second area can be determined and effected. In such cases separate controllers, or control logic may be employed for the first and second areas. Alternatively, the process can be integrated, with a complete desired lighting profile determined in a single stage, optionally under the control of a single controller or control process, with the resulting change in lighting occurring substantially simultaneously. An example lighting profile plot is shown in Figure 5. Profile 502 is a plot of one or more light parameters on the vertical axis, against distance on the horizontal axis, centred on the location of the event "X". The parameter will often be brightness or intensity (or dimming level), but could also be another controllable parameter affecting light output. For example colour or colour temperature could be used where these can be controlled, and angle, direction and beam shape are further examples of controllable parameters in certain cases where the lighting units are capable of such control. Furthermore, combinations of such parameters may be used. In examples, different parameters could have different profiles, for the same event. The profile defines a maximum parameter value 504 representing the target lighting value discussed above in relation to first area 402. Value 504 would indicate a first point rather than a first area. As noted, the actual lighting is likely to be substantially constant over at least a small area, and therefore value 506 may be used as the target lighting value, and an associated distance 510 gives rise to a diameter (or indicative dimension) of first area 402. Thus it will be understood that by approximating the profile as flat across the distance 510, a first point 402 and associated level 504, and a first area 402 and associated level 506 may be considered equivalently for the purposes of certain examples.

A background or default level 508 is the level which it is desired to transition to. The points at the edge of the transition are separated by a distance 512, corresponding to the diameter (or dimension) of area 404. Thus the profile can be formed based on the peak or target level 504/506, background or default level 508, and the distance over which the transition is to occur. The profile can be considered as modulating the background or base lighting level which would otherwise occur. The shape of the profile can then be fitted to these points. In this case the profile is a curved, substantially normal distribution, but other types of profile or distribution are possible, including a linear profile for example. The type or shape of the profile may be selected according to geographical, behavioural, and/or background factors as discussed above.

The profile in Figure 5 can be considered as a cross section of Figure 4, but it will be appreciated that it need not be symmetrical or regular. For example, Figure 6a shows a plan view, similar to Figure 4, illustrating a profile mapped onto an area centred on an event location X. Here three boundaries are shown, which can be considered as contours of light level or light parameter value, essentially providing the profile as a 3D surface. Figure 6b shows a plot 602 of the profile of Figure 6a, in a similar fashion to Figure 5, along section 620 of Figure 6a. It can be seen that the profile is skewed, and it can also be seen that the background or default level 608 is not constant, acknowledging that prior to the event, or under normal circumstances, the default level may be different in different areas or locations. It will be understood that although only one sectional profile is shown in Figure 6b, multiple different sections could be plotted similarly, each potentially showing a different 2D profile.

Figure 7 illustrates another example of a lighting profile 702, which in this case is a linear profile, transitioning from background level 704 to peak or target level 706 at the location of an event. Here the parameter plotted is dimming level. Figure 7 also shows a plurality of lighting units 710, here in the form of light poles or lampposts. The light poles are shown at the respective distances from the origin of the event. The profile can be mapped onto the poles, to modulate their light outputs. In this case, pole 712 which is located substantially at the origin of the event is controlled to output the target lighting for the event, which is 100% dimming level (ie maximum brightness) for an example event. Other lighting units or poles, not shown in Figure 7, may also be controlled to contribute to the target lighting at the location of the event.

Although dimming level is illustrated in Figure 7, it will be understood that other parameters, such as colour, or saturation or shade of a colour could be used instead or as well. For example, a colour transition from intensive pink to warm white could be defined (for example following a line or trace in colour space), with a parameter (which may be expressed as a percentage) representing a position along that particular colour transition. Such a colour based profile could be used together with a brightness profile to provide an overall lighting control pattern. The two profiles need not be the same, for example brightness could be set to transition to the background or default level over a longer distance than colour. Alternatively the colour and brightness could be combined providing a single lighting transition from a first setting point of brightness and colour, to another setting point of brightness sand colour.

Light pole 714 can be seen to be at the edge of the profile, and therefore the dimming level for this pole is substantially unchanged from the background level, of 40% dimming in this case. At the location of pole 716, it can be seen that the dimming level, according to the profile should be 60%>, and so pole 716 has its light intensity increased from 40% dimming (background level) to 60% dimming accordingly. At the location of pole 718, the appropriate level of 80%> is set.

It will be understood that the example of Figure 7 the light poles do not need to be physically located in a perfect line corresponding to a single section. Rather, Figure 7 represents one of a plurality of possible 2D cross sections through an area, and a profile may effectively be considered as a 3D surface, which can be mapped onto any light unit controllable as part of the lighting system falling within that surface, in the manner of the examples described with respect to Figure 7, to provide the desired distribution of illumination.

Figure 8a shows a first example of a method of controlling the lighting units to be modulated in response to an event. Light poles 810 each have a direct connection to network 804, which may be the same as network 104 of Figure 1 for example. In this way, each light pole can receive a control command or message from a backend or controller such as CMS 114 of Figure 1 for example. In this example each message is individually addressed and includes information specific to the addressed light unit.

Figure 8b shows an alternative control method, in which the backend or central controller communicates to a group of lighting units via a segment controller 830, such as controller 106b of Figure 1. Thus the backend sends one message, which contains control information for all targeted lighting units. Once received, the segment controller relays the information further with the relevant lighting units, either using a broadcast message (star network topology - not shown in Fig 8b) or to a first lighting unit of the group, which then forwards information to other lighting units sequentially via multi-hop message propagation as shown.

In Figure 8c, there is no separate central controller or backend. All control logic and message propagation is performed in a decentralised, distributed manner. In this particular example of distributed control, the lighting unit nearest to the relevant event acts as a computing node, and determines those lighting units to be controlled in response, and the relevant control parameters. It further propagates the messages to the relevant lighting units, either in a star network configuration (eg 850) or a multi-hop configuration (eg 840), or a combination.

Figure 9 shows an example of how graded transition can be provided over different distances.

A first profile 902 is substantially similar to profile 702 of Figure 7, and results in modulation or overriding of the background level, to give dimming levels as illustrated in the first line 940. A second profile 904 is also shown, which could correspond to a different type of event, or the same type of event at a different time or involving a different number of people for example. The second profile provides the same peak or target illumination at the location of the event, or the centre of the event, but provide a more gradual transition, over a greater distance (at least along the direction shown). This could be achieved by stepping the dimming factor down by 10% at each of lighting units 910, however in some cases this may not be possible or desirable, for example because the units do not have that a sufficiently fine level of illumination control, or the communication overhead is considered too great in a particular system. In such cases, an alternative mapping of the profile to the lighting units can be performed, resulting in every second lighting unit having a dimming level reduced by 20%, as shown in the second level 950.

Figure 10 shows an inverse or reverse gradient profile 1002, and corresponding light output or dimming levels. In this example, a background dimming level 1004 is 80%, but target lighting 1006 at an event is determined to be lower than the background level, say, 20%>. This might correspond to a case of police offices undertaking a covert operation, and wishing to move unnoticed. A linear profile is used to transition back (up) to the background level of 80%>, and light poles 1010 have dimming values set accordingly, with intermediate values of 40% and 60% with increasing distance from the event.

Figure 11 is a flow diagram illustrating an example lighting control method. At step Al 102, a trigger is received for example from a user or observer, or an automatic trigger from a sensor or combination of sensors. The trigger indicates an event, possibly classified into an event type, and the location of the event.

At step SI 104, an appropriate or desired profile is determined in response to the event. As discussed, the profile may depend on a number of factors, including

geographical, behavioural and/or ambient factors. At step SI 106, lighting units which fall within the extent of the determined profile are identified, and their positions obtained.

Typically the positions of each of the lighting units will be stored in the lighting system, and the relative positions of such units in relation to the detected event can be determined.

At step SI 108, the profile is mapped onto the lighting units identified at step SI 106. Not all lighting units identified need be affected, if it is determined that the desired lighting output can be met, or sufficiently approximated. For those units affected, light output parameters are obtained by the mapping. Lastly at step SI 110, the lighting units are controlled, using the output parameters obtained from the mapping, to provide the desired illumination pattern with the desired graded transition.

It will be understood that the present invention has been described above purely by way of example, and modification of detail can be made within the scope of the invention. Each feature disclosed in the description, and (where appropriate) the claims and drawings may be provided independently or in any appropriate combination.

The various illustrative logical blocks, functional blocks, modules and circuits described in connection with the present disclosure - including the CMS 114, and lighting controllers 106 - may be implemented or performed with a general purpose processor, a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field programmable gate array (FPGA) or other programmable logic device (PLD), discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the function or functions described herein, optionally in combination with instructions stored in a memory or storage medium. A described processor or controller may also be implemented as a one or a combination of computing devices, e.g., a combination of a DSP and a microprocessor, or a plurality of microprocessors for example. Conversely, separately described functional blocks or modules may be integrated into a single processor. The steps of a method or algorithm described in connection with the present disclosure may be embodied directly in hardware, in a software module executed by a processor, or in a combination of the two. A software module may reside in any form of storage medium that is known in the art. Some examples of storage media that may be used include random access memory (RAM), read only memory (ROM), flash memory, EPROM memory, EEPROM memory, registers, a hard disk, a removable disk, and a CD-ROM.

Other variations to the disclosed embodiments can be understood and effected by those skilled in the art in practicing the claimed invention, from a study of the drawings, the disclosure, and the appended claims. In the claims, the word "comprising" does not exclude other elements or steps, and the indefinite article "a" or "an" does not exclude a plurality. A single processor or other unit may fulfil the functions of several items recited in the claims. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage. A computer program may be stored and/or distributed on a suitable medium, such as an optical storage medium or a solid-state medium supplied together with or as part of other hardware, but may also be distributed in other forms, such as via the Internet or other wired or wireless telecommunication systems. Any reference signs in the claims should not be construed as limiting the scope.