GB2511751A

GB2511751A - Vehicle and method for responding to illumination on a vehicle

Info

Publication number: GB2511751A
Application number: GB1304318.7A
Authority: GB
Inventors: Roy Jones
Original assignee: Jaguar Land Rover Ltd
Current assignee: Jaguar Land Rover Ltd
Priority date: 2013-03-11
Filing date: 2013-03-11
Publication date: 2014-09-17
Anticipated expiration: 2033-03-11
Also published as: GB2511751B; WO2014139957A1; GB201304318D0

Abstract

A method for responding to illumination incident upon a vehicle 101, the method comprising: providing a vehicle, the vehicle comprising at least a first camera 104, 105, 108, 109 and at least one first system; recording a first image of a first location; determining the presence of a first shadow 103 cast by the vehicle in the first image; determining at least one dimension x, y of the first shadow; deriving at least one value for use with the first system, the value depending upon the dimension of the first shadow; and altering the behaviour of the first system according to the value for use with the first system. The system may comprise an automatic temperature control (ATC) system, such that the temperature or amount of air blown through vents in regions of the vehicle may be altered depending on where and how large the shadow is. The system may also comprise a tyre pressure monitoring system, or a display unit which is capable of being altered in brightness. The invention also comprises a vehicle using the method and a control unit for such a vehicle.

Description

Vehicle and Method for Responding to Illumination on a Vehicle

TECHNICAL FIELD

This invention relates to a method for responding to illumination on a vehicle, and to a vehicle capable of the same. Aspects of the invention relate to a method and to a vehicle.

BAG KG ROUND

The Climate Control systems in vehicles are becoming increasingly refined, and customers are demanding increased levels of cabin comfort, both for the front occupants and the rear passengers. In order to deliver this, vehicle manufacturers are producing vehicles with multi-zone Automatic Temperature Control (ATG) units. These ATC systems break the interior of a vehicle into a plurality of zones, and allow users to adjust the temperature setting for their zone independent of the setting in other zones. Two, three and four zone systems are now commonplace in premium vehicles.

The comfort of a user in a vehicle is often influenced by the sun. If a user is in direct, bright sunlight, then they will be warmer than another user who is in shadow. ATC systems therefore also attempt to account for the heating effects of solar loading on the vehicle occupants by adjusting the temperature, airflow and air distribution for a particular zone based on measurements of the solar intensity made using solar sensors.

Typically these solar sensors comprise one or more photodiodes, typically positioned throughout the vehicle in order to detect the light level at different points. However these sensors only provide a limited amount of information. A single sensor can only measure the solar load at one particular point in the vehicle (normally the sensor is located at the top of the vehicle dashboard). Dual zone sensors in this position improve things by allowing the solar load on each side of the vehicle to be measured, but are still unable to account for variations in load due to sun direction. For example, a sensor on the dashboard may be in full sunlight while the driver is still in shade, or the driver may be in full sunlight through a side window while the sensor remains in the shade.

Solar sensors mounted in the rear of the vehicle are even less effective at determining the solar loading on the rear occupants, as in most vehicle designs they must be placed even further from the users. A sensor mounted on a rear parcel shelf could be subjected to strong sunlight from above or behind, when the rear occupants are actually in the shade. Similarly under other conditions the sensor may be in relative shade when a rear occupant is being subjected to significant solar load through a side window or sunroof, particularly with the large panoramic sunroofs that are now becoming popular (see Figure 1 for an example).

As such, existing ATO systems are unable to adapt effectively to a changing direction of illumination. As such, an improved system or method for temperature control would be desirable.

SUMMARY OF THE INVENTION

In accordance with an aspect of the present invention there is provided a method for responding to illumination incident upon a vehicle, the method comprising: recording a first image of a first location; determining the presence of a first shadow cast by the vehicle in the first image; determining at least one dimension of the first shadow; deriving at least one value for use with a first system of the vehicle from the at least one dimension of the first shadow; and altering the behaviour of the first system according to the at least one value.

The method may comprise providing on the vehicle a camera system comprising at least a first camera for recording the first image.

The invention thus provides a method for determining the location of the sun relative to the vehicle by using the image detection algorithms of the camera system that detects the vehicle's own shadow, and using the detected image and calculated sun position to provide inputs to the first system.

An increasing number of vehicles are now being fitted with camera systems to provide driver assistance features such as reverse guidance. Premium vehicles utilise multi-camera systems with cameras mounted on both sides of the vehicle as well as at the front and the back. Using image processing techniques it is even possible to stitch together images from several cameras to produce a birds-eye view" of the vehicle and its surroundings.

Detecting the vehicle's own shadow has a number of advantages when compared to attempting to detect the shadows of other objects. In strong sunlight, when compensation for solar effects is most often required, the vehicle's shadow is always there, and grows stronger, and hence easier to recognise, as the brightness of the sunlight increases. The various shapes of the vehicle's shadow can be determined in advance, since the shape of the vehicle is known, and hence the image detection algorithm can locate them more easily.

The method may comprise determining the dimensions of a feature of the first shadow. The method may comprise determining the location of a feature of the first shadow. By using key features of the vehicle's shadow, such as the shadow created by the door mirrors, the system can be made to work even with camera systems that do not provide full coverage of the vehicle perimeter.

Typically, the illumination of the vehicle is primarily due to the sun. Typically the illumination is solar illumination. The illumination may be artificial illumination. For example, the illumination source may be a light bulb.

By measuring the dimensions of a shadow in a first location and responding to that, the invention can respond to illumination in a second location, which need not be directly monitored.

It may be that the first shadow falls on the vehicle. It may be that the first shadow falls within the vehicle. For example, the shadow may fall on a door of the vehicle, or on the dashboard.

Where the shadow falls upon the vehicle, this may be advantageous since the shadow is then falling upon a known shape.

It may be that the invention comprises: relating the at least one dimension of the first shadow to an expected illumination direction; and altering the behaviour of the first system according to the expected illumination direction. Alternatively, the actual illumination direction may not be calculated, and instead the at least one dimension of the first shadow may be related directly to an operating parameter of the vehicle.

Typically, the vehicle comprises at least one light intensity sensor, the method further comprising measuring the illumination load at a first point using the light intensity sensor. It may then be that the at least one value for use with the first system depends upon the illumination load at the first point.

It may be that the invention comprises: relating at least one dimension of the first shadow and the illumination load at the first point to an expected illumination load at a second point; and altering the behaviour of the first system according to the expected illumination load at the second point. It may be that the illumination load is a solar load. Typically, the illumination load is a measure of the flux of light over a given area at a given point.

Since the position of the sun relative to the vehicle can be determined using a method according to the invention, the actual positioning of a solar sensor becomes less critical than in the prior art. The light intensity sensor may be located on the roof of the vehicle, for example in a roof antenna pod. This can help to reduce the risk of the sensor falling into a localised shadow, and giving a misleading indication of illumination load.

In some embodiments, the vehicle comprises a second system, the method further comprising determining a status of the second system. It may be that the at least one value for use with the first system depends upon the status of the second system. The second system may be a suspension system, or another system which determines the vehicle's ride height. In this way, changes in the extent of the shadow cast by the vehicle and the distribution of shadows within the vehicle due to changes in the height of the vehicle above the ground can be compensated for.

A second aspect of the present invention provides a vehicle comprising at least a first camera, at least one first system and a control unit, the control unit being arranged to: cause the first camera to record a first image of a first location; determine the presence of a first shadow cast by the vehicle in the first image; determine at least one dimension of the first shadow; derive at least one value for use with the first system, the at least one value depending upon the at least one dimension of the first shadow; and alter the behaviour of the first system according to the at least one value for use with the first system.

Typically, the vehicle comprises at least one light intensity sensor, the control unit being arranged to measure the illumination load at a first point using the light intensity sensor. The at least one value for use with the first system may then depend upon the illumination load at the first point.

It may be that the vehicle comprises a second system, the control unit being arranged to determine a status of the second system. It may further be that the at least one value for use with the first system depends upon the status of the second system.

The light intensity sensor may be a photodiode. Alternatively, the light intensity sensor may be a camera or any other suitable sensor.

It may be that the vehicle comprises a database in which the at least one dimension of the first shadow is correlated to values for use with the first system, and wherein deriving at least one value for use with the first system comprises: accessing the database; and determining at least one value for use with the first system which is correlated with the at least one dimension of the first shadow. The database may also correlate the values for use with the first system with the status of a second system and illumination intensity. Instead of a database an equation, a set of equations, a computer model or any other suitable process could be used.

Typically, the at least one first system comprises an Automatic Temperature Control (ATO) system. It may be that alteiing the behaviour of the ATC system comprises altering the temperature of the air blown by a first air vent. Altering the behaviour of the ATC system may comprise altering the amount of air blown by a first air vent.

The values could be a target temperature, a distribution of air between different vents, blower speeds or any other variable used by the ATC system. The values could be absolute, such as a target temperature of 21 degrees Celsius. Alternatively, the values may be relative, such as an adjustment to the existing target teniperature. For example, the value may be a percentage of a preset blower speed or temperature, or a set adjustment such as a reduction in temperature of a certain number of degrees.

Altering the behaviour of the ATO system may comprise altering the amount and/or the temperature of the air blown by a plurality of vents. Altering the behaviour of the ATC system may comprise altering the distribution of air between a plurality of vents. For example, altering the behaviour of the ATC system may comprise directing more air towards a user's feet, or face, as required. In another example, altering the behaviour of the ATC system may comprise directing warmer air towards a user's feet, and directing colder air towards their face. This might be useful, for example, if the user's face is in direct sunlight while their feet are not.

It may be that the at least one first system comprises a Tyre Pressure Monitoring (TPM) System. The 1PM system can therefore be prevented from sound a false overpressure alarms due to solar heating.

It may be that the at least one first system comprises a light control system such as an automatic blind or a variable tint window.

It may be that the at least one first system comprises a display unit suitable for displaying an image, and altering the behaviour of the display unit comprises altering the brightness of the image displayed on the display unit. It may be that altering the behaviour of the display unit comprises altering the brightness of the image displayed on the display unit in a viewing direction dependent on the direction of illumination incident on the vehicle.

Within the scope of this application it is expressly intended that the various aspects, embodiments, examples and alternatives set out in the preceding paragraphs, in the claims and/or in the following description and drawings, and in particular the individual features thereof, may be taken independently or in any combination. For example, features described with reference to one embodiment are applicable to all embodiments, unless such features are incompatible.

BRIEF DESCRIPTION OF THE DRAWINGS

Exemplary embodiments of the invention are further described hereinafter with reference to the accompanying drawings, in which: Figures 1, 2 and 3 are illustrations of a first vehicle according to an embodiment to the invention; Figure 4 is a diagrammatic representation of some of the systems within the first vehicle; Figure 5 is a table showing a fragment of a database; and Figures 6 is a diagrammatic representation of some of the systems within a second vehicle.

DETAILED DESCRIPTION

Figures 1, 2 and 3 show a first vehicle 101. The first vehicle 101 is illuminated by the sun, which is above the vehicle in the direction of arrow 102. The vehicle therefore casts a shadow 103 on the ground around the first vehicle 101.

The first vehicle 101 comprises a plurality of cameras. A door mirror camera 104, 105 is located in each door mirror 106, 107 of the first vehicle 101. Each door mirror camera 104, provides a view of the ground to one side of the first vehicle 101. The first vehicle 101 also comprises a forward camera 108 and a rearward camera 109, which provide a view of the ground in front of and behind the first vehicle 101 respectively.

Lastly, the first vehicle 101 comprises a light sensor 110, which is located on the roof of the first vehicle 101 and directed upwards. The light sensor 110 is suitable for measuring the intensity of sunlight incident upon the first vehicle 101.

Figure 4 shows a diagrammatic representation of the arrangement of a plurality of related systems in the first vehicle 101. The cameras 104, 105, 108, 109 and the light sensor 110 all provide input to a control unit 120, which in turn provides inputs to an Automatic Temperature Control (ATC) system 121, a Tyre Pressure Management (TPM) system 122, a display system 123 and a light control system 124.

When the ignition of the first vehicle 101 is turned on, the control unit uses the cameras 104, 105, 108, 109 to capture images of the ground around the first vehicle. The control unit then analyses the images and attempts to identify shadow within the images. This is done by analysing areas of light and shade within the image. Once a shadow is identified, the shape of the shadow is used to determine if it has been cast by the first vehicle by comparing the observed shape with a range of expected shapes. Since the profile of most vehicles does not change significantly over time, the shapes of the shadows cast are highly recognisable.

In some vehicles the profile of the vehicle can change. Where this is the case, for example in a convertible vehicle, the control unit may be provided with an additional input which indicates the change in profile. So for a convertible vehicle the control unit would know whether the roof was up or down, and would search for a first shape when the roof was up and a second shape when the roof was down.

Once the camera system has detected the shadow 103 of the first vehicle 101, it is then possible to determine the location of the sun relative to the vehicle 101 from the position of the shadow 103 relative to the first vehicle 101. This is illustrated in figures 1, 2 and 3. The distance x is the distance from the side of the first vehicle 101 to the edge of the shadow 103, as indicated in figures 1 and 3. Since the shape of the first vehicle 101 is known, it is possible to calculate an angle ci from the value x, where ci is the angle of illumination of light from the sun as measured in a transverse plane of the vehicle. Similarly, the value y is the distance from the rear of the first vehicle 101 to the edge of the shadow 103, as indicated in figures 1 and 2. An angle w can be calculated from the value y, where w is the angle of illumination of the light from the sun as measured in the sagittal plane of the vehicle (i.e. a vertical plane which passes from the front to the rear of the vehicle dividing it substantially into right and left halves). In combination, the two angles a and w provide the information required to produce a vector from the vehicle directly to the sun's location in the sky as indicated by arrow 102.

Once the position of the sun relative to the vehicle has been established, and given the known geometry of the first vehicle 101 this information can be used to calculate whether any point in the first vehicle 101 is in direct light from the sun (through the windows and/or sun-roof of the vehicle), or in the shade (cast by non-light-transmitting parts of the vehicle).

For example, in the illustration shown in figure 1, a person sitting on the left hand side of the car (left hand side here being judged from the driver's point of view) would be exposed to sunlight through the side windows, while a person sitting on the right hand side would not.

In addition, the light sensor 110 collects solar intensity data and provides this to the control unit 120. By combining solar intensity data with data on the direction of illumination, an expected amount of solar loading being applied at any point in the vehicle can be calculated, again given the vehicle's known geometry. Therefore the solar loading being applied to each seating position within the vehicle can be calculated, and the air flow, temperature and distribution provided for that occupant can be adjusted as appropriate.

While an embodiment of the invention could undertake the calculations outlined above, in fact the control unit 120 of the embodiment presently described does not. Instead, the control unit 120 comprises a database of predetermined values which relate to certain operating parameters within the first vehicle 101. The predetermined values are related to the measurements x and y, as well as the solar intensity data. These operating parameters are calculated according to the known geometry of the first vehicle 101, and provided for every vehicle of that model, taking into account any variations in the vehicles such as sunroof fitment and glazing options including privacy glass, infrared reflective glass and so on.

The interior of the first vehicle 101 comprises four zones, each zone surrounding one of four seats. When configuring the ATC system 121, a user in the first vehicle 101 can select a target temperature for each zone, and also specify how much air is blown across each zone and how the air is distributed if they wish. Alternatively, the ATC system 121 can automatically select distributions and quantities of air based upon the desired temperature and the temperature measured by sensors located inside the first vehicle 101. The user can also set the ATC system 121 to compensate for solar load, in which case the control unit 101 measures x and y and collects solar intensity data as described above and consults the database to retrieve predetermined values which it then provides to the ATC system 121.

The predetermined values comprise adjustments which are applied to the target temperature, the amount of air blown, and the distribution of the air blown in each zone by the ATC system 121. The control unit 120 then continues to monitor the values of x and y and the solar intensity and, in the event of a change, the control unit 120 first consults the database to see if the predetermined values have also changed, and then notifies the ATC system 121 of any change in the predetermined values.

Figure 5 is a table showing a fragment of the database used by the control unit 120 in the first vehicle 101. The table relates values of x in centimetres, along the horizontal axis, and values of y in centimetres, along the vertical axis, to the rotational speed of a fan in a first zone of the first vehicle 101. The fan speed is given as a percentage in the body of the table.

In use, the ATC system 121 first determines a first fan speed based upon the settings chosen by the user. The first fan speed is then adjusted according to the percentage retrieved from the database to produce a second fan speed. So if the first fan speed is initially determined to be 10 rotations per second, and the percentage is 90%, then the second fan speed is 9 rotations per second.

As can be seen in Figure 5, the adjustment value falls as x and y increase. This is because an increase in x or y indicates that the sun has moved relative to the vehicle, directing less sunlight into the first zone and so requiring less air circulation to keep the occupant cool.

Alternatively, as the sun begins to strike the occupant more directly at x=-10, y=-10, the fan speed begins to increase in order to keep them cool.

The second fan speed is a target fan speed. If it is not possible for the fan to go fast enough to match the second fan speed, then the fan will simply go as fast as it can.

In an example, the first zone is in shadow at a time t1. The control unit 120 determines the solar load based upon x, y and the solar intensity data. Using this information, the ATC system 121 determines what temperature air to blow and where. At a later time t2, the vehicle turns a corner, causing the sun to shift relative to the first vehicle 101 and increasing the light level in the first zone. This causes both x and y to change, which is recorded by the cameras 104, 105, 108, 109. The control unit 120 measures this change and consults the database to retrieve new predetermined values, which are passed onto the ATC system 121.

The ATC system 121 applies the predetermined values by adjusting the ATC settings. In this instance, the ATC system 121 decreases the temperature of the air being blow and directs more air towards the occupant's face, in order to keep them feeling cool despite the direct sunlight.

At a still later time t3, the sun goes behind a cloud. This causes a drop in solar intensity, which is detected by the light sensor 110, which in turn transmits a signal to the control unit 120. The control unit 120 consults the database to retrieve new predetermined values, which are passed onto the ATC system 121. The ATC system 121 applies the predetermined values by adjusting the blower settings. In this instance, the ATC system 121 increases the temperature of the air being blown and directs more air towards the occupants feet, decreasing the amount directed towards their face, in order to keep them feeling warm despite the lack of direct sunlight.

The predetermined values returned by the database also depend upon the position of the seat in each zone of the vehicle, since the position of the seat may determine whether an occupant is in sunlight or in shade.

For similar reasons, the predetermined values returned by the database also depend upon the ride height of the first vehicle 101, since the height of the vehicle above the ground may change x, y and the distribution of shadow within the vehicle.

If a vehicle is parked side-on to the sun, then the tyres on the sunny side will be heated by the solar loading. This causes the temperature of the tyres and the air within them to rise, causing the pressure within the tyres to increase. The TPM system 122 therefore may flag a tyre pressure warning due to the pressure difference. To prevent this, the control unit also provides predetermined values to the TPM system 122. These predetermined values are calculated based upon an expected amount of heating in each tyre due to direct sunlight.

The TPM system 122 is configure to account for this solar heating when measuring the pressure in a tyre on the first vehicle 101, preventing false overpressure warnings without needing to measure the temperature of each tyre.

In bright sunlight, a display within the vehicle may be difficult to read, a condition sometimes referred to as display sunlight-washout. Therefore the database provides values relating to the brightness of displays within the first vehicle 101 to the display system 123. The display system 123 adjusts the brightness of the displays according to the values, making the screens brighter when illuminated by direct sunlight and dimmer when not. Dimming the screen in low light levels can help to avoid dazzling a driver or other occupants of the vehicle.

In vehicles equipped with multi-view displays the brightness of the displays may be altered independently in a plurality of viewing directions, for example by independently varying the brightness of a plurality of backlights. In such multi-view displays the predetermined values returned by the database also depend upon the position within the vehicle from which the occupant or occupants view the displays, since the position of the sun with respect to the vehicle and the viewing position there-within may determine whether or not an occupant experiences unwanted sunlight reflected from the display screen. The display system 123 adjusts the brightness of the displays according to the values, making the screens brighter in those directions within the vehicle in which incident sunlight is reflected, but maintaining normal brightness in those directions in which sunlight is not reflected.

The vehicle also comprises a number of light control systems. The light control systems, including sun visors and a blind which can be automatically deployed, and variable-tint windows which use, as an example, suspended particle devices to provide variable transparency. The database piovides values foi all of these systems, so that the first vehicle 101 can be configured, for example, to increase the tint and deploy blinds on a side of the car which is subject to a high solar load.

The view of the rear camera 109 may be obscured during the use of the first vehicle 101. For example, if the first vehicle 101 is towing a trailer, this would hide the extent of the shadow 103 behind the vehicle. For this reason, the control unit 120 can also use the door mirrors to measure the position of the tip of a shadow cast by a door mirror upon the ground. This is illustrated in Figure 1, in which the right door mirror camera 104 can be used to measure x' and y'. The measurements x' and y' also relate to the position of the sun in the sky, and the database further provides values relating to x' and y'.

In some circumstances, some feature of the terrain may make it difficult to identify shadows cast upon the ground. This can occur because of the colour of the terrain, or because of the shape of the terrain, for example if the terrain is ridged or otherwise roughened this can obscure the edge of shadows. For this reason, the control unit 120 can also measure the position of the tip of the shadow cast by a door mirror upon the vehicle itself. In Figure 1, for example, the control unit 120 can use the left door mirror camera 105 to record an image of the left door of the vehicle, and measure the position of a shadow cast by the loft door mirror 107 upon the door. This measurement also relates to the position of the sun in the sky, and the database further provides values relating to this measurement.

Each of the measurement techniques can be used alone or in combination. On other models of vehicle, a control unit could be configured to measure the location of shadows cast by other prominent features such as spoilers.

Figure 6 is a diagrammatic representation of systems in a second vehicle 201 according to the invention. The second vehicle 201 is similar to the first vehicle 101 described above, and similar systems are identified using the same numerals. The second vehicle 201 does not comprise the same database as the first vehicle 101, and is provided with additional systems. The second control unit 220 of the second vehicle 201 is configured to perform calculations based upon the known shape of the vehicle and the measured values of x and y to derive a and w, and the database in the second vehicle relates a and w to predetermined values which are used to control an ATC system 121, a 1PM system 122, a display system 123 and light control systems 124 as described above. The second vehicle further comprises a parking assistance system 211 and an emergency braking system 212, which between them comprise a plurality of sensors suitable for mapping objects located around the second vehicle in three dimensions. The sensors in the parking assistance system 211 and the emergency braking system 212 comprise active sensors such as sonar and radar based technology, and passive sensors such as stereoscopic camera systems. The second control unit 220 is configured to use these sensors to map the terrain around the car, and to take the shape of the terrain into account when calculating a and w. In this way the second control unit 220 can take account of curves and other distortions in the surrounding terrain which may distort a shadow cast by the second vehicle.

Embodiments described above mention solar illumination. However the invention is not restricted to solar illumination, and can work with illumination from other sources such as artificial illumination or lunar illumination. In particular, an embodiment according to the invention takes account of artificial illumination in order to control the brightness of a display within the vehicle when the vehicle is inside, or at night. For example if the vehicle is travelling between bright streetlights at night, the brightness of the display will be automatically adjusted according to the method described above in order to avoid dazzling the driver.

Throughout the description and claims of this specification, the words "comprise" and "contain" and variations of them mean "including but not limited to", and they are not intended to (and do not) exclude other moieties, additives, components, integers or steps.

Throughout the description and claims of this specification, the singular encompasses the plural unless the context otherwise requires. In particular, where the indefinite article is used, the specification is to be understood as contemplating plurality as well as singularity, unless the context requires otherwise.

Features, integers, characteristics, compounds, chemical moieties or groups described in conjunction with a particular aspect, embodiment or example of the invention are to be understood to be applicable to any other aspect, embodiment or example described herein unless incompatible therewith. All of the features disclosed in this specification (including any accompanying claims, abstract and drawings), and/or all of the steps of any method or process so disclosed, may be combined in any combination, except combinations where at least some of such features and/or steps are mutually exclusive. The invention is not restricted to the details of any foregoing embodiments. The invention extends to any novel one, or any novel combination, of the features disclosed in this specification (including any accompanying claims, abstract and drawings), or to any novel one, or any novel combination, of the steps of any method or process so disclosed.

Claims

CLAIMS1. A method for responding to illumination incident upon a vehicle, the method comprising: providing a vehicle comprising at least a camera system and at least one first system; recording with a first camera of the camera system a first image of a first location; determining using an image detection algorithm of the camera system the presence of a first shadow cast by the vehicle in the first image; determining at least one dimension of the first shadow; deriving at least one value for use with the first system from the at least one dimension of the first shadow; and altering the behaviour of the first system according to the at least one value.
2. A method as claimed in claim 1, wherein the vehicle comprises at least one light intensity sensor, the method further comprising measuring the illumination load at a first point using the light intensity sensor, and wherein the at least one value for use with the first system depends upon the illumination load at the first point.
3. A method as claimed in claim 2, wherein the light intensity sensor is a photodiode.
4. A method as claimed in any preceding claim, wherein the vehicle comprises a second system, the method further comprising determining a status of the second system, and wherein the at least one value for use with the first system depends upon the status of the second system.
5. A vehicle comprising a camera system, at least one first system and a control unit, the control unit being arranged to: cause a first camera of the camera system to record a first image of a first location; determine using an image detection algorithm the presence of a first shadow cast by the vehicle in the first image; determine at least one dimension of the first shadow; derive at least one value for use with the first system from the at least one dimension of the first shadow; and alter the behaviour of the first system according to the at least one value.
6. A vehicle as claimed in claim 5, wherein the vehicle comprises at least one light intensity sensor, the control unit being arranged to measure the illumination load at a first point using the light intensity sensor, and wherein the at least one value for use with the first system depends upon the illumination load at the first point.
7. A vehicle as claimed in claim 6, wherein the light intensity sensor is a photodiode.
8. A vehicle as claimed in claim 6 or claim 7, wherein the vehicle comprises a second system, the control unit being arranged to determine a status of the second system and wherein the at least one value for use with the first system depends upon the status of the second system.
9. A method or vehicle as claimed in any preceding claim, wherein the vehicle comprises a database in which the at least one dimension of the first shadow is correlated to values for use with the first system, and wherein deriving at least one value for use with the first system comprises: accessing the database; and determining at least one value for use with the first system which is correlated with the at least one dimension of the first shadow.
10. A method or vehicle as claimed in any preceding claim, wherein the at least one first system comprises an Automatic Temperature Control (ATC) system.
11. A method or vehicle as claimed in claim 10, wherein altering the behaviour of the ATC system comprises altering the temperature of the air blown by a first air vent.
12. A method or vehicle as claimed in claim 10 or claim 11, wherein altering the behaviour of the ATC system comprises altering the amount of air blown by a first air vent
13. A method or vehicle as claimed in any preceding claim, wherein the at least one first system comprises a Tyre Pressure Monitoring (1PM) System.
14. A method as claimed in any preceding claim, wherein the at least one first system comprises a display unit suitable for displaying an image, and altering the behaviour of the display unit comprises altering the brightness of the image displayed on the display unit.
15. A control unit for a vehicle comprising a camera system and at least one first system, the control unit being configured to: cause a first camera of the camera system to record a first image of a first location; determine using an image detection algorithm the presence of a first shadow cast by the vehicle in the first image; determine at least one dimension of the first shadow; derive at least one value for use with the first system from the at least one dimension of the first shadow; and alter the behaviour of the first system according to the at least one value.
16. A system, a method or a vehicle substantially as hereinbefore described with reference to the accompanying drawings.