WO2019091920A1

WO2019091920A1 - Method for displaying an image of the area surrounding a vehicle on a touch screen installed in the vehicle

Info

Publication number: WO2019091920A1
Application number: PCT/EP2018/080190
Authority: WO
Inventors: Stephanie AMBROISE
Original assignee: Renault S.A.S
Priority date: 2017-11-08
Filing date: 2018-11-05
Publication date: 2019-05-16
Also published as: FR3073310A1; EP3707679A1; FR3073310B1

Abstract

The invention relates to a method for displaying an image of the area surrounding a vehicle on a touch screen installed in the vehicle, comprising the steps of: a) displaying, on the touch screen, an image of the vehicle as it would be seen from a virtual camera placed in an initial position, and at least one graphic element associated with a position parameter of the virtual camera; b) acquiring the location of a point of the element selected by the user by pressing the touch screen; c) calculating the value of the position parameter according to the location of the point, and deriving a new position for the virtual camera; d) acquiring real images of the surrounding area using image sensors; e) using the real images to build a virtual image of the area surrounding the vehicle as seen from the virtual camera placed in the new position; and f) displaying the virtual image on the touch screen.

Description

METHOD FOR DISPLAYING AN IMAGE OF THE ENVIRONMENT OF A VEHICLE ON A TOUCH SCREEN EQUIPPING THE VEHICLE

TECHNICAL FIELD TO WHICH THE INVENTION RELATES The present invention relates generally to the field of driving aids for motor vehicles.

It relates in particular to a method of displaying an image of the environment of a vehicle on a touch screen fitted to the vehicle.

It also relates to a help system comprising:

four image sensors, each of the four image sensors being placed on one of the four sides of the vehicle, each of the four image sensors being able to acquire a real image of the environment of the vehicle,

- a touch screen, and

a computing unit adapted to implement a display method as mentioned above.

BACKGROUND

It is known to compose an image of a motor vehicle traveling in an environment from images captured by several cameras located on the four sides of the vehicle. This composite image is displayed to the driver on a display screen of the motor vehicle to enable him to detect obstacles located in the blind spots of the motor vehicle.

For the driver, this composite image seems to be acquired from a single virtual camera filming the motor vehicle from a given location located remote from the vehicle.

When the screen is tactile, the location of this virtual camera can generally be chosen by the driver by displaying a representation of the motor vehicle and a representation of the virtual camera and inviting the driver to move the virtual camera around the vehicle by swiping the touch screen with his fingers.

The help device then composes the image of the vehicle environment from the selected location of the virtual camera.

However, the driver may need to change the location of the virtual camera while he is performing a maneuver. However, the selection of the location of the virtual camera using this device is not practical, and may require too much attention from the driver, which impacts his safety.

OBJECT OF THE INVENTION

In order to remedy the aforementioned drawback of the state of the art, the present invention proposes a method of displaying an image of the environment of a vehicle on a touch screen fitted to the vehicle, comprising steps of:

a) display on said touch screen:

an image of the vehicle as seen from a virtual camera placed in an initial posture, and

at least one graphic element associated with a posture parameter of the virtual camera,

b) acquiring the position of a point of said selected element by pressing a user on the touch screen,

c) calculating the value of said posture parameter as a function of the position of said point, and deducing a new posture of the virtual camera, d) real image acquisition of the environment by a plurality of image sensors,

e) composition, from the real images acquired in step d), of a virtual image of the vehicle environment as seen from the virtual camera placed in the new posture determined in step c) , and

f) Display on the touch screen of the virtual image.

Thus, the invention provides a method for the user to easily choose a new posture of the virtual camera. The choice is indeed simplified by the display of the graphic element to show the user which postures can be adopted by the virtual camera. The user then selects the new posture of the virtual camera by exerting a simple press on the graphic element the touch screen. The selection of a new posture does not require much attention on the part of the user who can then focus on the road maneuvers he is performing.

Other nonlimiting and advantageous features of the display method according to the invention, taken individually or in any technically possible combination, are as follows:

a step is provided for constituting a representation of the vehicle as seen from the virtual camera in the new posture determined in step c), and in which, in step e), the virtual image is obtained by superimposing the representation of the vehicle on the environment,

the graphic element comprises a circle situated around the vehicle image and said posture parameter is an orientation angle of the virtual camera around the vehicle,

the graphic element makes it possible to select the angle of orientation of the virtual camera around the vehicle with a step of 1 degree,

the graphic element comprises a segment situated vertically with respect to the image of the vehicle and said posture parameter is a vertical distance between the vehicle and the virtual camera,

the graphic element comprises a segment situated horizontally with respect to the image of the vehicle and the posture parameter is a horizontal distance between the vehicle and the virtual camera,

- Steps c) to f) are repeated after each point support exerted by the user on the touch screen,

the virtual camera has an optical axis, in step c), the new posture of the virtual camera is defined so that said optical axis passes through a predetermined point of the vehicle, the invention also proposes a help system; driving a vehicle as defined in the introduction of which the computing unit is programmed to implement a method as defined above.

DETAILED DESCRIPTION OF AN EXEMPLARY EMBODIMENT The following description with reference to the accompanying drawings, given by way of non-limiting examples, will make it clear what the invention consists of and how it can be implemented.

In the accompanying drawings:

FIG. 1 is a diagrammatic section of a vehicle equipped with a driving assistance system according to the invention,

FIG. 2a illustrates a virtual camera of the vehicle of FIG. 1; FIG. 2b illustrates a virtual image of the vehicle of FIG. 1 as seen by the virtual camera;

FIG. 3a illustrates parameters of the virtual camera,

FIG. 3b is a schematic view from above of the vehicle of FIG. 1 and of the virtual camera, on which are represented coordinates of the virtual camera,

FIG. 3c is a schematic side view of the vehicle of FIG. 1 and of the virtual camera, on which are represented other coordinates of the virtual camera,

FIG. 4a is a schematic perspective view of the vehicle of FIG. 1, on which is represented a first graphic element associated with a first posture parameter of the virtual camera,

FIG. 4b is a schematic perspective view of the vehicle of FIG. 1, on which is represented a second graphic element associated with a second posture parameter of the virtual camera,

FIG. 4c is a schematic perspective view of the vehicle of FIG. 1, on which is represented a third graphic element associated with a third posture parameter of the virtual camera,

FIG. 5 represents a diagram illustrating the implementation steps of a display method according to the invention, and

FIG. 6 represents a perspective virtual image obtained according to the display method illustrated in FIG. 5.

FIG. 1 diagrammatically shows an automobile vehicle 1 equipped with a driving assistance system 3.

As will be well described in the remainder of this disclosure, this driver assistance system 3 comprises image sensors 5, a touch screen 7 and a calculation unit 9.

As shown in FIG. 1, the image sensors 5 are able to acquire a plurality of real images of an environment outside the vehicle 1.

Preferably, the driver assistance system 3 comprises four image sensors 5. Each of the image sensors 5 is placed on one of the four sides of the vehicle 1 (only two of the sensors 5 are visible in FIG. ).

A first image sensor (not shown) is placed at the front of the vehicle 1, for example below the vehicle logo 1. The first image sensor captures an area located at the front of the vehicle 1.

A second image sensor (not shown) is placed at the rear of the vehicle, for example above the license plate. The second image sensor captures an area at the rear of the vehicle 1.

A third image sensor 5 is placed on a first lateral side, for example the right side of the vehicle, for example under the right mirror. The third image sensor captures a first zone located laterally with respect to the vehicle 1, here to the right of the vehicle 1.

A fourth image sensor 5 is placed on a second lateral side, for example the left side of the vehicle, for example under the left rearview mirror. The fourth image sensor 5 captures a second zone situated laterally with respect to the vehicle 1, here to the left of the vehicle 1.

These image sensors 5 are here cameras. These cameras can be analog or digital. Here, digital cameras are preferably used because they make it possible to capture images of higher resolution than analog cameras, which subsequently makes it possible to obtain better results by applying the method of the invention.

The cameras have a large opening angle, for example close to or greater than 180 °. These cameras are equipped with lenses known as "fish-eye" in English.

A ^'this stage can be defined with reference to figure 3b a vehicle reference frame (0, Xv, Yv, Zv) attached to the vehicle 1. Here, the marker is considered an orthonormal coordinate system whose origin O is at the center of front side of the vehicle 1, the longitudinal axis (OXv) of which is oriented toward the rear of the vehicle 1, the transverse axis (OYv) of which is oriented towards the right of the vehicle and whose vertical axis (OZv) is oriented to the top.

It is also possible to define the center C of the vehicle 1 as the point situated halfway between the vehicle 1 in the longitudinal direction, in the transverse direction and in the vertical direction of the vehicle 1.

The calculation unit 9 of the vehicle 1 is able to receive the actual images acquired by the image sensors 5. It is furthermore programmed to compose a virtual image 13 of the environment of the vehicle 1 from the actual images acquired by the image sensors 5. Such a virtual image 13 is illustrated in FIG. 2b.

More specifically, the computing unit 9 is programmed to compose a virtual image 13 of the environment of the vehicle 1 as seen by a virtual camera 1 1 located at a distance from the vehicle 1. The virtual camera 11 is visible for example on Figure 2a.

In FIG. 2a, the virtual camera 1 1 is located above the vehicle 1. It will be noted that the virtual camera 11 does not exist in the real world: it is only a concept making it easier to understand the invention, which consists in composing a virtual image 13 corresponding to an image real as it would be captured by an actual camera if this actual camera was placed in the position of the virtual camera 11.

FIG. 2b illustrates the virtual image 13 as seen by the virtual camera 11. The virtual image 13 comprises a representation 15 of the vehicle 1, viewed from above, as well as the reconstituted environment 17 of the vehicle 1 seen under the same angle.

We define with respect to the virtual camera 1 1 an optical axis A ₀ . The optical axis Ao of the virtual camera 11 is chosen to pass through a fixed point of the vehicle 1, regardless of the position of the virtual camera 11. The fixed point is for example the center C of the vehicle 1.

Figure 3a shows some parameters of the virtual camera 11. The virtual camera 11 thus has a focal length f and a focal plane PF. The focal plane PF has a width Cx and a height Cy. The virtual camera further has a horizontal resolution Resh and a vertical resolution Resv.

As shown in Figure 3b, the virtual camera 1 1 has a posture, that is to say a position and an orientation, which is marked by coordinates

expressed in the vehicle reference (0, Xv, Yv, Zv). Coordinates

of the virtual camera 1 1 comprise a first coordinate X _Cam defined along the axis (OXv), a second coordinate Ycam defined along the axis (OYv), and a third coordinate -icam defined along the axis (OZv).

A fourth coordinate G is represented by Figure 3b. The fourth coordinate θ corresponds to an orientation angle Θ between the longitudinal axis (OXv) and the projected optical axis A ₀ in the plane

A fifth coordinate φ is represented by FIG. 3c. The fifth coordinate φ corresponds to an angle of inclination φ formed by the projected optical axis A ₀ in the plane

and the axis

The calculation unit 9 is able to calculate the coordinates

θ, φ) according to a command from the user, which command is formulated by pressing a user's finger on the touch screen 7.

Among these five coordinates, three of them are called "posture parameters" in the sense that they allow the user to vary the position and orientation of the virtual camera 1 1. The user can therefore three degrees of freedom of the virtual camera 11. The other degrees of freedom will not be directly modifiable by the user, which will include ensuring that the virtual camera 11 is always directed to the vehicle 1.

A first, a second and a third posture parameter can be defined here, which the user can easily vary by pressing "graphic elements" displayed on the touch screen 7 in order to modify the posture of the virtual camera 1 1 in relation to the vehicle 1.

The first posture parameter is the orientation angle Θ of the virtual camera 11.

A first graphical element 19, shown in FIG. 4a, is associated with this first posture parameter. This first graphic element 19 comprises a first circle C1 of radius R1 centered on the center C. The first circle C1 is located in the plane (XvYv). By pressing this first graphic element 19, the user will be able to vary the orientation angle Θ. We can therefore consider that the first graphical element 19 represents the values that can take the orientation angle Θ. The value of the orientation angle Θ is between 0 and 360 ° and can be varied in steps of 1 °.

The value of the first radius R1 is determined so that the first circle C1 encircles the representation 15 of the vehicle 1. The first radius R1 is for example equal to 2.5 m.

The first graphic element 19 is stored in a memory unit, from which it can be retrieved by the computing unit 9 which is able to transmit it to the touch screen 7.

The second posture parameter is the third coordinate Zcam which is reminded that it represents a vertical distance between the vehicle 1 and the virtual camera 11.

This third Zcam coordinate has a range of values that is preset and is stored in the memory unit. The value range is for example a function of the resolution offered by the image sensors 5 and by the screen Touch 7. Indeed, if the virtual camera 11 is placed too high, the objects present on the virtual image 13 will be too small to be recognizable or even visible by the user. Such a virtual image 13 could therefore not help the driver to maneuver the vehicle 1.

The third coordinate Zcam is for example between 1, 7 m and 3 m and can vary in steps of 5 cm.

It will be noted here that the third coordinate Zcam is associated with the angle of inclination φ of the virtual camera 1 1, since the optical axis A ₀ is defined as passing through the center C of the vehicle 1.

A second graphic element 21, illustrated by FIG. 4b, is associated with this second posture parameter. This second graphic element 21 is here formed by a vertical segment. By pressing this second graphical element 21, the user will be able to vary the third coordinate Zcam and the angle of inclination φ of the virtual camera 11. The second graphical element 21 is stored in the memory unit, since which it can be recovered by the computing unit 9 which is able to transmit it to the touch screen 7.

As shown in FIG. 4c, the third posture parameter is the second radius R2 of the second circle C2 on which the virtual camera 1 1 is located. The second radius R2 represents a horizontal distance between the virtual camera 11 and the vehicle 1.

For the reasons explained above, the second radius R2 is within a predefined range of values and stored in the memory unit. The second radius R2 is for example between 3.5 m and 6 m, it can be varied in steps of 5 cm.

A third graphic element 23 is associated with this third posture parameter. This third graphic element 23 is here formed by a horizontal segment. By pressing this third graphic element 23, the user will be able to vary the second radius R2. The third graphic element 23 is stored in the memory unit, from which it can be recovered by the computing unit 9 which is able to transmit it to the touch screen 7.

The first, second and third posture parameters 19, 21, 23 allow the calculation unit 9 to calculate coordinates (Xcam, Ycam, Zcam, Θ, φ) of the virtual camera 11 in the vehicle coordinate system (0, Xv , Yv, Zv). The virtual camera 11 is able to be moved by the user around the representation of the vehicle 1, which causes a change in his

Coordinates (Xcam, Ycam, Zcam, Θ, (p).

In addition to the image of the reconstituted environment 17, the computing unit 9 is able to recover or generate a representation of the vehicle 1 as seen by the virtual camera 11.

For this, a three-dimensional model of the vehicle could be stored in a memory unit of the driver assistance system 3.

But preferably, a plurality of representations of the vehicle 1 is stored in a memory unit of the driver assistance system 3.

The plurality of representations 15 is for example made from a simulation tool of the vehicle 1. For example 360 images are captured in perspective around the vehicle 1, in steps of 1 degree and remaining at a first value of the second radius R2 . Then, this operation is repeated by moving to a second value of the second radius R2. The second radius R2 is for example varied in millimeters.

In the same way, images of the vehicle 1 are captured by varying the third coordinate Zcam, and thus the angle of inclination φ of the virtual camera 11. Each captured image is named with its orientation angle value Θ , its second radius value R2 and its angle of inclination φ value, so the calculation unit 9 can easily retrieve the appropriate representation 15 for each posture of the virtual camera January 1.

The calculation unit 9 is furthermore capable of superimposing the appropriate representation of the vehicle 1 on the reconstituted image of the environment 17 to form the virtual image 13 as seen by the virtual camera 11.

The calculation unit 9 is also able to transmit the virtual image 13 to the touch screen 7.

The touch screen 7 is placed in the passenger compartment of the vehicle 1, for example on the dashboard of the latter.

The touch screen 7 is able to display the virtual image 13 as well as the graphic elements 19, 21, 23 transmitted by the calculation unit 9.

Preferably, the touch screen 7 is able to display images in colour.

The touch screen 7 is furthermore able to acquire the position of a selected point P by the occasional support of a user on said touch screen 7.

As shown in FIG. 1, a screen mark (0e, Ye, Ze) is associated with the touch screen 7. The origin 0e of the screen mark (Oe, Ye, Ze) is for example located on a corner of the touch screen 7, for example the lower left corner. The axis (OeYe) extends along a horizontal axis of the touch screen 7. The axis (OeZe) extends along a vertical axis of the touch screen 7.

The point P on which the user pressed has two-dimensional coordinates (yp, ZP). These two-dimensional coordinates (yp, ZP) are expressed in pixels.

The touch screen 7 is able to determine the two-dimensional coordinates (yp, ZP) of the selected point P (for example by means of a computer associated with the touch screen 7) and to transmit them to the calculation unit 9. The operation a touch screen 7 is well known to those skilled in the art and will not be described in detail.

Referring now to FIG. 5, a method for displaying an image of the environment of a vehicle 1 on a touch screen 7 fitted to the vehicle 1 can be described in greater detail.

This display method comprises a step a) of display on the touch screen 7 of one of the representations of the vehicle 1 and of at least one graphic element 19, 21, 23 among the first, second and third graphic elements 19, 21, 23 previously described.

At the beginning of the mission, the vehicle 1 can be represented as seen from an initial position PosO of coordinates (Xcamo, Ycamo, Zcamo, θο, φο) predefined of the initial virtual camera 1 1 in the vehicle reference (0, Xv, Yv , Zv).

The touch screen 7 displays for example the first graphic element 19 associated with the first posture parameter (the orientation angle Θ).

By simultaneously displaying the representation 15 of the vehicle 1 and the first graphical element 19, the choice by the user of the posture of the virtual camera 1 1, and therefore the virtual view of the environment, is facilitated. Indeed, the user quickly understands at which locations he can place the virtual camera 1 1. The choice of the location of the virtual camera 1 1 does not require great attention since a single point support with the finger is enough, and user can focus on the maneuvers he is doing.

The touch screen 7 may further display instructions to the user. These instructions can explain to him how to select the location of the virtual camera 11. According to the invention, the selection is made by a one-off support of the user on the touch screen 7, more precisely on one of the graphical elements displayed. .

During a step b), the touch screen 7 acquires the position of a first point P1 of the first graphic element 19 selected by a user press exerted on the touch screen 7. The position of the first selected point P1 is expressed by a set of coordinates in pixels in the screen frame (0,

Ye, Ze) previously described.

The coordinates of the first selected point P1 are

transmitted to the computing unit 9.

During a calculation step c), the calculation unit 9 calculates the value of the first posture parameter, here the orientation angle θι of the virtual camera 11 around the vehicle 1, as a function of the coordinates (yp). i, ZPI) of the first selected point P1 in order to deduce a new posture Pos1 of the virtual camera 1 1.

Calculations and transformations used by the calculation unit 9 are now described in order to obtain the value of the orientation angle θι, which makes it possible to deduce the first coordinates of the virtual camera 11.

The orientation angle θι is determined by means of the formula:

At this stage, it is recalled that (Xc, Yc, Zc) are the coordinates of the center C of the vehicle 1 defined in the vehicle mark and that R1 is the radius of the first circle C1 (first graphical element 19). The coordinates (Xc, Yc, Zc), the value of R1 as well as other variables used in the calculations which will be described later, such as

and R2, are stored in the memory unit.

In addition, the coordinates (XVPI, yvpi, ZVPI) are defined as the three-dimensional coordinates of the first selected point P1 in the vehicle frame (0, Xv, Yv, Zv). The only unknown variable of the equation of the angle of orientation θι is therefore the coordinate XVP-I. The coordinate is determined by the formula:

In this formula Xcamo and Ycamo are the initial coordinates, and therefore known, of the camera in the vehicle reference. Zc is also known.

R3 is determined using the formula:

Where Zcamo and Xcamo are known.

The coordinates (xpn, ypn,) are the coordinates of the first selected point P1 projected onto a first focal plane PF1 of the virtual camera 1 1, and expressed in the vehicle coordinate system (0, Xv, Yv, Zv) (the first focal plane PF1 being associated with the first posture of the virtual camera 1 1).

To calculate the coordinates xp ₁₁ and using projections projections equations:

Where we remember that yp ₁ and zpi are the coordinates of the first selected point P1 and therefore known.

With general:

Perspective projection equations associated with Ry matrices and

Rz so allow to calculate

and. The knowledge of xpn and z

can calculate

and

and thus to go back to and finally to the orientation angle θ1.

Once the calculation unit 9 has determined the value of the first orientation angle θ1, it can use it to calculate the other coordinates

of the first posture of the virtual camera 11

The coordinates of the first posture of the

virtual camera 11 are given by:

Indeed, here Yc is zero because the center C of the second circle C2 is located on the axis (OYv). Moreover, since the first graphic element 19 does not make it possible to modify the height of the virtual camera 11, the first values of the coordinates Zcam and φ remain unchanged.

In a step d), the image sensors 5 acquire real images of the environment of the vehicle 1. The step d) can take place simultaneously with the preceding steps a), b), c), or before those -this.

The actual images are transmitted to the computing unit 9 which composes a virtual image of the environment of the vehicle 1 as seen from the virtual camera 1 1 during a step e).

The calculation unit 9 selects the real images to be used according to the posture of the virtual camera 1 1. For example, when the virtual camera is placed above the vehicle 1 with an optical axis parallel to the axis (OZv) vehicle mark

the virtual image 13 displayed is that represented by FIG.

For another posture of the virtual camera 11, the computing unit 9 can for example compose the virtual image 13 from the real images of only one, two or three image sensors 5.

This step of composing the image does not form the heart of the invention and is already well known to those skilled in the art, it will not be described in more detail here.

The display method further provides a step of reading a representation of the vehicle 1 as seen from the new posture Pos 1 of the virtual camera 11 deduced in step c). The representation 15 of the vehicle 1 is for example selected from the plurality of representations 15 stored in the memory unit.

Then, the virtual image 13 of the environment 17 and the representation 15 of the vehicle 1 are displayed on the touch screen 7 during a step f). Thus, the user can easily choose the location of the virtual camera 11, and accesses easily understandable information enabling him to better visualize the environment 17 of the vehicle 1.

It can then be provided that the calculation unit 9 then controls the display of the second graphic element 21 in order to allow the user to adjust the height of the virtual camera 11, before displaying the third graphic element 23 in order to adjust the horizontal distance between the virtual camera 11 and the vehicle 1.

More specifically, to acquire the second posture parameter, the calculation unit 9 displays the second graphic element 21 associated with the second posture parameter, that is to say the vertical segment during step a).

The vertical segment is for example displayed along a vertical axis passing through the center C.

Then, during step b), the computing unit 9 acquires the position of a second selected point P2 by pressing on the touch screen at the vertical segment.

This second selected point P2 makes it possible to calculate, during step c), on the one hand, a second value of the coordinate Zc _a m 2 of the second posture Pos 2 of the virtual camera 1 1 and, on the other hand, a second value of its angle inclination 92.

The coordinates of the second selected point P2

in the vehicle mark

So we try to get the altitude For this, we use the formula

following mathematical:

In which :

Coordinates

are the coordinates of the second selected point P2 projected on a second focal plane PF2 of the virtual camera 11, and expressed in the vehicle coordinate system (the second focal plane

PF2 being associated with the second posture of the virtual camera 11).

To calculate the coordinates we use equations of

outlook projections:

Where it is recalled that yp2 and ZP2 are the coordinates of the second selected point P2 and therefore known. Moreover, in the matrix Ry, the orientation angle Θ around the vehicle 11 has the first value Θ1 previously calculated. By placing itself in the second focal plane PF2, the Thales theorem is applied as follows:

The virtual camera 11 is therefore positioned in

In addition, since the virtual camera 1 1 is oriented towards the center C, the angle of inclination φ is:

Steps d) and e) are then repeated so as to display an image of the environment 17 and a representation of the vehicle 1, seen from an altitude corresponding to the wish of the user.

Finally, the calculation unit 9 controls the display of the third graphic element 23 on the touch screen 7 during a new step a).

The horizontal segment of the third graphic element 23 is for example arranged along an axis passing through the center C and at an angle equal to the orientation angle θ + π / 2 with respect to the longitudinal axis (OXv) .

In step b), the computing unit 9 acquires the position of the third selected point P3 by pressing the horizontal segment. Coordinates

of the third selected point P3 on the touch screen 7 are transmitted to the calculation unit 9.

This third selected point P3 makes it possible to calculate, during step c), a new horizontal distance

2f to be applied between the vehicle 1 and the virtual camera 1 1.

To perform these calculations, the calculation unit 9 uses the values of orientation angle θ ₁ , and angle of inclination

previously calculated.

The coordinates of the projected third point selected P3 in the vehicle reference (Xv, Yv, Zv) are noted

with R2i the initial value of the radius R2.

We have :

with R1 the initial value of the first radius R1 and R1f the final value of the first radius R1. We have noted the mathematical formula:

In which X _vp is the coordinate of the point of intersection of the circle of radius R1 and the horizontal segment of the third graphic element 23. The coordinate x _vp is obtained with the formula:

Where all the variables are known. The coordinate

is calculated using the formula:

Where Xcamo and Ycamo are the initial coordinates of the virtual camera 1 1 in the vehicle mark. Zc is also known.

R3 is determined using the formula:

Or :

The coordinates are the coordinates of the third

selected point P3 projected on a third focal plane PF3 of the virtual camera 11, and expressed in the vehicle reference (0, Xv, Yv, Zv) (the third focal plane PF3 being associated with the third posture of the virtual camera 11).

By placing itself in the third focal plane PF3, the Thales theorem is applied as follows:

Or :

To calculate the coordinates and we use equations of

outlook projections:

Where we remember that and are the coordinates of the third point

selected P3 and therefore known. Moreover, in the matrix Ry, the orientation angle Θ around the vehicle 11 has the first value θ _ι previously calculated, and in the matrix Rz, the inclination angle φ has the value 92 previously calculated.

The coordinates of the virtual camera 1 1 are:

Steps d) and e) are then repeated so as to display an image of the environment 17 and a representation of the vehicle 1, seen from a distance to the vehicle 1 corresponding to the wish of the user.

The virtual image 13 comprising the environment 17 of the vehicle 1 as well as the representation 15 of the vehicle 1 is thus composed and displayed after each deduction of the new posture of the virtual camera 11.

Alternatively, the virtual image 13 could be composed and displayed only after the driver has selected the three selected points P1, P2, P3. For this purpose, by combining the coordinates of the virtual camera calculated from the first selected point P1, the second selected point P2 and the third selected point P3, a set of final coordinates (Xcamf, of the virtual camera 1 1:

According to a variant of the display method, the calculation unit 9 could control the simultaneous display of the first graphic element 19, second graphic element 21 and third graphic element 23 previously described, during the display step a).

The user could then choose with precision the new posture of the virtual camera 11 by choosing a point on any one of the first, second and third graphic elements 19, 21, 23.

Thus, the acquisition of the first, second and third selected points P1, P2, P3 could be performed in any order. Therefore, the user could select in any order the height of the virtual camera 1 1, the rotation angle Θ of the virtual camera 11 and the horizontal distance R2 between the virtual camera 11 and the vehicle 1.

Advantageously, the first graphic element 19, the second graphic element 21, and the third graphic element 23 each have a different color.

In addition to the invention, the computing unit 9 can implement an automatic method for determining the posture of the virtual camera 11, when the conditions require it.

More precisely here, the computing unit 9 is programmed to automatically modify the posture of the virtual camera 11 when an obstacle is detected near the vehicle 1.

For this, the calculation unit 9 determines the trajectory of the vehicle 1 during a prediction step. The calculation unit 9 determines this trajectory as a function of at least the angle of the steering wheel and the gear ratio engaged (forward or reverse).

Then, during a detection step, the computing unit 9 searches for an obstacle located near the vehicle 1. More precisely, the computing unit 9 determines if an obstacle is on the previously predicted trajectory.

For this, the computing unit 9 uses remote sensors (radar and / or sonar and / or lidar) located around the vehicle 1. For example here, the vehicle 1 is equipped with six remote sensors at the front and six remote sensors at the rear. Remote sensors not only detect the presence of an obstacle, but also assess the distance between the obstacle and the vehicle 1.

If an obstacle is detected on the predicted trajectory, then the user can no longer choose the posture of the virtual camera 11 manually. The choice is made automatically by the calculation unit 9.

If the vehicle 1 moves forward, and an obstacle is detected in its path, then the virtual camera is automatically positioned along the longitudinal axis (OXv) of the vehicle 1 towards the rear of the vehicle 1 , and directed towards the front of the vehicle 1. The virtual camera 1 1 is then placed at an orientation angle θ equal to π radians.

Alternatively, the computing unit 9 could choose the orientation angle Θ from a plurality of rotation angles Θ stored in the memory unit.

Preferably, the computing unit 9 determines the height of the obstacle. The angle of inclination φ of the virtual camera 11 is then calculated so that the optical axis of the virtual camera 11 passes through the center of the obstacle.

The horizontal distance R2 between the vehicle 1 and the virtual camera 1 1 is calculated as a function of the distance detected between the obstacle and the vehicle 1.

The closer the detected obstacle is, and the closer the virtual camera 1 1 seems.

BLANK UPON FILING

Claims

1. A method of displaying an image of the environment of a vehicle (1) on a touch screen (7) fitted to the vehicle (1), comprising steps of:

a) display on said touch screen (7):

an image of the vehicle (1) as seen from a virtual camera (1 1) placed in an initial posture (PosO), and

at least one graphic element (19, 21, 23) associated with a posture parameter of the virtual camera (1 1),

b) acquiring the position of a point (P1, P2, P3) of said graphic element (19, 21, 23) selected by pressing a user on the touch screen (7), c) calculating the value of said posture parameter

according to the position of said point (P1, P2, P3), and deduction of a new posture of the virtual camera (1 1),

d) real image acquisition of the environment by a plurality of image sensors (5),

e) composition, from the actual images acquired in step d), of a virtual image (13) of the environment (17) of the vehicle (1) as seen from the virtual camera (1 1 ) placed in the new posture determined in step c), and

f) display on the touch screen (7) of the virtual image (13).

2. Display method according to the preceding claim, wherein there is provided a step of constituting a representation (15) of the vehicle (1) as it would be seen from the virtual camera (1 1) in the new posture determined in step c), and wherein, in step e), the virtual image (13) is obtained by superimposing the representation (15) of the vehicle (1) to the environment (17).

3. Display method according to one of the preceding claims, wherein said graphic element (19, 21, 23) comprises a circle located around the image of the vehicle (1) and said posture parameter (Θ) is a orientation angle (Θ) of the virtual camera (1 1) around the vehicle (1).

4. Display method according to the preceding claim, wherein said graphic element (19, 21, 23) makes it possible to select the orientation angle (Θ) of the virtual camera (1 1) around the vehicle (1) with a step of 1 degree.

5. Display method according to one of the preceding claims, wherein said graphic element (19, 21, 23) comprises a segment located vertically with respect to the image of the vehicle (1) and said posture parameter (Θ, Zcam, R2) is a vertical distance (Z _ca m) between the vehicle (1) and the virtual camera (1 1).

6. Display method according to one of the preceding claims, wherein said graphic element (19, 21, 23) comprises a segment located horizontally relative to the vehicle image (1) and the posture parameter (Θ, Zcam, R2) is a horizontal distance (R2) between the vehicle (1) and the virtual camera (1 1).

7. Display method according to one of the preceding claims, wherein steps c) to f) are repeated after each point support exerted by the user on the touch screen (7).

8. Display method according to one of the preceding claims, wherein, the virtual camera (1 1) having an optical axis (A ₀ ), in step c), the new posture of the virtual camera (1 1 ) is defined such that said optical axis (A ₀ ) passes through a predetermined point of the vehicle (1).

9. A vehicle driving aid system comprising:

four image sensors (5), each of the four image sensors (5) being placed on one of the four sides of the vehicle (1), each of the four image sensors (5) being able to acquire a real image the environment of the vehicle (1),

a touch screen (7), and

a calculation unit (9) programmed to implement a method display device as defined in one of the preceding claims.