Method for projecting an image onto a road surface

Abstract

The invention relates to a method for projecting an image (B) onto a road surface in front of a vehicle (1) by means of at least one headlight (1.1) of the vehicle (1), wherein a situation- and / or function-dependent image (B) is projected onto the road surface at least for one occupant of the vehicle (1) and / or for at least one road user in the immediate vicinity of the vehicle (1). According to the invention, it is provided that - a viewing direction of at least one occupant of the vehicle (1) is determined on the vehicle side, - a viewing direction of at least one road user is determined on the vehicle side and - depending on a given situation, the image (B) is projected onto the road surface in a targeted manner according to the determined viewing direction of at least one occupant and at least one road user.

Description

[0001] The invention relates to a method for projecting an image onto a road surface.

[0002] DE 10 2048 120 330 A1 discloses an image projection system for vehicles. A computer is programmed to activate a light source to project a symbol from the vehicle outward. Furthermore, the computer is programmed to activate the light source to modify the projection based on a determination that the vehicle's trajectory is changing.

[0003] DE 10 2009 045 169 A1 describes a display device for a vehicle and a method for displaying image information in a vehicle. The method provides for an image to be generated and projected onto a combiner surface, and for a driver's head and / or eye and / or pupil position and / or gaze direction to be detected. Furthermore, upon detection of a driver's head and / or eye and / or pupil position and / or gaze direction, the positions of image objects of a first object category are changed such that the image objects appear contact-analogous to real objects in the driver's field of vision.Positions of image objects of a second object category are changed independently of real objects around the driver's field of vision in such a way that the driver has the impression that the image objects are located at a distance in front of the combiner surface that is less or greater than the distance of an image plane of the virtual image from the combiner surface.

[0004] DE 10 2009 048 619 A1 describes a method for controlling the headlights of a vehicle with a headlight and a sensor for detecting objects. When there is a risk of collision with an object, a special function of the headlights is activated. A first light source of the headlight, formed from one or more LEDs, is alternately activated and deactivated, and a second light source, formed from one or more LEDs, is controlled in such a way that flashes of light are generated. An optical axis of the second light source is aligned with the object.

[0005] The invention is based on the object of specifying a method for projecting an image by means of at least one headlight of a vehicle.

[0006] The object is achieved according to the invention by a method which has the features specified in claim 1.

[0007] Advantageous embodiments of the invention are the subject of the subclaims.

[0008] The method according to the invention for projecting an image onto a road surface in front of a vehicle by means of at least one headlight of the vehicle is characterized in that - a situation- and / or function-dependent image is projected onto the road surface for at least one occupant of the vehicle and / or for at least one road user in the immediate vicinity of the vehicle, - a viewing direction of at least one occupant of the vehicle is determined on the vehicle side, - to determine a viewing point, a position of a head of the occupant is determined based on a seating position, including a position of a headrest of a vehicle seat on which the at least one occupant is sitting, and / or based on a weight of the at least one occupant, wherein the seating position is given a higher weighting to determine the position of the head of the at least one occupant, - a viewing direction of at least one road user is determined on the vehicle side, - depending on the situation, the image is projected onto the road surface in a targeted manner according to the determined viewing direction of at least one occupant and at least one road user, and - an image to be projected according to the current situation is stored in a memory unit of the vehicle, so that a perspective transformation for an image matrix of the headlight is determined for projecting the image onto the road surface.

[0009] By applying the method, the projected image is projected onto the road surface in front of the vehicle in such a way that the projected image can be recognized and perceived according to its meaning, in particular clearly, by a person, for example a driver of the vehicle, to whom an instruction presented by the projected image is directed. Determining the perspective transformation for the image matrix of the headlight for projecting the image onto the road surface based on the image stored in the vehicle's memory unit and to be projected according to the current situation makes it possible to project the image onto the road surface in such a way that the projected image is hardly or not at all distorted from the respective viewing direction of a respective person, and can thus be recognized and perceived according to its meaning.

[0010] In one embodiment, if the image to be projected is to be seen by both the at least one occupant and the at least one road user, a geometric center, in particular an angle bisector, is used to position the image to be projected on the road surface between the determined viewing direction of the at least one occupant and the at least one road user. This ensures that the projected image is substantially, in particular clearly, recognized and perceived by the occupant, in particular the driver, and the at least one road user, for example, a pedestrian on a vehicle's roadway.

[0011] In a further embodiment of the method, the viewing direction of at least one vehicle occupant is determined based on captured image data from an interior camera of the vehicle, and the viewing direction of at least one road user is determined based on captured image data from an exterior camera of the vehicle. The respective viewing direction is thus determined based on the respectively captured image data, whereby an actual viewing direction of the at least one vehicle occupant and of the at least one road user is detected. The respectively captured viewing direction forms a basis for projecting the image so that it can be recognized and perceived according to its significance by the at least one vehicle occupant and / or by the at least one road user in the immediate vicinity of the vehicle.

[0012] In a further development, a viewing point for projecting the image onto the road surface is determined based on the geometric center of a pair of eyes of the at least one occupant and / or the at least one road user. Thus, a viewing point is determined that forms a reference point for projecting the image onto the road surface, ensuring that the at least one occupant and / or the at least one road user recognizes and perceives the projected image. This determination of the head position can be used additionally, in particular for plausibility checks.

[0013] Furthermore, in one embodiment, a distance between a vehicle front and a position of the image to be projected on the road surface is specified, wherein an angular range for the eye of at least one occupant of the vehicle is determined based on an aspect ratio, in particular a display aspect ratio, of the image to be projected. Target corner points of the projected image are determined based on the angular range, in particular to reduce distortion of the projected image. Thus, it can be largely ensured that the projected image is recognized and perceived.

[0014] In a possible further development, the target corner points are transmitted to at least one headlight, pixel coordinates of these target corner points are determined, and a transformation matrix is ​​determined based on the pixel coordinates, which is used to adjust the image to be projected accordingly. The image to be projected is adjusted, in particular, based on the transformation matrix so that the projected image can be seen precisely, for example, by a driver of the vehicle.

[0015] Furthermore, the system provides for the vehicle to determine the relevance of the image projected onto the road surface based on the current situation. The image projected onto the road surface is positioned accordingly. For example, a roadwork warning is projected onto the road surface in such a way that the image is recognizable and perceivable in its meaning by the driver as a passenger and, if applicable, by other vehicle occupants.

[0016] A lane change indicator, on the other hand, is an additional image projected onto the road surface for a road user, for example, in the area of ​​a lane into which the vehicle intends to change. The projection is performed in such a way that the image indicating the lane change indicator can be recognized and perceived by both the vehicle's occupants and the road user.

[0017] In a possible further embodiment, the number of vehicle occupants is determined based on signals detected by a respective seat occupancy sensor and / or based on the respective seat belt buckle status. This determines whether additional occupants need to be considered in addition to the driver to project a situation-dependent image onto the road surface.

[0018] Embodiments of the invention are explained in more detail below with reference to a drawing.

[0019] The following shows: Fig. 1 schematically shows a perspective view of a vehicle and an image projected onto a road surface.

[0020] The single figure shows a road section F with a vehicle 1 traveling in a lane F1. By means of at least one headlight 1.1 of the vehicle 1, an image B, according to the present embodiment a construction site notice, is projected onto the road surface at a predetermined distance in front of the vehicle 1. In particular, a driver of the vehicle 1 is made aware by means of the projected image B that there is a construction site some distance from the vehicle 1. Alternatively or additionally, the driver of the vehicle 1 can be made aware by means of the projected construction site notice that he is in a construction site area and is currently driving through it. For this purpose, the headlights 1.1 of the vehicle 1 are high-resolution and have a number of so-called LED pixels.

[0021] In general, such an auxiliary and warning projection of images B, in particular symbols, by high-resolution headlight systems is known, wherein the projection takes place regardless of a position of a driver and / or other occupants of a vehicle 1 and / or regardless of a road user in the immediate vicinity of a vehicle 1, so that depending on an eye and / or head position of a respective person, it is possible that this person cannot recognize or perceive the image B.

[0022] The following describes a method which provides for the image B to be projected onto the road surface in such a way that one or more persons to whom the image B, in particular its meaning, is intended can essentially accurately recognize the projected image B and thus perceive its meaning. In particular, the projection of an image B onto the road surface serves to support or warn occupants of a vehicle 1 and / or road users in the immediate vicinity of the vehicle 1, in particular in front of the vehicle 1.

[0023] Projectable images B can be designed in a variety of ways, with the projectable images B being divided into two categories in particular. Projectable images B intended for passengers of vehicle 1, in particular a driver, are assigned to one category, and projectable images B intended additionally for road users in the vicinity of vehicle 1 are assigned to another category.

[0024] Projectable images B intended for passengers, in particular a driver of vehicle 1, are, for example, an indication of a work site / construction site, as in Fig. 1, and a warning for slippery conditions.

[0025] A projectable image B intended for road users and passengers of the vehicle 1 is a lane change indication, wherein in addition a so-called spotlight with an additional warning symbol can be generated by means of at least one headlight 1.1 of the vehicle 1 in order to mark a road user because he is on or near the lane F1 of the vehicle 1 or in a comparatively insufficiently visible section of the road section F.

[0026] With regard to image projections intended for the driver of the vehicle 1 or the driver and a passenger or all occupants of the vehicle 1, a projection of a respective image B is adapted depending on the occupants of the vehicle 1 to whom the projected image B is intended, as described below.

[0027] To project an image B intended for the driver of vehicle 1, the driver's eye position is determined based on signals acquired by a sensor system installed on the vehicle. For example, the driver's gaze direction is determined based on image signals acquired by an interior camera, such as an eye-tracker camera and / or time-of-flight sensors. The driver's viewpoint is then determined in relation to a geometric center of both eyes, i.e., a pair of eyes.

[0028] Alternatively or in addition to determining the driver's line of sight based on captured image signals, the position of the driver's head is determined, whereby the viewing point is also specified based on the geometric center.

[0029] Alternatively or additionally, the head position of the driver of vehicle 1 is estimated based on two pieces of information that can be determined from the vehicle. One piece of information represents a seat adjustment and headrest position of a vehicle seat on which the driver is sitting, whereas another piece of information represents the driver's weight. Greater emphasis is placed on the seat adjustment, for which a weighting factor can be specified. If the weighting factor is 1, only the seat position is considered to estimate the driver's head position.

[0030] Regarding the driver's weight, their height is determined using a body mass index table, with the average body mass index for a normal-weight person being 21.75. The height is then converted into a height, fore / aft, and lateral position using the seat shape of a specific vehicle series.

[0031] If information about the vehicle seat's adjustment is available, a value from the seat adjustment can be used as the basis for a more specific determination of the driver's head position. If the information about the seat adjustment is not available on the vehicle side, a determined weight value is used exclusively to determine the driver's head position. If the weight value is not available, the seat adjustment is used exclusively to determine the head position.

[0032] If neither the information on the seat position nor the weight of the driver is available, the position of the driver's head for vehicle 1 is determined based on a typical average position in the direction of a vehicle vertical axis, a vehicle longitudinal axis and a vehicle transverse axis, which is commonly used.

[0033] The possible projectable images for supporting and / or warning the driver, other occupants of the vehicle 1 and / or road users in the immediate vicinity of the vehicle 1 are stored in a memory unit of the vehicle 1, optionally with additional information, such as an aspect ratio, in particular a display aspect ratio, of the image B to be projected. Based on this, a perspective transformation for an image matrix of the headlight system can be determined so that the driver of the vehicle 1 sees the projected image 1 exactly.

[0034] For example, a position, i.e., a distance between a vehicle front and a position of the image B to be projected onto the road surface, is specified. Based on the aspect ratio and the determined viewing direction of the driver of vehicle 1, an angular range for the driver's eye is known, so that target corner points E of the image B to be projected onto the road surface can be determined. Subsequently, the determined target corner points E are transmitted to the headlights 1.1 of vehicle 1, thus determining pixel coordinates of the target corner points E. This calculates the transformation matrix, and the image B to be projected is adjusted.

[0035] If the image B to be projected is intended for the passenger in addition to the driver, a viewing direction of the passenger and / or a position of his head is determined, as described with regard to the driver.

[0036] In this case, the direction of view and / or the position of the front passenger's head is only determined if it is determined that a front passenger is in the vehicle 1, for example based on image signals recorded on the vehicle side and / or based on signals recorded by a seat occupancy sensor and / or based on a belt buckle status of a belt buckle assigned to the front passenger.

[0037] Subsequently, it is determined whether the image B to be projected can be split or duplicated. If the image B to be projected can be duplicated, the projection is duplicated so that a projected image B is projected onto the road surface in the direction of view of the driver and the same image B is projected onto the road surface in the direction of view of the front passenger. The respective projection is adjusted according to the respectively determined direction of view so that the respective projected image can be recognized and perceived by both the driver and the front passenger. The two images B are projected onto the road surface by means of a headlight 1.1, whereby it can also be provided that the projection of both images B is split using both headlights 1.1.

[0038] In an alternative or additional embodiment, image-dependent, particularly symbol-dependent, metrics are used. These evaluate distortions at individual points and sections of images B to be projected and project them onto the road surface in such a way that relatively important areas of image B are depicted as ideally as possible for viewers, especially the driver and passenger, while deviations in other areas are accepted. In such a case, different results may be obtained than with the adjustment with respect to the geometric center.

[0039] If there are more than one occupant in the vehicle 1 other than the driver and the front passenger, an average is calculated, in particular with respect to the geometric center, of the viewing directions of the pairs of eyes of all occupants of the vehicle 1, so that each occupant can see the projected image B with the least possible distortion.

[0040] The occupants, particularly in the rear area of ​​vehicle 1, are identified based on captured image signals, for example, from the interior camera, based on captured signals from a respective seat occupancy sensor, and / or based on a respective seat belt buckle status. If the image B to be projected cannot be duplicated, the geometric center can be determined with respect to the viewing direction of all occupants of vehicle 1. Alternatively, it can be provided that only the viewing direction of an occupant sitting centrally in the rear area is taken into account, since this centrally seated occupant is normally the only occupant who can actually see the image B projected onto the road surface.

[0041] The image projection can also be duplicated, as described above, whereby a potential centrally seated occupant is assigned to a left or right longitudinal area of ​​the vehicle. Here, too, the adaptation of the projected image B can be refined using symbol-dependent metrics.

[0042] A projection of an image B, which is also intended to be visible to a road user in the vicinity of the vehicle 1 and / or whose recognizability by other road users provides the vehicle 1 with an advantage, in particular taking into account the other road users, is described below.

[0043] One embodiment of this is Spotlight, by means of which pedestrians and cyclists are marked who are on or relatively close to the lane F1 of the vehicle 1 and / or in an insufficiently visible section of the road section F.

[0044] For example, a light band is projected from vehicle 1 toward the road user, with a warning symbol related to the road user also projected into the light band. For example, a flashing exclamation mark can be integrated into the projected light band, which is displayed in a manner adapted to the position of the road user's head. For example, viewed from vehicle 1, the exclamation mark appears as if it is on the road user's head. The projection calculation is performed as described above.

[0045] A further embodiment for projecting an image B, which is intended for the occupants of the vehicle 1 and the road users in the vicinity of the vehicle 1, forms the lane change indication, for example in highly automated or autonomous driving operation of a vehicle 1.

[0046] When changing lanes, for example, to the right, an image B, such as an animated graphic, is projected onto the road surface. Specifically, this image B is projected onto a lane marking between the vehicle lanes F1 that affect the lane change.

[0047] This projection can, for example, be adjusted so that the image B to be projected is projected onto the lane to which the vehicle is to change, relative to the position of another vehicle behind or next to vehicle 1. Alternatively, the projection is performed depending on the geometric center of the determined viewing directions of the occupants of vehicle 1.

[0048] The position of the other vehicle is determined using sensor fusion. If so-called bounding boxes are present, the position of the driver's head is placed within them based on these dimensions.

[0049] The bounding box provided by sensor fusion represents a cuboid in which the vehicle is located. The direction of travel, speed, etc., are usually also known. Here, it is possible to define the approximate average head positions of the drivers within a "vehicle cuboid." This naturally depends on the vehicle type, but can be approximated, e.g., with a position of 0.7 for the longitudinal extent, 0.8 for the vertical axis extent, and 0.2 or 0.8 for the lateral extent (depending on left- / right-hand traffic), with a length scale normalized to 1 in each case.

[0050] This will not be exactly correct, but the errors will be almost irrelevant for visibility / perception because they will be small enough.

Claims

[1] Method for projecting an image (B) onto a road surface in front of a vehicle (1) by means of at least one headlight (1.1) of the vehicle (1), wherein - a situation- and / or function-dependent image (B) is projected onto the road surface at least for one occupant of the vehicle (1) and / or for at least one road user in the immediate vicinity of the vehicle (1), - a viewing direction of at least one occupant of the vehicle (1) is determined on the vehicle side, - to determine a viewing point, a position of a head of the occupant is determined based on a seating position, including a position of a headrest of a vehicle seat on which the at least one occupant is sitting, and / or based on a weight of the at least one occupant, wherein the seating position is given a higher weighting to determine the position of the head of the at least one occupant, - a viewing direction of at least one road user is determined on the vehicle side, - depending on the situation, the image (B) is projected onto the road surface in a targeted manner according to the determined viewing direction of at least one occupant and at least one road user, and - an image (B) to be projected according to the present situation is stored in a memory unit of the vehicle (1), so that a perspective transformation for an image matrix of the headlight (1.1) for projecting the image (B) onto the road surface is determined. [2] Method according to claim 1, characterized bythat if the image (B) to be projected is to be seen by both the at least one occupant and the at least one road user, a geometric center is used to position the image (B) to be projected on the road surface between the determined viewing direction of the at least one occupant and the at least one road user. [3] Method according to claim 1 or 2, characterized by that the viewing direction of the at least one occupant of the vehicle (1) is determined on the basis of captured image data from an interior camera of the vehicle (1) and the viewing direction of the at least one road user is determined on the basis of captured image data from an exterior camera of the vehicle (1). [4] Method according to one of the preceding claims, characterized bythat a viewing point for projecting the image (B) onto the road surface is determined based on a geometric center of a pair of eyes of the at least one occupant and / or the at least one road user. [5] Method according to one of the preceding claims, characterized by that a distance between a vehicle front and a position of the image (B) to be projected on the road surface is predetermined, an angular range for the eye of the at least one occupant of the vehicle (1) is determined on the basis of an aspect ratio of the image (B) to be projected, wherein target corner points (E) of the projected image (B) are determined based on the angular range. [6] Method according to claim 5, characterized bythat the target corner points (E) are transmitted to the at least one headlight (1.1), pixel coordinates of these target corner points (E) are determined and a transformation matrix is ​​determined on the basis of the pixel coordinates and the image (B) to be projected is adapted accordingly on the basis of the transformation matrix. [7] Method according to one of the preceding claims, characterized by that, based on the current situation, the vehicle determines the relevance of who the image (B) projected onto the road surface applies to. [8] Method according to one of the preceding claims, characterized by that a number of occupants of the vehicle (1) is determined based on detected signals from a respective seat occupancy sensor and / or based on a respective belt buckle status.

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