The present invention relates to a method for reproducing an image on a turfed area, such as a natural-grass playing field in a stadium, on a racecourse, a golf course, etc.
Methods and devices for making such markings on a turfed area already exist.
Thus, document WO-200228541-A describes a mobile device comprising a marking head provided with nozzles and electronic means which control these nozzles according to the position of this mobile device at a given time, in accordance with the pattern to be reproduced. The position of the vehicle on the surface is tracked, and the nozzles controlled, by a global positioning system (GPS) after the coordinates of the surfaces to be marked have been entered.
Such a device may only be implemented if the satellite links with the vehicle are satisfactory. However, this is not the case for a vehicle placed on a field surrounded by stands, as these hinder the proper functioning of the GPS (“Global Positioning System”).
Document US-20120253613-A describes a method and a device for creating visual effects on a turfed area. High-resolution images are marked on lawns and fields using a global positioning system, a processor to generate the desired pattern which is translated into printing instructions, and a modeling tool which is used to generate detailed patterns and to mark these patterns on a lawn, a natural or artificial field, or more generally on a turfed area.
These known methods and devices allow a pattern to be reproduced on a turfed area which is approximately flat or appears to be so from a distance, such as a stadium field. However, with these methods and devices, an observer in the stadium will see the pattern from a certain angle which causes this image to be distorted. The same will be true in the case of a television camera: the image that will appear will be distorted and will not perfectly reflect the logo, typography, design or pattern desired.
Likewise, the altimetric shape z(x, y) of the turfed surface at the level of the marking area will have a more or less substantial image distortion effect, which may be relatively marginal for the shape of a stadium field (like a roof, single-pitch roof, etc.) but which may be significant in the case of a golf fairway.
In addition, as indicated above, the use of a GPS system to guide the vehicle and control the marking means is not possible for turfed surfaces surrounded by stands, such as large international stadia.
In addition, with a view to patterns such as brand logos to be produced repeatedly in a large number of stadia, potentially remote and different from one another, and, simultaneously, in the context of a sports competition for example, it is necessary for these patterns to be produced in a fast, repeatable, reliable and precise manner. The pattern therefore has to be produced in particular in the right place on the field, at the right scale, and so as to take into account the specificities of the stadium (size and slopes of the field, location of the cameras, plant varieties constituting the turf, etc.) However, the known methods and devices do not allow markings to be produced in such a way in a simple, fast, reliable, automated and autonomous manner. There is a lack of a method incorporating all of the means and steps for producing markings in such a way, starting with the definition of the parameters needed to obtain the same desired visual result for the marks, in an identical manner for each match or sport-peripheral event, despite the specificities of each stadium.
There is a known method used at the present time to simultaneously take into account the distortion due to the altimetric shape of the field and to the precise point of observation of the image while scaling and siting the image correctly.
Thus, document FR-2785230-A describes a method consisting in projecting the image to be reproduced on the area of the ground on which it is intended to reproduce this image, by means of a light projection means positioned at the exact location of the observation point intended for the camera. The advantage of the method is that the projected image is spontaneously deformed into anamorphosis; if this projected image were painted on the ground in the same pattern, it would naturally be seen from the observation point with the shape of the image initially projected, simply because the projection rays or light rays emitted from the image projected or marked on the field follow exactly the same rectilinear paths between the projected image and the camera or projector.
This prior method also includes forming the “characteristic contours” of the pattern on the ground, which should then serve as guides for the application of marking means. However, this method has substantial limits. In addition to the fact that such a method requires, prior to marking, a night-time projection of an outline and the identification of characteristic contours on the field, if present, most importantly this method does not in any way provide the marking instructions according to the position of the vehicle: indeed, it only makes it possible to visually follow an outline identified by guides positioned on the field, contrary to the desire according to the invention to automate the method in a single step according to a real-time measurement of the position of the vehicle, independently of its path.
The present invention has, on the contrary, the objective of providing a method for reproducing a pattern on a turfed area by means of a device comprising a vehicle provided with marking means, which makes it possible to control these marking means according to the position of the vehicle rather than by requiring the vehicle to visually follow one or more paths previously set out on the ground during a night-time projection of the image.
Therefore, one of the objects of the present invention is to provide a method for reproducing a pattern on a turfed area by means of a device comprising a vehicle provided with marking means, which makes it possible to control the marking means without having to use a global positioning system. Optionally, this method will also make it possible to guide this vehicle.
Another object is to provide a method that makes it possible to compensate for the optical distortions created by the shape of the field and the location of the cameras, which vary according to the stadium.
These objects, as well as others which will become apparent later, are achieved by means of a method for reproducing a pattern to be marked on a large-sized turfed area using a vehicle comprising a set of marking means, which method is, according to the present invention, characterized in that it comprises the following steps:
Preferably, the method comprises the following additional steps:
Advantageously, the point of origin (O) of the local coordinate system is located on or near the marking area.
According to a preferred embodiment of the present invention, the method further comprises the following steps:
According to this preferred embodiment of the present invention, the method therefore comprises the following additional steps:
In a less precise but particularly practical way, the method according to the invention described above comprises simple parametric calculations in which the altimetric curve z(x, y) is replaced by various preset parametric curves z′(x, y): by default by a constant horizontal plane z=0 at the level of the turf or by a roof shape described by the coordinates of the ridge (by default the median longitudinal axis) and the pitch of the roof as %, or by a single pitch described by its pitch as % and its pitch line.
Advantageously, the method further comprises the step of determining the position and orientation of the vehicle in the local coordinate system by means of an optical telemetry device including a laser source emitting from the point of origin (O) of the local coordinate system and a reflecting tracking prism located on the vehicle.
Preferably, the marking means consist of compressed air nozzles that make it possible to bend the leaves or blades of grass in one direction or another, and of rollers, arranged after these nozzles in the direction of travel of the vehicle (V), to fix the orientation of the leaves or blades of grass.
The following description, which is in no way limiting, of one exemplary embodiment of the present invention should be read with reference to the appended figures, which show:
In
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The present invention relates to a method for reproducing, in a rectangle of a turfed area, such as the natural-grass surface of a playing field, a large-sized pattern such as, for example, an advertising pattern. This reproduction or marking is performed by means of a vehicle (V) comprising in particular a set of marking means, and comprises the following steps:
In addition, the turfed surface may be digitized with respect to this local coordinate system: this digitization may concern all of the fields on which patterns are likely to be marked, thus allowing a fast, precise and reproducible operation.
According to this method, the fact of being able to digitize all of the playing fields on which patterns might be marked with respect to a local coordinate system specific to each field affords the method great freedom of implementation.
This method may include the following additional steps:
This method also makes it possible to make a marked pattern (D) visible from a predetermined observation point (A) without distortion: that is to say that an observer located at this observation point (A) will see the pattern as if they were positioned perpendicular to the plane of that pattern. This observer may be, for example, a television camera.
As shown in
It should be noted that the solid angle (S) decreases as the point (A) moves from the point (A1) located vertically from the pattern (D) towards the plane of the field.
Likewise, if the point (A1) is moved along a vertical to the pattern (D) away from this pattern (D), the solid angle (S1) at which this pattern (D) is viewed decreases. Thus, when the point (A1) is at the distance (R) from the pattern (D), the solid angle (S1) is larger than the solid angle (S′1) for an observation point (A′1) located on the same vertical as the point (A1) but at a distance greater than the distance (R).
To calculate the distortion to which to subject the pattern (D) so as to be seen by an observer located at the point (A) as if this observer were located vertically in line with the pattern (D), it is therefore necessary to know the dimensions of the pattern (D), the distance (R) at which the point (A) is located from the pattern (D) and the zenith angle (Z) for the point (A): thus three parameters are needed to determine how the observer located at the point (A) sees the pattern (D). However, it is also necessary to determine at which solid angle (S1) it is desired to view the pattern (D). Once these four parameters have been determined, it is possible to calculate the distorted image of the pattern (D) to be marked in order to compensate for the distortion due to the relative position of the observation point (A) with respect to the quadrangle in which this distorted image will be marked.
As shown in
On this field (T), a rectangle (Q) is delimited which constitutes the area to be marked in which the pattern to be marked will be marked, and the coordinates of each vertex (X1, Y1), (X2, Y1), (X1, Y2) and (X2, Y2) of which in the local coordinate system are determined.
The rectangle (Q), that is to say the area to be marked, is partitioned into elementary cells of dimension dx and dy so as to constitute a matrix (M) of m rows and n columns with n.dx=X2−X1 and m.dy=Y2−Y1.
Regarding the pattern to be marked, it is broken down into a mosaic of pixels associated with the elementary cells of the matrix (M) and, for each elementary cell of the matrix (M), tasks to be performed by the marking means are determined according to a pixel value associated with this elementary cell in order to mark the pattern to be marked on the marking area (Q).
The set of marking means is arranged on a vehicle (V) which is guided in the local coordinate system. These marking means may consist of compressed air nozzles that make it possible to bend the leaves in one direction or another, and rollers, arranged after these nozzles in the direction of travel of the vehicle (V), to fix the orientation of the leaves.
The position of the vehicle (V) is measured and its movement is oriented on the field (T) and more particularly on the area to be marked, for example, using an optical telemetry means including a laser source emitting from the point of origin (O) of the local coordinate system and a reflecting tracking prism located on this vehicle (V).
However, when this pattern to be marked or source pattern is viewed from a target observation point (A) located high up and at a certain distance from the rectangle (Q), for example in a stand (B) at the edge of the field (T), it is viewed with a certain degree of distortion. This is for example the case when this target observation point (A) is a television camera. This distortion may make the marked pattern difficult for a television viewer to read and even make it unreadable for the viewer.
According to one embodiment of the present invention, the coordinates (XA, YA, ZA) of the target observation point A in the local coordinate system (O; x, y, z) are determined.
On the basis of the coordinates of the target observation point (A) and the coordinates of the area to be marked (Q), it is possible to determine the target pattern which will be marked in this marking area by the marking means. The target pattern will thus be seen from the target observation point (A) as if the source pattern were seen from a source observation point (A1) located perpendicular to the marking area and at a predefined distance therefrom.
Therefore, for each pixel of the source pattern, a solid angle for the pixel viewed from the target observation point (A) is equal to the solid angle for an area of the source pattern viewed from the source observation point (A1).
In the exemplary embodiment of the invention described above, the altimetric shape of the turfed surface is not taken into account and there is no need to determine it.
For a particularly precise image and in particular if it is desired or necessary to take the altimetric form z(x, y) into account, the pattern to be marked in order to compensate for a distortion due to the relative position of the target observation point with respect to the marking area and to the altimetric shape z(x, y) of the turfed surface is calculated on the basis of the source pattern such that the image marked on the field is exactly the same as that obtained by projecting the source pattern on the marking area using a light projection means positioned at the exact location of the target observation point.
In this embodiment of the present invention, the method therefore comprises the following additional steps:
In
For a less precise but much easier and much faster execution, the method according to the invention proposes various parametric models of preset altimetric shape z′(x, y) by default.
Thus, in the embodiment presented above, the true altimetric shape z(x, y), if it is not determined more precisely, is replaced by default by a choice of a horizontal plane z=0 or a parametric roof shape described by the coordinates of the ridge (by default the median longitudinal axis) and the pitch of the roof as %, or a single pitch described by its pitch as % and its pitch line.
The transformation of the source pattern into a target pattern may be performed on board the vehicle (V) or in another location: the target pattern is then transmitted to the vehicle by a suitable transmission system, to a receiver element located on this vehicle. The means receiving the target pattern, either from a device having performed the transformation on board the vehicle (V) or from the receiver element, controls the marking means and the movements of the vehicle (V) over the marking area.
Thus, according to the method of the present invention, the operation of the marking means is continually adjusted according to the previously determined matrix of the tasks to be performed for each elementary cell and it is checked that all of the elementary cells of the matrix have been treated correctly; otherwise the vehicle (V) continues to move in the rectangle (Q) and the marking means stay activated.
Number | Date | Country | Kind |
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1851474 | Feb 2018 | FR | national |
Filing Document | Filing Date | Country | Kind |
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PCT/FR2019/050374 | 2/19/2019 | WO | 00 |