METHOD AND HEAD-UP DISPLAY FOR PERSPECTIVE TRANSFORMING AND DISPLAYING IMAGE CONTENT AND VEHICLE

Abstract

Method (100) for perspective transformation and display of a rendered image content by a head-up display, comprising the following steps: - Dividing (101) the image content to be displayed (1), which directly and / or indirectly relates to the operation of a vehicle, into several tiles (2); - Transforming (102) each of the tiles (2) by a perspective transformation (3); - Assembling (104) the individual, perspectively transformed tiles (4) into a transformed image content (5); and - Projection (105) of the perspectively transformed image content (5) onto a projection surface which is assigned to the head-up display, wherein the perspectively transformed tiles (4) are stored in a buffer memory and wherein only the part of the several tiles (2) which contains elements (7, 8, 9, 10) of the image content (1) which have changed with respect to a previously transformed and displayed image content is transformed perspectively (102), and the remaining transformed tiles (4) are loaded from the buffer memory to assemble (104) the perspectively transformed image content (5).

Description

[0001] The invention relates to a method and a head-up display for perspective transformation and display of a rendered image content, as well as a vehicle with such a head-up display.

[0002] Vehicles, especially motor vehicles, generally have devices for displaying information. This information can relate to the vehicle's operating status, such as fuel level, speed, and the status of the lights, as well as to assist the driver in operating the vehicle, for example, by displaying navigation information, parking information, and so on. To display this information as conveniently as possible to the driver, head-up displays are used. These project the information into the driver's natural field of vision, where the driver perceives it visually as a virtual image. The natural field of vision corresponds to the vehicle's immediate surroundings, particularly the road ahead, which are the primary considerations for operating the vehicle.When the information is projected, for example, onto the windshield of the vehicle, the driver can read the information without having to take their eyes off the road, which increases the safety of vehicle use.

[0003] Due to the curvature of the optical elements of the head-up display and the windshield, and the fact that the driver typically views the windshield at an angle, the image of the displayed information is distorted. To present the information to the driver undistorted, i.e., clearly and legibly, the image must therefore be adapted to the optical path from the head-up display's image-generating device, through the optical elements of the head-up display and the vehicle's windshield, to the driver's eye.

[0004] To adapt to the optical path, the information to be displayed is passed as rendered image content to a graphics module (graphics engine), which then transforms the rendered image content. This transformation is designed to compensate for distortion caused in particular by curved optical elements, a curved windshield, and a non-perpendicular viewing angle to the windshield. In other words, the graphics module distorts the rendered image content to allow the observer, especially the driver, to visually perceive a corrected representation of the rendered image content.

[0005] EP 1 460 583 A1 relates to a method for projecting an image onto at least one window surface of a vehicle, wherein the window surface is designed as a rear projection surface, and wherein the image pre-distorted according to a curvature of the window surface is projected onto the window surface.

[0006] It is an object of the invention to provide a method, a head-up display and a vehicle in which the transformation and display of a rendered image content is carried out more flexibly and quickly, and in particular the transformation can be adapted more easily to changes in the beam path, for example by changing the position of the image on the projection surface.

[0007] This problem is solved by the method and the head-up display according to the independent claims, as well as by a corresponding vehicle. Advantageous embodiments of the invention are the subject of the dependent claims. The disclosure of the claims is expressly made part of the description.

[0008] In the inventive method for perspective transformation and display of rendered image content by a head-up display according to a first aspect of the invention, the rendered, i.e., to be displayed, image content is divided into several areas, in particular tiles or rectangles. The tiles, or the image content contained in the individual tiles, are preferably each transformed by a perspective transformation, and the individual, perspective-transformed tiles, or the perspective-transformed image content contained in the perspective-transformed tiles, are combined to form a perspective-transformed image content. The perspective-transformed image content is projected onto a projection surface associated with the head-up display.

[0009] The head-up display according to the invention for perspective transformation and display of rendered image content according to a second aspect of the invention comprises a control unit and a projection unit. In particular, the head-up display according to the invention is configured to perform the perspective transformation and display of rendered image content according to the first aspect of the invention. Preferably, the control unit comprises a first module, which is configured to divide the rendered, i.e., to be displayed, image content into several areas, in particular tiles or rectangles, and a second module, in particular a graphics module, which is configured to transform the individual tiles or rectangles.The system comprises a module that transforms the image content contained in each tile, in particular via a graphics programming interface, and a third module that assembles the individual, perspective-transformed tiles into a transformed image. Furthermore, the projection unit is preferably configured to project the perspective-transformed image content onto a projection surface associated with the head-up display.

[0010] The first, second, and third modules can each be implemented as either hardware or software modules. In particular, one or two modules can be implemented as software modules and the remaining module(s) as hardware modules.

[0011] Preferably, a first, second or third module designed as a software module is executed on one or more processors, in particular main processor or main processors (CPU) of the control unit.

[0012] The vehicle according to a third aspect of the invention has a head-up display according to the second aspect of the invention.

[0013] The features and advantages described in relation to the first aspect of the invention and its advantageous embodiment also apply to the second and third aspects of the invention and their advantageous embodiments, and vice versa.

[0014] The invention is based on the approach of dividing a displayed image, in particular a rendered image content containing information to be displayed, into several areas, for example tiles, especially rectangles or rectangular tiles, and transforming these areas separately with a perspective transformation. In other words, the perspective transformation of the image, i.e., the rendered image content, is performed modularly. Subsequently, the perspective-transformed areas, i.e., tiles, are reassembled into a now perspective-transformed image or image content, which is projected by a head-up display onto a projection surface and can be perceived by an observer, in particular a driver in a vehicle with a head-up display, without distortion, i.e., clearly and recognizably, due to the perspective transformation.

[0015] The perspective transformation of individual tiles is preferably tailored to the specific tile being transformed. If a change in the beam path of the head-up display necessitates an adjustment of the displayed image, i.e., the rendered image content, this can be achieved by adjusting individual perspective transformations. In particular, it is not necessary to adjust each individual perspective transformation, nor is it necessary to adjust a single perspective transformation that transforms the entire displayed image, i.e., the entire rendered image content. This generally requires significant computing power and therefore reduces the frame rate at which the transformed images can be displayed by the head-up display.

[0016] Preferably, the invention makes it possible to dispense with the perspective transformation of individual tiles, provided this is not necessary for a distortion-free display of the composite and transformed image, i.e., the image content. In particular, if only a portion of the displayed image, i.e., the rendered image content, needs to be distorted or corrected by a perspective transformation to adapt to the beam path of the head-up display or the observer's position, the computational effort for perspective distortion or correction can be reduced by the modular perspective transformation, as individual tiles whose image content does not need to be adapted to the beam path are not transformed.

[0017] Preferably, the perspective transformation of individual tiles, i.e., a modular perspective transformation, allows for memory- and computation-time-saving perspective transformations using a graphics module that is preferably widely used and, in particular, runs stably on current microprocessors, especially on different platforms. Furthermore, this graphics module is preferably configured to process vector graphics, especially with hardware acceleration, so that individual vector-based perspective transformations can be performed particularly quickly and efficiently.

[0018] Overall, the invention enables the fast and flexible transformation and display of rendered image content.

[0019] In an advantageous embodiment of the method for perspective transformation and display of rendered image content, each individual tile is transformed perspectively with respect to at least one of the following features: trapezoidal shape, curvature, stretching or compression, rotation, or offset. In particular, each individual tile can also be transformed perspectively by a combination of at least two of these features. This enables reliable adaptation of the displayed image content to the optical path of the head-up display.

[0020] In a further advantageous embodiment of the method for perspective-transforming and displaying rendered image content, adjacent tiles have overlapping image content. Specifically, the overlapping image content has a width of one, two, or three pixels. This ensures that when the perspective-transformed tiles are assembled to form a perspective-transformed image, they also have overlapping perspective-transformed image content, or, in particular, that the edges of the perspective-transformed tiles are flush. This reliably prevents the assembled perspective-transformed image content from having areas that are not covered by at least one perspective-transformed tile and are therefore displayed as color-neutral, especially black or white, pixels.Preferably, this feature of the method also avoids the creation of these areas by applying edge smoothing, in particular by a smoothing filter.

[0021] In a further advantageous embodiment of the method for perspective transformation and display of rendered image content, the image content is in the form of a raster graphic, whereby the perspective transformation shifts individual pixels within a tile. This allows the rendered image content to be divided particularly easily into different areas, especially tiles or rectangles or rectangular tiles, with a predefined number of pixels from the raster graphic being assigned to each area or tile. The perspective transformation shifts the individual pixels of the raster graphic belonging to each tile. Thus, the perspective transformation can be implemented particularly simply.

[0022] Preferably, the raster graphic has a specific color depth, in particular 32, 24, 16, 8, or 4 bits. More preferably, the raster graphic can also have a color depth that lies between these values. More preferably, the raster graphic can also have a color depth that is greater than 32 bits or less than 4 bits. More preferably, different pixels of the raster graphic each have different color depths. In particular, preferably, several contiguous pixels of the raster graphic, each belonging to a single tile, have the same color depth. Particularly preferably, the color depth of a single tile is only as high as necessary for the color-accurate representation of the image content contained in the individual tiles.This means that the rendered image content requires very little storage space, especially in a buffer memory, and the perspective transformations of the tiles can be performed particularly efficiently.

[0023] In a further advantageous embodiment of the method for perspective transformation and display of rendered image content, an interpolation, in particular a linear interpolation, of individual pixels of a tile is performed during the perspective transformation, especially those pixels that border and / or lie between pixels shifted by the perspective transformation. This reliably prevents the creation of areas with pixels to which no color value has been assigned. Preferably, the number of pixels per tile is small, so that individual pixels are not shifted over large distances during the perspective transformation. In this case, a linear interpolation of the pixels lying between those shifted during the perspective transformation yields a perspectively transformed image content whose image, generated by a head-up display, is clear and distinct.Especially without artifacts, it can be perceived visually. Linear interpolation, in particular, causes only minimal computational effort, meaning the load on the processing processor is low, which is why the perspective transformation can be performed quickly and efficiently.

[0024] In a further advantageous embodiment of the method for perspective-transforming and displaying rendered image content, the individual tiles are perspective-transformed by multiplication with a transformation matrix. Multiplication with a transformation matrix is ​​a particularly simple and precise way to perform a transformation. A corresponding perspective transformation can therefore be performed particularly quickly and efficiently, especially by a graphics module. In particular, it is therefore possible to achieve a frame rate of 30 to 90, preferably 45 to 75, and most preferably essentially 60 perspective-transformed images per second for the frame rate at which rendered image content is perspective-transformed.In a particularly advantageous embodiment of the method, it is possible to achieve a value of 90 to 160, preferably essentially 120, perspectively transformed image contents per second.

[0025] Preferably, in matrix multiplication with a transformation matrix, the positions of individual pixels of a tile, in particular the four corner points, which are preferably defined by support vectors, are multiplied by the transformation matrix. Support vectors are vectors that specify the position of a pixel relative to an origin, where the origin can be, in particular, a corner or center point of a tile or of the image, i.e., the rendered image content. Multiplying the support vectors by the transformation matrix shifts the position of the individual pixels of the tile relative to the origin. Preferably, pixels that lie between, and especially adjacent to, these shifted pixels are interpolated, particularly by linear interpolation. This preferably closes gaps in the image content of the perspectively transformed tile.

[0026] Preferably, the number of pixels to be interpolated, particularly linearly, can be determined, and especially limited, by selecting the number or dimensions (i.e., the size or area) of the tiles when dividing the image content to be displayed. This is because, as the number of tiles increases, the number of pixels per tile that need to be perspectively transformed decreases. This ensures that, in particular, linear interpolation of pixels located between shifted pixels, especially those bordering shifted pixels, produces clear and distinct perspectively transformed image content on the tiles or on the composite, perspectively transformed image content to be displayed via the head-up display—that is, perspectively transformed image content without artifacts.

[0027] Preferably, the number or size of the tiles is chosen to be larger than a critical number or size at which the number of pixels to be interpolated, particularly linearly, is so small that artifacts, especially corners, appear in the perspective-transformed image content. This ensures that the composite, perspective-transformed image content displayed via the head-up display does not exhibit any artifacts, especially corners. Preferably, the number and / or size of the tiles is chosen such that the tiles overlap, particularly by one or two pixels each.

[0028] In a further advantageous embodiment of the method for perspective-transforming and displaying a rendered image, the transformation matrix is ​​selected from a plurality of transformation matrices. In particular, the plurality of transformation matrices preferably includes one transformation matrix for each tile to be perspective-transformed. This ensures that the transformation matrices are adapted to the ray path of the image of the respective tile to be perspective-transformed, or, more specifically, that they can be individually adapted to changes in the ray path of the image of the respective tile to be perspective-transformed. Furthermore, the plurality of transformation matrices preferably includes different perspective transformations.

[0029] Any vectorial perspective transformation can be realized through the use of transformation matrices. This allows the perspective transformation to be particularly well adapted to the beam path. A perspective transformation performed with a transformation matrix from the multitude of available transformation matrices preferably involves at least one of the following features: trapezoidal shape, curvature, stretching or compression, rotation, or displacement.

[0030] In a further advantageous embodiment of the method for perspective transformation and display of rendered image content, the perspective transformation of the individual tiles is performed by a graphics module, preferably via a graphics programming interface, in particular OpenVG. Using a graphics module significantly accelerates the perspective transformation of the individual tiles, especially through hardware acceleration, and reduces the computational load on a central processing unit (CPU). Preferably, a graphics programming interface is used that is widely available and provided as standard on microprocessors. Furthermore, the graphics programming interface is preferably available on multiple platforms. Moreover, the graphics programming interface used preferably allows the use of a graphics module that supports hardware-accelerated processing.Provides vector graphics calculation capabilities.

[0031] In a further advantageous embodiment of the method for perspective transformation and display of rendered image content, the perspectively transformed tiles are stored in a buffer memory. The buffer memory allows particularly fast access to the stored perspectively transformed tiles, especially when assembling them into a complete perspectively transformed image or image content to be displayed.

[0032] In a further advantageous embodiment of the method for perspective-transforming and displaying rendered image content, only a portion of the multiple tiles are perspective-transformed, and the remaining transformed tiles are loaded from the buffer memory to assemble the transformed image. This significantly accelerates the assembly of the perspective-transformed image or image content to be displayed. In particular, a frame rate of 30 to 90, preferably 45 to 75, and most preferably substantially 60 perspective-transformed image content units per second can be achieved for perspective-transforming rendered image content. In a particularly advantageous embodiment of the method, a value of 90 to 160, and preferably substantially 120 perspective-transformed image content units per second, can be achieved.

[0033] In a further advantageous embodiment of the method for perspective transformation and display of rendered image content, only the portion of the multiple tiles containing elements of the image content that have changed with respect to a previously transformed and displayed image content is perspective-transformed. Specifically, the remaining perspective-transformed tiles required to assemble the perspective-transformed tiles into a single, perspective-transformed image content to be displayed are loaded from the buffer memory. This ensures, in particular, that a processor burdened by the perspective transformations only processes the parts of the rendered image content that differ from the previously perspective-transformed and displayed image content, i.e., only those parts containing changed information to be displayed.The method incorporates a modified representation of the information to be displayed, which significantly reduces the processing power of this processor compared to performing a perspective transformation of all tiles. This allows the processing power of such a processor to be allocated particularly efficiently for calculations, achieving a frame rate of 30 to 90, preferably 45 to 75, and most preferably substantially 60 perspective-transformed image elements per second for the rendered image content. In a particularly advantageous embodiment of the method, it is possible to achieve a value of 90 to 160, preferably substantially 120 perspective-transformed image elements per second.

[0034] In a further advantageous embodiment of the method for perspective transformation and display of rendered image content, different parts of the multiple tiles have different color depths, in particular 32, 24, 16, 8, and 4 bits. More preferably, different parts of the multiple tiles can also have a color depth that lies between these values. Even more preferably, different parts of the multiple tiles can also have a color depth that is greater than 32 bits or less than 4 bits. In particular, the tiles each have the lowest possible color depth at which the respective image content can still be displayed or rendered with accurate color reproduction, i.e., without any reduction in color quality.Preferably, the perspective transformations, in particular the preferably linear interpolations of individual pixels, of the multiple tiles with different color depths are performed at the respective color depth of the tile to be transformed. This ensures that the perspective transformation or the perspective-transformed tile requires little memory, and the preferably linear interpolation requires little computing power. This allows the perspective transformations, especially the preferably linear interpolations of individual pixels, to be performed particularly quickly and efficiently.

[0035] In a further advantageous embodiment of the method for perspective transformation and display of rendered image content, the multiple tiles are mirrored during the perspective transformation by point or line reflection and combined to form a perspectively transformed, mirrored image. This allows the image orientation of the perspectively transformed image content to be displayed to be adapted to the optical path of the head-up display. In particular, the mirroring eliminates the need for additional optical elements in the head-up display that would otherwise change the image orientation of the perspectively transformed image content for error-free projection onto the head-up display's projection surface, especially by rotating or mirroring it. This results in a particularly simple design for the head-up display.

[0036] Further features, advantages, and applications of the invention will become apparent from the following description in conjunction with the figures. These figures show, at least partially schematically: Fig. 1 an embodiment of the method for transforming and displaying a rendered image content by a head-up display; Fig. 2 a representation of an image content rendered in several tiles using an embodiment of the method according to the invention; Fig. 3 a representation of a perspective transformation of a tile; Fig. 4 a representation of an image content transformed by perspective transformations of individual tiles using an embodiment of the inventive method; Fig. 5 representations of several results of basic perspective transformations; Fig. 6. A representation of a grid and a distorted grid; and Fig. 7 a representation of envelopes of control points on a projection surface.

[0037] Fig. Figure 1 shows an embodiment of the method 100 for transforming and displaying a rendered image content 1 by a head-up display, which is explained below with reference to the other figures.

[0038] Fig. Figure 2 shows a representation of an image content 1 rendered by an embodiment of the method 100 according to the invention, divided into several tiles 2. The image content 1 contains several elements 7, 8, 9, 10, which directly and / or indirectly relate to the operation of the vehicle, in particular traffic rules 7, warnings 8, navigation information 9, and / or speed information 10. Each element 7, 8, 9, or 10 is a part of the entire image content 1. The elements 7, 8, and 9 are preferably displayed and / or represented as pictograms. More preferably, the elements 9 and 10 are displayed and / or represented as characters and / or text, in particular number signs. The image content 1 is preferably rendered so that it exists as a digital image, in particular as a raster graphic.This allows the image content 1 to be easily processed, i.e., changed and / or modified, especially distorted, by digital methods, in particular transformations, preferably perspective transformations.

[0039] The rendered image content 1 is divided into several areas, in particular tiles 2, preferably rectangular tiles 2, in process step 101. More preferably, the tiles 2 are square. In the illustrated embodiment, the edges of the tiles 2 are marked by horizontal and vertical lines 11 for clarity.

[0040] Preferably, individual tiles 2 enclose individual elements 7, 8, 9, 10 or parts of the elements 7, 8, 9, 10, i.e., the part of the total image content 1 contained in the individual tiles 2 represents individual elements 7, 8, 9, 10 or parts of the elements 7, 8, 9, 10.

[0041] Preferably, different tiles 2 have different color depths, in particular 32, 24, 16, 8, or 4 bits. More preferably, different tiles can also have a color depth that lies between these values. More preferably, different tiles can also have a color depth that is greater than 32 bits or less than 4 bits. More preferably, the color depth of a tile 2 is only as high as necessary for a clear and distinct, i.e., color-accurate, representation of the part of the image content 1 contained in the tile 2. In particular, tiles 2 that do not contain elements 7, 8, 9, 10 of the image content 1 have a particularly low color depth, for example, 4 bits or 1 bit. Preferably, tiles 2 that contain monochrome elements 7, 8, 9, 10 or monochrome parts of elements 7, 8, 9, 10, in particular characters or...Text and / or numbers, containing a low color depth, especially 16, 8 or 4 bits, or a value between these values, can be significantly reduced. This allows the storage space required for the rendered image content 1 or the individual tiles 2 to be significantly reduced.

[0042] Fig. Figure 3 shows a representation of a perspective transformation 3 of a tile 2. In process step 102, the perspective transformation 3 generates a perspectively transformed tile 4 from a tile 2, preferably rectangular, in particular square.

[0043] Preferably, the perspective transformation 3 is performed in process step 102 by matrix multiplication, in particular multiplication with a transformation matrix. In this step, the individual pixels, in particular the four corner points, of the tile 2, which is preferably represented as a raster graphic and is specified by support vectors, are multiplied by a matrix that generates a perspective transformation. Support vectors are vectors that specify the position of the pixels with respect to an origin, in particular with respect to one of the four corners of the tile 2 or of the image composed of the tiles 2, i.e., the rendered image content 1, or the center point of the tile 2 or of the image composed of the tiles 2, i.e., the rendered image content 1.

[0044] Through the perspective transformation 3, in particular by multiplying the support vectors with a transformation matrix, the four corner points of the tile 2 are assigned a new position in process step 102 in the illustrated embodiment, indicated by the four dashed arrows 12. In particular, the magnitude, i.e. length, and direction, i.e. orientation, of the support vectors of the image points to be transformed perspectively change.

[0045] If gaps arise between the pixels of the perspectively transformed tile 4 as a result of the perspective transformation 3 in process step 102, these are preferably closed by interpolation, in particular by linear interpolation, in process step 103. Specifically, pixels that border on and / or lie between pixels shifted by the perspective transformation 3 are assigned a value by the interpolation, so that the perspectively transformed tile 4 has a gapless portion of the transformed image content 5, i.e., it can be displayed without artifacts. Preferably, the linear interpolation in process step 103 smooths the perspectively transformed image content so that it can be displayed free of artifacts by a head-up display.

[0046] Fig. Figure 4 shows a representation of a transformed image content 5 composed of an embodiment of the inventive method 100, which was generated in process step 104 by perspective transformations 3 of individual tiles 2 in process step 102. For better clarity, the edges of the perspectively transformed tiles 4 are shown as in Fig. 1 shown by essentially horizontal and essentially vertical lines 11.

[0047] In process step 102, individual tiles 2 are transformed by different perspective transformations 3, in particular different transformation matrices, i.e., modularly, during the perspective transformation 3, and assembled in process step 104 to form a perspectively transformed image content 5. In process step 105, the perspectively transformed image content 5 is preferably projected by a head-up display onto a projection surface associated with the head-up display, where it is visually perceived as an undistorted image by a user, in particular the driver of the vehicle equipped with the head-up display.

[0048] Through the separate, i.e., modular, perspective transformation 3 in process step 102, each perspectively transformed tile 4 preferably acquires a different shape than adjacent perspectively transformed tiles 4. In particular, this results in a closed or continuous, preferably artifact-free, transformed image content 5, which can be represented or displayed as a closed or continuous, preferably artifact-free image. Preferably, the separate perspective transformations 3 transform adjacent tiles 2 in perspective such that their edges are closed, i.e., flush, adjacent to each other. More preferably, a perspective transformation 3 is selected for each tile 2 from a plurality of perspective transformations 3.The perspective transformation 3 is adapted for each tile 2, in particular separately, so that after the perspective transformation 3 and its assembly with adjacent perspective-transformed tiles 4, a closed, artifact-free, perspective-transformed image content 5 results. In particular, the respective perspective transformations 3 for individual tiles 2 are chosen or adapted such that, after assembly to form the perspective-transformed image content 5, no edges, kinks, discontinuities and / or noise appear in the perspective-transformed image content 5 or in the displayable perspective-transformed image.

[0049] Preferably, the rendered image content 1 is divided into tiles 2 with overlapping edges before the perspective transformation 3 in process step 101; that is, a part of the rendered image content 1 is represented by more than one tile 2 or is contained in more than one tile 2. In particular, the edges of adjacent tiles 2 overlap. The overlapping edges, i.e., the overlapping area, can have different widths, in particular 1, 2, 3, or more pixels. Preferably, the width of the overlapping edges is selected or adjusted so that when the perspective-transformed tiles 4 are assembled in process step 104 to form a perspective-transformed image content 5, every area of ​​the perspective-transformed image that can be represented, displayed, and / or mapped by the perspective-transformed image content 5 is covered by at least one perspective-transformed tile 4.This means that the edges of the perspectively transformed tiles 4 do not need to be closed, i.e., flush, against each other, allowing for greater freedom in choosing the appropriate perspective transformations 3 for a single tile 2, or in adapting the perspective transformation 3 to a single tile 2. In particular, perspectively transformed tiles 4 only need to be substantially closed, i.e., flush, against each other.

[0050] Preferably, the overlapping area(s) or edges of the perspective-transformed tiles 4 are smoothed, in particular averaged or interpolated, during assembly in process step 104 to form a perspective-transformed image content 5, such that a seamless transition is achieved between adjacent perspective-transformed tiles 4. This reliably avoids artifacts, in particular edges, kinks, discontinuities, and / or noise in the assembled perspective-transformed image content 5.

[0051] Fig. Figure 5 shows several results of basic perspective transformations.

[0052] Fig. Figure 5A shows the result of a perspective transformation 3, which transforms a rectangular tile 2 into a trapezoidal tile in perspective.

[0053] Fig. Figure 5B shows the result of a perspective transformation 3, which transforms a rectangular tile 2 into a parallelogram-shaped tile using perspective. This is a special case of Fig. 4 A.

[0054] Fig. Figure 5C shows the result of a perspective transformation 3, which transforms a rectangular tile 2 into a curved or barrel-shaped tile with two convex opposite sides.

[0055] Fig. Figure 5D shows the result of a perspective transformation 3, which transforms a rectangular tile 2 into a curved or winding tile with a convex and a concave opposite side. This is a special case of Fig. 5 C

[0056] Fig. Figure 5 E shows the result of a perspective transformation 3, which transforms a rectangular tile 2 into a compressed or stretched tile in perspective.

[0057] Fig. Figure 5F shows the result of a perspective transformation 3, which transforms a rectangular tile 2 into a tile that is rotated, in particular relative to the rectangular tile 2, i.e. rotated by a certain angle.

[0058] Preferably, the perspective transformation 3 of a single tile 2 is composed of several basic perspective transformations 3, the results of which are in Fig. Figures 5 A to F are shown. This makes it possible to select a perspective transformation 3 from a multitude of perspective transformations 3 for each individual tile 2, or to adjust the perspective transformation 3, so that after assembling the perspectively transformed tiles 4 in process step 104, a particularly artifact-free, perspectively transformed image content 5 results, which is in particular free of edges, kinks, discontinuities and / or noise.

[0059] In order to determine how a rendered image content 1 must be perspectively transformed in process step 102 in order to be displayed to the driver of a vehicle in process step 105 as an undistorted image, i.e., how a rendered image content 1 must be adapted to the beam path of the head-up display, i.e., from the image-generating unit of the head-up display via the projection surface to the driver's eye, a regular, in particular regular, grating 13, is distorted so that the distortion corresponds to the adaptation to the beam path.

[0060] Fig. Figure 6 shows a representation of a regular grid 13 (upper part of the image) and a distorted grid 14 (lower part of the image) resulting from the distortion. The grid points 15 of the regular grid 13, represented as crosses, are used or taken into account when dividing the rendered image content 1 into several tiles 2. The grid points 16 of the distorted grid 14, represented as dots, are used or taken into account when selecting the appropriate perspective transformation 3 or when adapting the perspective transformation 3 to a single tile 2 to be transformed perspectively. This reliably ensures that the perspective transformation of the rendered image content 1 in process step 102 corresponds to the adaptation to the beam path of the head-up display.

[0061] Preferably, the distortion of the regular grid 13, i.e., the transformation into a distorted grid 14, is achieved by a perspective transformation 3 or a combination of the basic perspective transformations 3, the results of which are Fig. The 4 shown have been carried out.

[0062] Preferably, the grid points 15 of the regular grid 13 specify the position of the tiles 2. More preferably, the grid points 16 of the distorted grid 14 specify the position of the perspectively transformed tiles 4. In particular, the grid points 15 of the regular grid 13 serve as the starting support points of the tiles 2, preferably as their center point or one of their vertices. In particular, the grid points 16 of the distorted grid 14 serve as the target support points of the perspectively transformed tiles 4, preferably as their center point or one of their vertices.

[0063] Fig.Figure 7 shows a representation of the distribution of regular and distorted grids 13, 14 on an image-generating unit. The image-generating unit is configured to display or map image content on a display 6 in process step 105. Preferably, only a specific transformation area 17 of the display 6, represented by the dashed line, is provided for displaying or mapping the perspectively transformed image content 5. The perspective transformations 3 of the individual tiles 2 are preferably selected or adapted such that, in process step 102, the perspectively transformed image content 5 does not extend beyond the transformation area 17.

[0064] The position of the grid points 16 of the distorted grid 14 preferably lies within a target area 18, represented by a thin dotted line, which is in particular part of the transformation area 17. The target area 18 acts as an envelope for the grid points 16 of the distorted grid or the target support points of the perspectively transformed tiles 4. The target area 18 is preferably smaller than the transformation area 17, since the perspectively transformed tiles 2 have a lateral extension, thus preventing perspectively transformed tiles 4, and therefore parts of the perspectively transformed image content 5, from extending beyond the transformation area 17.

[0065] The position of the grid points 15 of the regular grid 13 is indicated by the output area 19, represented by a solid thin line. The output area acts as the enclosing element of the grid points 15 of the regular grid 13, or the output support points of the tiles 2. The output area 19 is preferably smaller than the transformation area 17, since the position of individual tiles 2 may be shifted towards the edge of the display 6 or the edge of the transformation area 17 by the perspective transformation 3, or the lateral extent of individual tiles 2 may increase. This reliably ensures that the rendered image content 1, divided into several tiles 2, does not extend beyond the display 6 or the transformation area 17 of the display 6 after the perspective transformation 3 and the assembly of the individual tiles 2 into a perspectively transformed image content 5. (if applicable) list of reference symbols 1 rendered image content 2 tiles 3 Perspective Transformation 4 tiles transformed from perspective 5 transformed image content 6 ads 7 traffic rules 8 Warning 9 Navigation information 10 Speed ​​information 11 Tile edge 12 Arrow 13 regular grid 14 distorted grid 15 Grid point of the regular grid 16 Lattice point of the distorted lattice 17 Transformation area 18 Target area 19 Exit area 100 methods for perspective transformation and display of rendered image content via a head-up display 101 Dividing the rendered image content into multiple tiles 102 Perspective transformation of multiple tiles 103 Interpolation 104 Assembling perspectively transformed tiles into a perspectively transformed image content 105 Projection of perspectively transformed image content onto a projection surface by a head-up display

Claims

Method (100) for perspective transformation and display of a rendered image content by a head-up display, comprising the following steps: - Dividing (101) the image content to be displayed (1), which directly and / or indirectly relates to the operation of a vehicle, into several tiles (2); - Transforming (102) the individual tiles (2) by a perspective transformation (3) each; - Combining (104) the individual, perspectively transformed tiles (4) into a transformed image content (5);and projection (105) of the perspectively transformed image content (5) onto a projection surface which is assigned to the head-up display, wherein the perspectively transformed tiles (4) are stored in a buffer memory and wherein only the part of the several tiles (2) is perspectively transformed (102) which contains elements (7, 8, 9, 10) of the image content (1) which have changed with respect to a previously transformed and displayed image content, and the remaining transformed tiles (4) are loaded from the buffer memory to assemble (104) the perspectively transformed image content (5). Method (100) according to claim 1, wherein during transformation (102) the individual tiles (2) are transformed perspectively with respect to at least one of the following features: trapezoidal shape, curvature, stretching or compression, rotation, offset. Method (100) according to claim 1 or 2, wherein adjacent tiles (2) have overlapping image content. Method (100) according to one of the preceding claims, wherein the image content (1) is in the form of a raster graphic. Method (100) according to claim 4, wherein in the perspective transformation (3) an interpolation (103), in particular a linear interpolation, of individual image points of a tile (4), in particular the image points which border on and / or lie between image points shifted by the perspective transformation (3), is carried out. Method (100) according to one of the preceding claims, wherein the individual tiles (2) are transformed perspectively (102) by multiplication with a transformation matrix. Method (100) according to claim 6, wherein the transformation matrix is ​​selected from a plurality of transformation matrices. Method (100) according to one of the preceding claims, wherein the perspective transformation (102) of the individual tiles (2) is performed by a graphics module via a graphics programming interface, in particular OpenVG. Method (100) according to one of the preceding claims, wherein different parts of the multiple tiles (2) have different color depths, in particular 32, 24, 16, 8 and 4 bits. Method (100) according to one of the preceding claims, wherein the multiple tiles (2) are mirrored by point or line reflection during the perspective transformation (102) and assembled to form a perspectively transformed, mirrored image content (5) (104). Head-up display for perspective transformation and display of a rendered image content using a method (100) according to one of the preceding claims, comprising a control unit comprising a first module configured for dividing (101) the image content (1) to be displayed, which directly and / or indirectly relates to the operation of a vehicle, into several tiles (2), a second module configured for transforming (102) the individual tiles (2) by means of a perspective transformation (3), and a third module configured for assembling (104) the individual, perspectively transformed tiles (4) into a transformed image content (5);and a projection unit configured for projecting (105) the perspectively transformed image content (1) onto a projection surface associated with the head-up display, wherein the control unit is further configured to store the perspectively transformed tiles (4) in a buffer memory, and wherein the second module is further configured to perspectively transform (102) only that part of the multiple tiles (2) which contains elements (7, 8, 9, 10) of the image content (1) that have changed with respect to a previously transformed and displayed image content, and wherein the control unit is further configured to load the remaining transformed tiles (4) from the buffer memory to assemble (104) the perspectively transformed image content (5).

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