HK1246955B - Vehicle monitoring system - Google Patents

Description

Vehicle Monitoring System

CROSS-REFERENCE TO RELATED APPLICATIONS

not applicable.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

not applicable.

Background Art

Vehicle monitoring systems are becoming increasingly common as a means of providing situational awareness and collision avoidance. Such vehicle monitoring systems typically include an electronic display for conveying information to a user (e.g., the driver of the vehicle). Specifically, the electronic display can provide a view of the area adjacent to the vehicle to inform the user of objects in the adjacent area and facilitate avoidance of objects in the adjacent area.

Various electronic displays can be used in vehicle monitoring systems, including but not limited to cathode ray tube (CRT) based displays, plasma display panels (PDP), liquid crystal displays (LCD), electroluminescent (EL) displays, organic light emitting diodes (OLED) and active matrix OLED (AMOLED) displays, electrophoretic (EP) displays and various displays that use electromechanical or electrofluidic light modulation (e.g., digital micromirror devices, electrowetting displays, etc.). Generally, electronic displays can be classified as active displays (i.e., displays that emit light) or passive displays (i.e., displays that modulate light provided by another source). The most obvious examples of active displays are CRT, PDP and OLED/AMOLED. Displays that are generally classified as passive when considering the light emitted are LCD and EP displays. Although passive displays often exhibit attractive performance characteristics, including but not limited to inherently low power consumption, they may find somewhat limited use in many practical applications due to the lack of the ability to emit light.

In order to overcome the limitations of passive displays associated with the emitted light, many passive displays are coupled to external light sources. The coupled light source can allow these otherwise passive displays to emit light and essentially function as active displays. An example of such a coupled light source is a backlight. A backlight is a light source (usually a panel light source) that is placed behind an otherwise passive display to illuminate the passive display. For example, a backlight can be coupled to an LCD or EP display. The backlight emits light that passes through the LCD or EP display. The emitted light is modulated by the LCD or EP display, and the modulated light is then subsequently emitted from the LCD or EP display. The backlight is typically configured to emit white light. Color filters are then used to convert the white light into the various colors used in the display. For example, a color filter can be placed at the output of the LCD or EP display (less common) or between the backlight and the LCD or EP display.

BRIEF DESCRIPTION OF THE DRAWINGS

The various features of examples and embodiments according to the principles described herein may be more readily understood by reference to the following detailed description taken in conjunction with the accompanying drawings, in which like reference numerals represent like structural elements, and in which:

FIG1 shows a block diagram of a vehicle monitoring system in an example according to an embodiment consistent with the principles described herein.

2A shows a perspective view of an area monitored using the vehicle monitoring system of FIG. 1 , according to an example of an embodiment consistent with the principles described herein.

FIG. 2B illustrates a side view of the monitored area of FIG. 2B , according to an example of an embodiment consistent with the principles described herein.

FIG. 3A shows a displayed portion of a scanned area in an example according to an embodiment consistent with the principles described herein.

FIG. 3B shows visually highlighted objects in displayed portion 108 of FIG. 3A , in an example according to an embodiment consistent with the principles described herein.

FIG. 3C shows a visually highlighted object in the displayed portion of FIG. 3A , in an example according to an embodiment consistent with the principles described herein.

4 illustrates a perspective view of a 3D electronic display showing a visually highlighted object, according to an example of another embodiment consistent with the principles described herein.

5A shows a cross-sectional view of a three-dimensional (3D) electronic display with a multibeam grating-based backlight, in an example of an embodiment consistent with the principles described herein.

5B shows a cross-sectional view of a three-dimensional (3D) electronic display with a multibeam grating-based backlight, according to an example of another embodiment consistent with principles described herein.

5C shows a perspective view of a portion of a 3D electronic display with a multibeam grating-based backlight, in an example of an embodiment consistent with the principles described herein.

FIG6 shows a block diagram of a three-dimensional (3D) vehicle monitoring system in an example of an embodiment according to the principles described herein.

FIG7 shows a flow chart of a vehicle monitoring method in an example according to an embodiment consistent with the principles described herein.

Certain examples and embodiments have other features in addition to or in lieu of the features shown in the above-referenced drawings.These and other features are described in detail below with reference to the above-referenced drawings.

DETAILED DESCRIPTION

According to embodiments consistent with the principles described herein, a vehicle monitoring system using three-dimensional (3D) information is provided. Specifically, according to some embodiments consistent with the principles described herein, 3D information including 3D scans or images is collected for a monitored area adjacent to a vehicle. For example, the monitored area may be one or more of the front, side, and rear of the vehicle. The 3D information from the monitored area is then used to construct a 3D model of the spatial configuration of objects within the monitored area. In addition, a portion of the monitored area based on the 3D model is displayed, and objects within the displayed portion that are less than a predetermined threshold distance from the vehicle are visually highlighted objects. According to various embodiments, a user's perception of the visually highlighted objects can be enhanced. In addition, for example, the enhanced perception of the visually highlighted objects can promote collision avoidance relative to those visually highlighted objects that are too close to the vehicle.

According to various embodiments, a 3D scanner or 3D camera is combined with an electronic display to function as a vehicle monitoring system to monitor an area adjacent to a vehicle. The 3D scanner collects 3D information about objects in the monitored area to facilitate the construction of a 3D model. The electronic display provides an image of the monitored area based on the 3D model. Furthermore, the electronic display provides visual highlighting of objects deemed too close to the vehicle (i.e., objects within a predetermined threshold distance from the vehicle).

According to some embodiments described herein, a 3D electronic display (one or both of monochrome and color) provides visual highlighting of an object. Furthermore, in various embodiments, the 3D electronic display can be configured to present images and related information in so-called "glasses-free" 3D or autostereoscopic 3D. Specifically, in some embodiments, the 3D electronic display can employ a diffraction grating-based, or "grating-based," backlight to produce different views of a 3D image or information. In a 3D electronic display employing a grating-based backlight, multiple diffraction gratings are used to couple light out of a light guide. The coupled-out light forms multiple light beams oriented in a predetermined direction (e.g., a viewing direction). Furthermore, in some embodiments, the light beams in the multiple light beams can have different principal angular directions from one another to form or provide a light field in the viewing direction of the electronic display, and can also represent multiple primary colors. Light beams having different principal angular directions (also referred to as "differently oriented light beams") (and in some embodiments, representing different colors) can be employed to autostereoscopically display information including three-dimensional (3D) information. For example, differently directed, differently colored light beams may be modulated and used as color pixels of, or to represent different views of, a "glasses-free" 3D color electronic display.

Here, a "lightguide" is defined as a structure that guides light within the structure using total internal reflection. Specifically, a lightguide may include a core that is substantially transparent at the operating wavelength of the lightguide. In various embodiments, the term "lightguide" generally refers to a dielectric light waveguide that uses total internal reflection at the interface between the dielectric material of the lightguide and the material or medium surrounding the lightguide to guide light. By definition, the condition for total internal reflection is that the refractive index of the lightguide is greater than the refractive index of the surrounding medium adjacent to the surface of the lightguide material. In some embodiments, the lightguide may include a coating in addition to or instead of the refractive index difference described above to further promote total internal reflection. For example, the coating may be a reflective coating. The lightguide may be any of several lightguides including, but not limited to, one or both of a plate or slab lightguide and a strip lightguide.

Furthermore, as in "plate lightguide," when applied to a lightguide, the term "plate" is defined as a piece-wise or differentially planar layer or sheet, and "plate lightguide" is sometimes referred to as a "sheet" lightguide. Specifically, a plate lightguide is defined as a lightguide configured to guide light in two substantially orthogonal directions bounded by a top surface and a bottom surface (i.e., opposing surfaces) of the lightguide. Furthermore, herein, by definition, the top surface and the bottom surface are both separate from each other and may be substantially parallel to each other in at least a differential sense. That is, within any differentially small portion of the plate lightguide, the top surface and the bottom surface are substantially parallel or coplanar.

In some embodiments, the plate light guide can be substantially flat (e.g., constrained to a plane) and thus be a planar light guide. In other embodiments, the plate light guide can be curved in one or two orthogonal dimensions. For example, the plate light guide can be curved in a single dimension to form a cylindrical plate light guide. However, any curvature has a sufficiently large radius of curvature to ensure that total internal reflection is maintained within the plate light guide to guide light.

In accordance with various embodiments described herein, a diffraction grating (e.g., a multibeam diffraction grating) can be employed to scatter or couple light as a beam out of a light guide (e.g., a plate light guide). Here, a "diffraction grating" is generally defined as a plurality of features (i.e., diffraction features) arranged to provide diffraction of light incident on the diffraction grating. In some embodiments, the plurality of features can be arranged in a periodic or quasi-periodic manner. For example, the diffraction grating can include a plurality of features arranged in a one-dimensional (1D) array (e.g., a plurality of grooves in a material surface). In other examples, the diffraction grating can be a two-dimensional (2D) array of features. For example, the diffraction grating can be a 2D array of bumps on the material surface or holes in the material surface.

Thus, according to the definitions herein, a "diffraction grating" is a structure that provides diffraction of light incident on the diffraction grating. If light is incident on the diffraction grating from a light guide, the diffraction or diffraction scattering provided can result in, and is therefore referred to as, "diffraction coupling", since the diffraction grating can couple light out of the light guide by diffraction. A diffraction grating also redirects or changes the angle of light by diffraction (i.e., at a diffraction angle). In particular, as a result of diffraction, the light exiting the diffraction grating (i.e., the diffracted light) typically has a propagation direction that is different from the propagation direction of the light incident on the diffraction grating (i.e., the incident light). Here, changing the propagation direction of light by diffraction is referred to as "diffraction redirection". Thus, a diffraction grating can be understood as a structure that includes diffraction features that diffractively redirect light incident on the diffraction grating, and if the light is incident from a light guide, the diffraction grating can also diffractively couple light out of the light guide.

Furthermore, as defined herein, the features of a diffraction grating are referred to as "diffractive features" and can be one or more of at a surface, in a surface, and on a surface (i.e., where "surface" refers to a boundary between two materials). The surface can be a surface of a plate light guide. The diffractive features can include any of a variety of structures that diffract light, including but not limited to one or more of grooves, ridges, holes, and protrusions, and these structures can be one or more of at a surface, in a surface, and on a surface. For example, a diffraction grating can include a plurality of parallel grooves in a material surface. In another example, a diffraction grating can include a plurality of parallel ridges protruding from a material surface. The diffractive features (whether grooves, ridges, holes, protrusions, etc.) can have any of a variety of cross-sectional shapes or profiles that provide diffraction, including but not limited to one or more of a sinusoidal profile, a rectangular profile (e.g., a binary diffraction grating), a triangular profile, and a sawtooth profile (e.g., a blazed grating).

As defined herein, a "multibeam diffraction grating" is a diffraction grating that produces outcoupled light comprising multiple light beams. Furthermore, as defined herein, the multiple light beams produced by the multibeam diffraction grating have different principal angular directions from one another. Specifically, as defined, one of the multiple light beams has a predetermined principal angular direction that is different from another of the multiple light beams due to diffraction coupling and diffraction redirection of incident light by the multibeam diffraction grating. The multiple light beams may represent a light field. For example, the multiple light beams may include eight light beams having eight different principal angular directions. For example, the combined eight light beams (i.e., the multiple light beams) may represent a light field. According to various embodiments, the different principal angular directions of the various light beams are determined by a combination of the grating pitch or spacing and the orientation or rotation of the diffraction features of the multibeam diffraction grating at the origin of each light beam relative to the propagation direction of light incident on the multibeam diffraction grating.

According to various embodiments described herein, light coupled out of a light guide through a diffraction grating (e.g., a multi-beam diffraction grating) represents pixels of an electronic display. Specifically, a light guide having a multi-beam diffraction grating to generate multiple light beams having different principal orientations can be part of a backlight for an electronic display or used in conjunction with an electronic display, such as, but not limited to, a "glasses-free" three-dimensional (3D) electronic display (also known as a multi-view or "holographic" electronic display or an autostereoscopic display). Thus, the differently oriented light beams generated by coupling the guided light out of the light guide using the multi-beam diffraction grating can be or represent "pixels" of the 3D electronic display.

Here, a "collimating" mirror is defined as a mirror having a curved shape that is configured to collimate light reflected by the collimating mirror. For example, the collimating mirror may have a reflective surface characterized by a parabolic curve or shape. In another example, the collimating mirror may include a shaped parabolic mirror. By "shaped parabola," it is meant that the curved reflective surface of the shaped parabolic mirror deviates from a "true" parabolic curve in a manner determined to achieve predetermined reflective characteristics (e.g., a degree of collimation). In some embodiments, the collimating mirror may be a continuous mirror (i.e., having a substantially smooth, continuous reflective surface), while in other embodiments, the mirror may include a Fresnel reflector or Fresnel reflector that provides light collimation. According to various embodiments, the amount of collimation provided by the collimating mirror may vary from one embodiment to another by a predetermined degree or amount. In addition, the collimating mirror may be configured to provide collimation in one or both of two orthogonal directions (e.g., a vertical direction and a horizontal direction). That is, according to various examples, the collimating mirror may include a parabolic or shaped parabolic shape in one or both of two orthogonal directions.

As used herein with respect to a 3D electronic display, the term "zero parallax plane" is defined as a plane or portion of a plane of a displayed or rendered 3D scene or region that appears the same (i.e., has no visual parallax) in all views of the 3D electronic display. Furthermore, as defined herein, the zero parallax plane occurs at, corresponds to, or coincides with the physical surface of the 3D electronic display. That is, when rendered by and viewed on the 3D electronic display, objects within the displayed scene or region located at the zero parallax plane within the 3D region will appear to be co-located with the physical surface of the 3D electronic display. Objects farther away than the zero parallax plane will appear to be behind the physical surface, while objects closer than the zero parallax plane will appear to be in front of the physical surface.

Here, a "projective transformation" or equivalently a "projective conversion" is defined as a (possibly non-linear) transformation of 3D space that maps lines to lines (or maps rays to rays). Note that a projective transformation can generally be represented by a 4×4 matrix according to a linear transformation in four-dimensional (4D) space (i.e., "projective space"). In some embodiments herein, the projective transformation may include an optical transformation configured to compress depth content that is substantially equivalent to viewing a scene through a diverging lens (e.g., a fisheye lens). Specifically, the projective transformation may map an infinite plane to a desired distance l/h from the zero parallax plane. The projective transformation that provides a mapping of an infinite plane to a distance l/h may be given by Equation (1)

Wherein, (x', y', z', w') are image coordinates corresponding to the projective transformation of the coordinates (x, y, z, w). In addition, according to the definition herein, the projective transformation of equation (1) generally does not compress the depth or disparity near the zero disparity plane itself. In other embodiments, another optical transformation (e.g., represented by a 4×4 matrix) can be used as the projective transformation here. For example, according to some embodiments of the principles described herein, the projective transformation can be substantially any projective transformation that highlights the object or a portion thereof as described below. In addition, according to various embodiments, here, the projective transformation can include a linear transformation or a nonlinear transformation.

In addition, as used herein, the word 'a' is intended to have its ordinary meaning in the present patent technology, i.e., one or more. For example, "grating" refers to one or more gratings, and therefore, "the grating" refers to the one or more gratings here. In addition, any reference to "top", "bottom", "above", "below", "up", "down", "front", "back", "first", "second", "left" or "right" here is not intended to be limiting. Here, unless otherwise expressly stated, the term "about" when applied to a value generally means within the allowable range of the device used to generate the value, or can mean plus or minus 10%, or plus or minus 5%, or plus or minus 1%. In addition, the term "substantially" as used herein refers to a majority, or almost all or all, or an amount in the range of about 51% to about 100%. In addition, the examples here are intended to be illustrative only and are presented for discussion purposes and not for limitation.

According to some embodiments of the principles described herein, a vehicle monitoring system is provided. FIG1 shows a block diagram of a vehicle monitoring system 100 in an example of an embodiment consistent with the principles described herein. FIG2A shows a perspective view of an area 102 monitored using the vehicle monitoring system 100 of FIG1 in an example of an embodiment consistent with the principles described herein. FIG2B shows a side view of the monitored area 102 of FIG2A in an example of an embodiment consistent with the principles described herein. As defined herein, an "area" monitored by the vehicle monitoring system 100 is an area near, adjacent to, or around a vehicle (hereinafter "areas" may be collectively referred to as "adjacent areas"). According to various embodiments, the monitored area 102 may include one or more of the front of the vehicle, the rear of the vehicle, and the side of the vehicle.

For example, vehicle monitoring system 100 can be used to monitor area 102 behind the vehicle and thus function as a backup or rear-view monitoring system. Specifically, vehicle monitoring system 100 can be configured as a rear-view or backup auxiliary vehicle monitoring system to assist in collision avoidance when the vehicle is moving backward. In another example, monitored area 102 can be in front of the vehicle. Thus, for example, vehicle monitoring system 100 can function as a front-end collision avoidance system when the vehicle is moving forward.

As shown in FIG1 , a vehicle monitoring system 100 includes a three-dimensional (3D) scanner 110. The 3D scanner 110 is configured to scan an area 102 adjacent to the vehicle. The scans from the 3D scanner are then used to generate or provide a 3D model of the area 102. Specifically, the 3D model includes the spatial configuration of objects 104 located within the scanned area 102. The scanned area 102 adjacent to the vehicle may also be referred to herein as a "scanned" area 102, or equivalently, as an "imaged" area 102.

Generally, the 3D scanner 110 may include any of a variety of 3D scanning or imaging systems capable of determining distances to various objects 104 within the scanned area 102. According to some embodiments, the 3D scanner 110 includes multiple cameras offset from one another. For example, the distance from the 3D scanner 110 to an object 104 within the scanned area 102 may be determined using disparity estimates of separate images captured by different cameras of the multiple cameras. For example, the multiple cameras may include a binocular camera pair, and the distance to the object 104 may be determined using binocular disparity estimates within the scanned area 102. An image processor (not shown in Figures 1, 2A, and 2B) of the vehicle monitoring system 100 may perform the disparity estimation and, according to some embodiments, may also generate or otherwise provide a 3D model based on the distance to the object 104 determined using the disparity estimates. For example, the image processor may be part of the 3D scanner 110.

In another embodiment, the 3D scanner 110 includes a scannerless light detection and ranging (LIDAR) system, such as a time-of-flight camera, in which the distance is determined from the propagation time of light pulses reflected by objects in the scanned area 102. Specifically, the time-of-flight camera uses a laser or another similar light source to generate light pulses. The light pulses are then used to illuminate the scanned area 102. Any objects 104 within the scanned area 102 reflect the illumination light pulses back to the time-of-flight camera. The distance to the object 104 is determined based on the length of time, or "time of flight," required for the illumination light pulse to propagate to the object, reflect off the object, and then return to the time-of-flight camera's light sensor (e.g., a focal plane array). For example, the time-of-flight distance can be determined pixel by pixel using a time-of-flight camera to provide a 3D model of the scanned area 102.

In another embodiment, the 3D scanner 110 includes a distance sensor configured to measure distances to a plurality of points within the scanned area 102. For example, the plurality of points may include an object 104. In some embodiments including a distance sensor, the 3D scanner 110 may also include a camera configured to capture a corresponding two-dimensional (2D) image of the scanned area 102. The measured distances provided by the distance sensor may be used to generate one or both of a point cloud and an object mesh of the scanned area 102. The point cloud or object mesh may then be used directly as a 3D model or employed to generate a 3D model (e.g., in an image processor of the vehicle monitoring system 100). The 2D image captured by the camera may be used to render the 3D model. By "rendering," this means overlaying the 2D image on or combining it with the 3D model (e.g., when the 3D model is presented on a display). For example, a variety of distance sensors may be employed in this embodiment of the 3D scanner 110, including but not limited to acoustic distance sensors and optical (e.g., based on a scanning laser) distance sensors.

Specifically, the distance sensor of the 3D scanner 110 may include a laser configured to scan the area 102. Furthermore, the distance sensor may include an optical sensor configured to measure distances to a plurality of points using laser light reflected from one or more objects 104 in the scanned area 102. For example, the 3D scanner 110 may include an Intel 3D camera that combines a 2D camera, a second infrared camera, and an infrared laser projector. The 2D camera is configured to capture a 2D image of the scanned area 102, while the infrared laser projector and the second infrared camera work together as a distance sensor to collect distance information within the scanned area 102. Intel and are registered trademarks of Intel Corporation, Santa Clara, CA, USA.

The vehicle monitoring system 100 shown in FIG1 also includes an electronic display 120. The electronic display 120 is configured to display a portion of the area 102 using a 3D model. Furthermore, the electronic display 120 is configured to visually highlight objects 104′ within the displayed portion that are located less than a threshold distance from the vehicle (or equivalently, from the vehicle monitoring system 100). According to various embodiments, the visual highlighting is configured to enhance user perception of objects 104′ that are closer to the vehicle than the threshold distance. For example, the enhanced perception of the visually highlighted objects 104′ can facilitate collision avoidance between the objects 104′ and the vehicle. In FIG2A and 2B , the threshold distance, labeled d _T , is illustrated as the distance from the vehicle monitoring system 100 to a plane 106, which is illustrated as a dashed boundary that intersects (e.g., intersects) the objects 104′ within the monitored area 102.

FIG3A illustrates a displayed portion 108 of area 102 according to an example of an embodiment consistent with the principles described herein. Specifically, FIG3A illustrates various objects 104 in scanned area 102 as they may appear on a display screen of electronic display 120. For example, electronic display 120 may be a two-dimensional (2D) electronic display 120 (e.g., an LCD display), and displayed portion 108 of scanned area 102 may be displayed or presented as a 2D image on the 2D electronic display. Furthermore, as shown in FIG3A , no object 104 is visually highlighted.

According to some embodiments, objects 104' that are closer than a threshold distance can be visually highlighted on or by the electronic display 120 using a mask applied to the objects 104'. For example, a mask comprising crosshatching or a colored shading can be applied to the highlighted objects 104' or a portion thereof. Additionally, for example, the mask can include a color (e.g., yellow, red, etc.) configured to draw attention to the masked objects 104'. In some examples, the mask can be applied to any portion (e.g., any pixel) of the scanned area 102 that is determined to be at a distance from the vehicle that is less than the threshold distance.

FIG3B shows a visually highlighted object 104′ in the displayed portion 108 of FIG3A in an example of an embodiment consistent with the principles described herein. Specifically, FIG3B shows a displayed portion of the scanned area 102 including an object 104′ that is visually highlighted using a mask 210. As shown in FIG3B , the mask 210 includes cross-hatching that obscures or obscures above an object 104′ that is closer than a threshold distance. In this example, the entire object 104′ is substantially covered by the cross-hatched mask 210. In other examples (not shown), only a portion of the object 104′ that is actually closer than the threshold distance is covered by the mask 210 to provide visual prominence, while the remaining portion of the object 104′ may be substantially free of the mask 210 (i.e., not covered by the mask 210).

In another example, the visual highlight displayed on the electronic display 120 includes an outline around the boundary or perimeter of an object that is closer than a threshold distance. The outline may include a color that draws special attention to the object, such as, but not limited to, yellow, orange, or red. Furthermore, in some examples, an outline may be provided around any portion or portions of the area 102 that are determined to be less than a threshold distance from the vehicle. In some examples, the outline may be used in conjunction with a mask (e.g., to also outline the masked object).

In other examples, a warning icon may be displayed on the electronic display 120 to highlight an object determined to be at a distance less than a threshold distance from the vehicle. For example, the warning icon may be displayed superimposed on the object or, equivalently, superimposed on the portion of the scanned area 102 that is within the threshold distance. For example, the warning icon may be presented in an attention-getting color and may include, but is not limited to, a triangle, a circle, or a square. In some examples, the triangle, circle, or square may surround an exclamation point or another alphanumeric character to further draw attention to the warning icon. In some embodiments, the warning icon may be used in conjunction with one or both of a shield and an outline (e.g., the warning icon may be located within the shield or the outline).

FIG3C illustrates a visually highlighted object 104′ in displayed portion 108 of FIG3A , according to an example of another embodiment consistent with the principles described herein. Specifically, FIG3C illustrates a displayed portion of scanned area 102 including object 104′ that is visually highlighted using outline 220. Further illustrated in FIG3C is a warning icon 230. While warning icon 230 can generally be located anywhere in the displayed portion, in FIG3C , as an example, warning icon 230 is located within outline 220 and superimposed above object 104′.

Referring again to FIG. 1 , according to some embodiments, the electronic display 120 of the vehicle monitoring system 100 may include a 3D electronic display 120. In some of these embodiments, the threshold distance may correspond to a zero-disparity plane associated with a portion of the area 102 displayed on the 3D electronic display 120. Furthermore, according to some embodiments, the visually salient object 104′ may be an object that is perceived as being in front of the zero-disparity plane of the 3D electronic display 120. Specifically, when displayed or presented, the object 104′ located at a distance less than the threshold distance is presented on the 3D electronic display 120 in front of the zero-disparity plane. Thus, according to various embodiments, the object is perceived (e.g., by a viewer) as protruding or extending from or in front of the physical display surface of the 3D electronic display 120, visually salient to the object 104′.

FIG4 shows a perspective view of a 3D electronic display 120 depicting a visually salient object 104′, according to an example of another embodiment consistent with the principles described herein. Specifically, FIG4 shows a displayed portion 108 of a scanned area 102 including an object 104′ that is visually salient by being presented in front of a zero parallax plane. Object 104′ (e.g., a children's toy bicycle) appears on the 3D electronic display as protruding from or located in front of a physical surface 120′ of the 3D electronic display. Other objects 104 at a distance greater than a threshold distance appear behind the physical surface 120′ of the 3D electronic display, as shown in FIG4 .

In some embodiments, a projective transformation can be applied to the 3D model before the displayed portion is rendered on the 3D electronic display 120. Specifically, the vehicle monitoring system 100 can also include an image processor, such as described below with respect to FIG6. For example, the image processor can be part of the 3D electronic display 120. In other examples, the image processor is part of the 3D scanner 110, or can be another (e.g., separate) component of the vehicle monitoring system 100.

The image processor may be configured to apply a projective transformation to the 3D model before presenting the displayed portion on the 3D electronic display 120. According to various embodiments, the projective transformation is configured to increase the relative size of a visually salient object 104' compared to other objects 104 in the image at distances greater than a threshold distance corresponding to a zero disparity plane. As a result, not only does the visually salient object 104' appear in front of the physical display surface 120' of the 3D electronic display 120, but when presented on the 3D electronic display 120, the visually salient object 104' is spatially deformed or increased in size. The effect is as if the visually salient object 104' is enlarged, magnified, or visually expanded or extended relative to other objects displayed by the 3D electronic display 120. For example, the object 104' shown in FIG. 4 is spatially deformed by the application of the projective transformation. Thus, according to various embodiments, the perception of the visually salient object 104' is further enhanced by the size-distorted presentation resulting from the application of the projective transformation.

According to various embodiments, 3D electronic display 120 can be substantially any 3D electronic display. Specifically, in some embodiments, 3D electronic display 120 is a multibeam grating-based 3D electronic display 120 that includes a multibeam grating-based backlight and a light modulation layer. FIG5A illustrates a cross-sectional view of a 3D electronic display 120 having a multibeam grating-based backlight, according to an example of an embodiment consistent with the principles described herein. FIG5B illustrates a cross-sectional view of a 3D electronic display 120 having a multibeam grating-based backlight, according to an example of another embodiment consistent with the principles described herein. FIG5C illustrates a perspective view of a portion of a 3D electronic display 120 having a multibeam grating-based backlight, according to an example of an embodiment consistent with the principles described herein. For example, the portion of 3D electronic display 120 shown in FIG5C may represent the 3D electronic display 120 shown in either FIG5A or FIG5B. According to various embodiments, a 3D electronic display 120 having a multibeam grating-based backlight can provide an enhanced perception of visually salient objects, as described above.

According to various embodiments, the 3D electronic display 120 shown in Figures 5A-5C is configured to generate modulated "directional" light, i.e., light that includes light beams having different principal directions. For example, as shown in Figures 5A-5C, the 3D electronic display 120 can provide or generate multiple light beams, shown as arrows directed away from and away from the 3D electronic display 120 in different predetermined principal directions (e.g., as a light field). The multiple light beams can then be modulated to facilitate the display of information having 3D content, including, but not limited to, visually highlighted objects. In some embodiments, the modulated light beams having different predetermined principal directions form multiple pixels of the 3D electronic display 120. Furthermore, the 3D electronic display 120 is a so-called "glasses-free" 3D electronic display (e.g., a multi-view, "holographic," or autostereoscopic display), wherein the light beams correspond to pixels associated with different "views" of the 3D electronic display 120.

As shown in Figures 5A, 5B, and 5C, the multi-beam grating-based backlight of the 3D electronic display 120 includes a light guide 122. Specifically, according to some embodiments, the light guide 122 can be a plate light guide 122. The plate light guide 122 is configured to guide light from a light source (not shown in Figures 5A-5C) as guided light (shown as extended arrows propagating in the light guide 122 as further described below). For example, the plate light guide 122 can include a dielectric material configured as a light waveguide. The dielectric material can have a first refractive index that is greater than a second refractive index of a medium surrounding the dielectric light waveguide. For example, the difference in refractive index is configured to promote total internal reflection of the guided light according to one or more guided modes of the plate light guide 122.

In various embodiments, light from a light source is guided as a beam along the length of the plate light guide 122. Furthermore, the plate light guide 122 can be configured to guide light (i.e., a guided beam) at a non-zero propagation angle. For example, the guided beam can be guided at a non-zero propagation angle within the plate light guide 122 using total internal reflection. Specifically, the guided beam 104 propagates by reflecting or "bouncing" between the top and bottom surfaces of the plate light guide 112 at a non-zero propagation angle (e.g., as shown by the extended, angled arrows representing rays of the guided beam).

As defined herein, a "non-zero propagation angle" is an angle relative to a surface (e.g., a top surface or a bottom surface) of the plate light guide 122. In some examples, the non-zero propagation angle of the guided light beam can be between about ten (10) degrees and about fifty (50) degrees, or in some examples between about twenty (20) degrees and about forty (40) degrees, or between about twenty-five (25) degrees and about thirty-five (35) degrees. For example, the non-zero propagation angle can be about thirty (30) degrees. In other examples, the non-zero propagation angle can be about 20 degrees, or about 25 degrees, or about 35 degrees.

In some examples, light from a light source is introduced or coupled into plate light guide 122 at a non-zero propagation angle (e.g., approximately 30-35 degrees). For example, one or more of a lens, a mirror, or similar reflector (e.g., a tilted collimating reflector), and a prism (not shown) can facilitate coupling the light as a beam at the non-zero propagation angle into the input end of plate light guide 122. Once coupled into plate light guide 122, the guided beam propagates along plate light guide 122 in a direction generally away from the input end (e.g., as shown in Figures 5A-5B by the thick arrow pointing along the x-axis).

Furthermore, according to some examples, the guided light beam produced by coupling light into the plate light guide 122 can be a collimated light beam. Specifically, by "collimated light beam," it is meant that the light rays within the guided light beam are substantially parallel to one another within the guided light beam. According to the definition herein, light rays that diverge or are scattered from the collimated light beam of the guided light beam are not considered to be part of the collimated light beam. For example, collimation of the light used to produce the collimated guided light beam can be provided by a lens or a reflector (e.g., a tilted collimating reflector, etc.) used to couple the light into the plate light guide 122.

In some examples, the plate light guide 122 can be a slab or plate light waveguide comprising an extended, substantially planar sheet of optically transparent dielectric material. The substantially planar sheet of dielectric material is configured to guide the guided light beam using total internal reflection. According to various examples, the optically transparent material of the plate light guide 122 can include or be composed of any of a variety of dielectric materials, including, but not limited to, one or more of various types of glass (e.g., quartz glass, alkali-aluminosilicate glass, borosilicate glass, etc.) and substantially optically transparent plastics or polymers (e.g., polyethylene (methyl methacrylate) or "acrylic glass", polycarbonate, etc.). In some examples, the plate light guide 122 can also include a cladding (not shown) on at least a portion of a surface (e.g., one or both of the top and bottom surfaces) of the plate light guide 122. According to some examples, the cladding can be used to further promote total internal reflection.

In Figures 5A, 5B, and 5C, the illustrated multibeam grating-based backlight for the 3D electronic display 120 further includes an array of multibeam diffraction gratings 124. As shown in Figures 5A-5B, the multibeam diffraction gratings 124 are located on a surface (e.g., the top or front surface) of the plate light guide 122. In other examples (not shown), one or more multibeam diffraction gratings 124 may be located within the plate light guide 122. In other embodiments (not shown), one or more multibeam diffraction gratings 124 may be located at or on the bottom or rear surface (i.e., the surface opposite the surface shown having the multibeam diffraction gratings 124) of the plate light guide 122. When combined, the plate light guide 122 and the array of multibeam diffraction gratings 124 provide or function as the multibeam grating-based backlight for the 3D electronic display 120.

According to various embodiments, the array of multibeam diffraction gratings 124 is configured to scatter or diffractively couple out a portion of the guided light beam as a plurality of light beams having different principal angular directions corresponding to different views of the 3D electronic display 120. For example, a portion of the guided light beam can be diffractively coupled out by the multibeam diffraction grating 124 through a plate light guide surface (e.g., through a top surface of the plate light guide 122). Furthermore, the multibeam diffraction grating 124 is configured to diffractively couple out a portion of the guided light beam as an out-coupled light beam, and to diffractively redirect the out-coupled light beam away from the plate light guide surface as the plurality of light beams. As discussed above, each of the plurality of light beams has a different predetermined principal angular direction determined by the characteristics of the diffraction signature of the multibeam diffraction grating 124.

According to various embodiments, the array's multibeam diffraction grating 124 includes a plurality of diffraction features that provide diffraction. The provided diffraction is responsible for diffractively coupling a portion of the guided light beam out of the plate light guide 122. For example, the multibeam diffraction grating 124 may include one or both of grooves in the surface of the plate light guide 122 and ridges protruding from the surface of the plate light guide as diffraction features. The grooves and ridges may be arranged parallel to each other, and at least at some point along the diffraction features, the grooves and ridges are perpendicular to the propagation direction of the guided light beam coupled out by the multibeam diffraction grating 124.

In some examples, grooves or ridges can be etched, milled, or molded into the surface of the plate light guide. In this way, the material of the multibeam diffraction grating 124 can include the material of the plate light guide 122. As shown in FIG5A, for example, the multibeam diffraction grating 124 includes substantially parallel grooves that penetrate the surface of the plate light guide 122. In FIG5B, the multibeam diffraction grating 124 includes substantially parallel ridges that protrude from the surface of the plate light guide 122. In other examples (not shown), the multibeam diffraction grating 124 can be a film or layer applied or attached to the surface of the plate light guide.

In some embodiments, the multibeam diffraction grating 124 may be or include a chirped diffraction grating. By definition, a "chirped" diffraction grating is one that exhibits or has a diffraction spacing (i.e., diffraction pitch) that varies across the width or length of the chirped diffraction grating, as shown, for example, in Figures 5A-5C. Herein, the varying diffraction spacing is defined and referred to as "chirp." As a result of the chirp, a portion of the guided light beams that are diffractively coupled out of the plate light guide 122 exit or are emitted from the chirped diffraction grating as outcoupled light beams at different diffraction angles corresponding to different origins on the chirped diffraction grating of the multibeam diffraction grating 124. The chirped diffraction grating is responsible for the predetermined and different principal angular directions of the outcoupled light beams of the multiple light beams, due to the predefined chirp.

In some examples, the chirped diffraction grating of the multibeam diffraction grating 124 can have or exhibit a chirp whose diffraction spacing varies linearly with distance. Thus, by definition, the chirped diffraction grating is a "linearly chirped" diffraction grating. For example, Figures 5A-5C illustrate the multibeam diffraction grating 124 as a linearly chirped diffraction grating. Specifically, as shown, the diffraction features are closer together at the second end of the multibeam diffraction grating 124 than at the first end. Furthermore, by way of example and not limitation, the diffraction spacing of the diffraction features shown varies linearly from the first end to the second end.

In another example (not shown), the chirped diffraction grating of the multibeam diffraction grating 124 can exhibit a nonlinear chirp of the diffraction spacing. A variety of nonlinear chirps can be used to implement the multibeam diffraction grating 124, including but not limited to exponential chirp, logarithmic chirp, or chirp that varies in another substantially non-uniform or random but still monotonic manner. Non-monotonic chirps, such as, but not limited to, sinusoidal chirp or triangular or sawtooth chirp, can also be employed. Any combination of these types of chirps can also be used.

According to some embodiments, the multibeam diffraction grating 124 may include diffraction features that are either curved or chirped, or both. FIG5C illustrates a perspective view of a multibeam diffraction grating 124 that is both curved and chirped, located in, at, or on the surface of the plate light guide 122 (i.e., the multibeam diffraction grating 124 is a curved and chirped diffraction grating). In FIG5C , the guided light beams have incident directions relative to the multibeam diffraction grating 124, indicated by thick arrows at a first end of the multibeam diffraction grating 124. Also illustrated are multiple coupled-out or emitted light beams, indicated by arrows pointing away from the multibeam diffraction grating 124 at the surface of the plate light guide 122. As shown, the light beams are emitted in a plurality of predetermined different principal angular directions. Specifically, as shown, the predetermined different principal angular directions of the emitted light beams differ from one another in both azimuth and elevation. According to various examples, both the predefined chirp of the diffraction feature and the curve of the diffraction feature may be responsible for the predetermined different principal angular directions of the emitted light beams.

Specifically, at different points along the curve of the diffractive feature, the "underlying diffraction grating" of multibeam diffraction grating 124 associated with the curved diffractive feature has different azimuthal orientation angles _Φf . By "underlying diffraction grating," we mean the diffraction gratings of the plurality of uncurved diffraction gratings that are superimposed to produce the curved diffractive feature of multibeam diffraction grating 124. At a given point along the curved diffractive feature, the curve has a particular azimuthal orientation angle Φf that is generally different from the azimuthal orientation angle _Φf at another point along the curved diffractive feature. Furthermore, this particular azimuthal orientation angle _Φf results in a corresponding azimuthal component _Φ in the principal angle directions {θ, Φ} of the light beam emitted from the given point. In some examples, the curve of a diffractive feature (e.g., a groove, ridge, etc.) can represent a portion of a circle. The circle can be coplanar with the lightguide surface. In other examples, the curve can represent a portion of an ellipse or another curved shape, for example, coplanar with the lightguide surface.

5A-5B , the modulation layer of the 3D electronic display 120 includes a light valve array 126. According to various embodiments, the light valve array 126 is configured to modulate light beams of different orientations (i.e., a plurality of light beams having different predetermined principal directions) corresponding to different views of the 3D electronic display 120. Specifically, light beams of the plurality of light beams pass through and are modulated by respective light valves of the light valve array 126. According to various embodiments, the modulated light beams of different orientations may represent pixels of the 3D electronic display 120. In various examples, different types of light valves may be used in the light valve array 126, including but not limited to one or more of liquid crystal light valves, electrophoretic light valves, and electrowetting-based light valves.

According to some examples of the principles described herein, a three-dimensional (3D) vehicle monitoring system is provided. FIG6 shows a block diagram of a three-dimensional (3D) vehicle monitoring system 300 in an example of an embodiment according to the principles described herein. Specifically, the 3D vehicle monitoring system 300 can be configured to provide collision avoidance when the vehicle is moving in a monitored direction. For example, the 3D vehicle monitoring system 300 can be configured to monitor the area behind the vehicle and, accordingly, provide backup assistance to the operator of the vehicle.

As shown in FIG6 , the 3D vehicle monitoring system 300 includes a 3D camera 310. In some embodiments, the 3D camera 310 is a rear-facing 3D camera 310. The 3D camera 310 is configured to capture a 3D image of an area adjacent to the vehicle (e.g., behind the vehicle). According to various embodiments, the 3D camera 310 can be substantially similar to the 3D scanner 110 described above with respect to the vehicle monitoring system 100. Specifically, the 3D camera 310 can include one or more of the following: a plurality of cameras offset from one another, a time-of-flight camera, and a combination of a laser-based distance sensor and a two-dimensional (2D) camera configured to monitor an area adjacent to the vehicle.

The 3D vehicle monitoring system 300 shown in FIG6 further includes an image processor 320. The image processor 320 is configured to provide a 3D model of the 3D imaging area using the 3D images captured by the 3D camera 310. According to various embodiments, the 3D model includes the spatial configuration of objects within the 3D imaging area. The 3D imaging area and the objects within the 3D imaging area can be substantially similar to the area 102 and objects 104, 104' described above with respect to the vehicle monitoring system 100.

According to various embodiments, the 3D vehicle monitoring system 300 further includes a 3D electronic display 330. The 3D electronic display 330 is configured to display a portion of the 3D imaging area using a 3D model. According to some embodiments, any object within the displayed portion that is less than a threshold distance from the vehicle (e.g., from the rear of the vehicle) can be visually highlighted on the 3D electronic display 330. Specifically, according to some embodiments, the 3D electronic display 330 is further configured to visually highlight objects within the displayed portion that are less than a threshold distance from the vehicle.

In some embodiments, 3D electronic display 330 is substantially similar to 3D electronic display 120 of vehicle monitoring system 100 described above. For example, the threshold distance may correspond to a zero-parity plane associated with a portion of the 3D imaging area displayed by 3D electronic display 330. In some embodiments, visually highlighted objects may be perceived as being in front of the zero-parity plane (i.e., in front of the physical surface of 3D electronic display 330). Additionally, in some embodiments, image processor 320 is further configured to apply a projective transformation to the 3D model prior to presenting the displayed portion on 3D electronic display 330. The applied projective transformation may be configured to increase the relative size of the visually highlighted object compared to other objects in the displayed portion located at a distance greater than the threshold distance corresponding to the zero-parity plane.

In some embodiments, the 3D electronic display 330 may include a multibeam grating-based 3D electronic display. For example, in some embodiments, the 3D electronic display 330 may be substantially similar to the 3D electronic display 120 having a multibeam grating-based backlight and modulation layer described above with respect to the vehicle monitoring system 100. Specifically, the 3D electronic display 330 may include a multibeam grating-based backlight and a modulation layer. The multibeam grating-based backlight may include a light guide for guiding a light beam (e.g., a collimated light beam) and an array of multibeam diffraction gratings configured to diffractively couple out multiple portions of the guided light beam as multiple differently oriented light beams directed away from the light guide. The light guide and the multibeam diffraction gratings may be substantially similar to the plate light guide 122 and the multibeam diffraction grating 124 described above with respect to the vehicle monitoring system 100. Furthermore, the modulation layer may include an array of light valves to modulate the differently oriented light beams. According to various embodiments, the modulated, differently oriented light beams form multiple different views of the 3D electronic display 330. The light valve array can be substantially similar to the light valve array 126 described above with respect to the vehicle monitoring system 100. Specifically, the modulated, differently directed light beams have different predetermined principal angular directions that form a plurality of pixels associated with different "views" of the 3D electronic display 330.

According to some embodiments (not shown), the 3D electronic display 330 may further include a light source. The light source is configured to provide light that propagates in the light guide as a guided light beam. Specifically, according to some embodiments, the guided light is light from the light source that is coupled to the edge (or input end) of the light guide. For example, a lens, a collimating reflector, or a similar device (not shown) may facilitate coupling the light into the light guide at the input end or edge of the light guide. In various examples, the light source may include substantially any light source, including but not limited to a light emitting diode (LED). In some examples, the light source may include a light emitter configured to produce substantially monochromatic light having a narrowband spectrum represented by a specific color. Specifically, the color of the monochromatic light may be a primary color of a specific color space or color model (e.g., a red-green-blue (RGB) color model).

According to some examples of the principles described herein, a method for vehicle monitoring is provided. The method for vehicle monitoring can be used to monitor an area or region adjacent to a vehicle. For example, the area or region can include, but is not limited to, the area in front of, to the side of, and behind the vehicle.

FIG7 shows a flow chart of a method 400 for vehicle monitoring according to an example of an embodiment consistent with the principles described herein. As shown in FIG7 , the method 400 for vehicle monitoring includes capturing 410 a 3D scan of an area adjacent to a vehicle using a 3D scanner. According to various embodiments, the 3D scanner used in capturing 410 can be substantially similar to the 3D scanner 110 described above with respect to the vehicle monitoring system 100. For example, the 3D scanner can include one or more of: a plurality of cameras offset from one another (e.g., a pair of binocular cameras), a time-of-flight camera, and a combination of a laser-based distance sensor and a two-dimensional (2D) camera. In some examples, the 3D scanner can be substantially similar to the 3D camera 310 described above with respect to the 3D vehicle monitoring system 300.

The vehicle monitoring method 400 shown in FIG7 also includes generating a 3D model from the captured 3D scan. According to various embodiments, the 3D model includes the spatial configuration of objects within the scanned area. For example, the 3D model can be generated from the 3D scan using one or both of a point cloud and an object mesh generated by a 3D scanner.

According to various embodiments, vehicle monitoring method 400 further includes displaying 430 a portion of the scanned area using the 3D model. According to various embodiments, displaying 430 the portion of the scanned area includes visually highlighting objects within the displayed portion at a distance from the vehicle that is less than a threshold distance. In some embodiments, displaying 430 the portion of the scanned area may utilize an electronic display substantially similar to electronic display 120 of vehicle monitoring system 100 described above. Furthermore, visually highlighting the objects may be substantially similar to any of the forms of visual highlighting described above. For example, the objects may be visually highlighted using one or more of a mask, an outline, and a warning icon. In another example, displaying 430 the portion of the scanned area may include utilizing a 3D electronic display as described above with respect to 3D electronic display 330 of 3D vehicle monitoring system 300. Through the 3D electronic display, the visually highlighted objects appear to be in front of a zero parallax plane of the 3D electronic display corresponding to the threshold distance.

According to some embodiments, displaying 430 the portion of the scanned area using a 3D electronic display (e.g., a 3D electronic display having a multi-beam grating-based backlight) may further include directing light as a light beam at a non-zero propagation angle in a plate light guide. Displaying 430 the portion of the scanned area using the 3D electronic display may further include diffractively coupling out a portion of the guided light beam using an array of multi-beam diffraction gratings on the plate light guide. For example, diffractively coupling out a portion of the guided light beam may include generating a plurality of coupled-out light beams, the plurality of coupled-out light beams being directed away from the plate light guide in a plurality of different principal angle directions corresponding to different views of the 3D electronic display. Furthermore, displaying 430 the portion of the scanned area using the 3D electronic display may further include modulating the plurality of coupled-out light beams using a plurality of light valves, the modulated light beams representing pixels of the 3D electronic display.

Additionally, the vehicle monitoring method 400 may include applying a projective transformation to the 3D model before displaying 430 the portion of the scanned area on the 3D display. In some embodiments, the projective transformation may include depth compression of the displayed portion to increase the relative size of highlighted objects compared to objects in the image at distances greater than a threshold distance corresponding to a zero disparity plane.

Thus, examples of vehicle monitoring systems, 3D vehicle monitoring systems, and vehicle monitoring methods that visually highlight objects closer to a vehicle than a threshold distance have been described. It should be understood that the examples described above are merely illustrative of some of the many specific examples that demonstrate the principles described herein. Clearly, those skilled in the art can readily devise numerous other arrangements without departing from the scope of the appended claims.

Claims (18)

1. A vehicle monitoring system, comprising: A three-dimensional (3D) scanner is configured to scan an area adjacent to a vehicle, the scan being used to provide a 3D model containing a spatial configuration of objects located within the scanned area; and An electronic display is configured to display a portion of the scanned area using the 3D model, and to visually highlight objects within the displayed portion, the displayed portion being located at a distance less than a threshold from the vehicle. The visual highlighting is configured to enhance user perception of objects closer to the vehicle than the threshold distance. The electronic display includes a 3D electronic display, the threshold distance corresponds to a zero parallax plane associated with a portion of the scanned area displayed by the 3D electronic display, and the visual prominence of an object located less than the threshold distance from the vehicle is the visual perception of an object in front of the zero parallax plane on the 3D electronic display. 2. The vehicle monitoring system of claim 1, wherein the 3D scanner comprises a plurality of cameras offset from each other, the distance from the 3D scanner being determined by parallax estimation using individual images captured by different cameras of the plurality of cameras. 3. The vehicle monitoring system according to claim 1, wherein the 3D scanner includes a time-of-flight camera. 4. The vehicle monitoring system according to claim 1, wherein the 3D scanner comprises: A distance sensor is configured to measure the distance from a plurality of points within the scanned area to the distance sensor; and A camera is configured to capture two-dimensional (2D) images of the scanned area, and the measured distances are used to generate one or both of a point cloud and an object mesh to provide the 3D model, the 2D images being used to draw the 3D model. 5. The vehicle monitoring system according to claim 4, wherein the distance sensor comprises: A laser configured to scan the scanned area; and A light sensor is configured to measure the distance to the plurality of points using laser light reflected from an object in the scanned area. 6. The vehicle monitoring system of claim 1, wherein the visual highlighting of an object located at a distance less than a threshold from the vehicle within the displayed portion includes one or more of a mask applied to the displayed object, an outline around the displayed object, and an alarm icon indicating the displayed object via the electronic display. 7. The vehicle monitoring system of claim 1, further comprising an image processor configured to apply a projection transformation to the 3D model before the displayed portion is presented on the 3D electronic display, the projection transformation being configured to enhance the relative size of highlighted objects compared to objects located at a distance greater than a threshold distance corresponding to the zero parallax plane. 8. The vehicle monitoring system according to claim 1, wherein the 3D electronic display comprises: A plate-shaped light guide is configured to guide the light beam at a non-zero propagation angle; An array of multi-beam diffraction gratings, the array of multi-beam diffraction gratings being configured to diffract and couple guided light as multiple coupled beams with different principal angle directions corresponding to different views of the 3D electronic display; and An array of light valves is configured to modulate the plurality of coupled light beams corresponding to different views of the 3D electronic display, the modulated light beams representing pixels of the 3D electronic display. 9. The vehicle monitoring system according to claim 8, wherein the multi-beam diffraction grating comprises a linearly chirped diffraction grating, and wherein the diffraction features of the multi-beam diffraction grating include one or both of a curved groove in the surface of the plate-shaped light guide and a curved ridge in the surface of the plate-shaped light guide. 10. The vehicle monitoring system according to claim 1, wherein the 3D scanner is configured to scan the area behind the vehicle, the enhanced user perception is configured to assist in collision avoidance when the vehicle moves in the opposite direction, and the vehicle monitoring system is a rear-view, backup-assisted vehicle monitoring system. 11. A three-dimensional (3D) vehicle monitoring system, comprising: A 3D camera is configured to capture 3D images of the area adjacent to the vehicle; An image processor is configured to use the 3D image to provide a 3D model of a region imaged in 3D, the 3D model including a spatial arrangement of objects within the region imaged in 3D; and A 3D electronic display is configured to display a portion of the 3D-imaged area using the 3D model, and to visually highlight objects within the displayed portion, the displayed portion being located at a distance less than a threshold from the vehicle. The visually highlighted object is configured to provide collision avoidance as the vehicle moves in the direction of the adjacent area. The threshold distance corresponds to a zero parallax plane associated with a portion of the 3D-imaged area configured to be displayed by the 3D electronic display, wherein the visually highlighted object in the display portion is perceived in front of the zero parallax plane. 12. The 3D vehicle monitoring system of claim 11, wherein the 3D camera includes one or more of a plurality of cameras offset from each other, a time-of-flight camera, a laser-based distance sensor, and a two-dimensional (2D) camera. 13. The 3D vehicle monitoring system of claim 11, wherein a projection transformation is applied to the 3D model before the displayed portion is presented on the 3D electronic display, the projection transformation being configured to enhance the relative size of highlighted objects compared to objects in the displayed portion at a distance greater than a threshold distance corresponding to the zero parallax plane. 14. The 3D vehicle monitoring system according to claim 11, wherein the 3D electronic display includes a 3D electronic display based on a multibeam grating. 15. A vehicle monitoring method, the method comprising: Use a 3D scanner to capture a 3D scan of the area adjacent to the vehicle; A 3D model is generated from the captured 3D scan, the 3D model containing the spatial configuration of objects located within the scanned area; and The 3D model is used to display a portion of the scanned area. The display of a portion of the scanned area includes objects visually highlighted within the displayed portion at a distance less than a threshold from the vehicle. The visually highlighted objects are configured to enhance user perception of objects that are closer to the vehicle than the threshold distance. The display of a portion of the scanned area also includes the use of a 3D electronic display, wherein the visually highlighted object appears in front of the zero parallax plane of the 3D electronic display corresponding to the threshold distance. 16. The vehicle monitoring method of claim 15, wherein generating the 3D model includes applying a projection transformation to the 3D model before displaying a portion of the scanned area on the 3D electronic display. 17. The vehicle monitoring method of claim 16, wherein the projection transformation includes depth compression of the displayed portion to enhance the relative size of the visually highlighted object compared to an object in the scanned region at a distance greater than a threshold distance corresponding to the zero parallax plane. 18. The vehicle monitoring method of claim 15, wherein displaying a portion of the scanned area using the 3D electronic display comprises: In a plate optical guide, light is guided as a beam at a non-zero propagation angle; A portion of the guided beam is diffracted at the coupling point of an array of multi-beam diffraction gratings on the plate light guide, wherein the portion of the guided beam at the diffraction coupling point includes generating a plurality of coupled beams, the plurality of coupled beams being directed away from the plate light guide in a plurality of different principal angular directions corresponding to different views of the 3D electronic display; and The plurality of coupled light beams are modulated using multiple light valves, the modulated light beams representing pixels of the 3D electronic display to display the portion as a 3D image.