Patent Publication Number: US-2021190531-A1

Title: Ar navigation method and apparatus

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims priority to Chinese Patent Application No. 202010466019.0, filed on May 28, 2020, which is hereby incorporated by reference in its entirety. 
     TECHNICAL FIELD 
     The present application relates to the field of intelligent transportation technologies, and in particular, to an AR navigation method and apparatus. 
     BACKGROUND 
     Augment Reality (AR) navigation, also referred to as real scene navigation, is a method for realizing navigation by combining AR technologies with map information. A navigation device can display real road information on a navigation route through a display screen, so as to provide people with more visual, intuitive and safe navigation services. 
     In fusion of virtual navigation guidance and a real road scene, it is necessary to generate a guidance route for turning of a vehicle at which the vehicle makes a turning and to integrate the same into the real road scene. In prior art, the guidance route for turning can be generated based on a navigation route. Specifically, multiple shape points on the navigation route can be obtained from a navigation system of the vehicle, and these shape points can be used to fit the guidance route for turning of the vehicle. 
     SUMMARY 
     Embodiments of the present application provide an AR navigation method and apparatus. 
     A first aspect of the embodiments of the present application provides an AR navigation method, including: acquiring a calibration parameter of a camera installed on a vehicle; acquiring information of a maneuvering point that the vehicle is about to pass through on a navigation route and information of an actual location point of the vehicle, where the vehicle makes a turning at the maneuvering point, the information of the maneuvering point includes a coordinate of the maneuvering point and a navigation direction of the vehicle at the maneuvering point, and the information of the actual location point of the vehicle includes a coordinate of the actual location point and an actual traveling direction of the vehicle at the actual location point; in response to receiving a signal of the vehicle entering a turning status, determining a first turning guidance track of the vehicle according to information of a current actual location point of the vehicle and the information of the maneuvering point; and converting the first turning guidance track according to the calibration parameter of the camera, to obtain a second turning guidance track in a coordinate system of the camera corresponding to the first turning guidance track. 
     A second aspect of the embodiments of the present application provides an AR navigation apparatus, including: 
     a camera calibrating module, configured to acquire a calibration parameter of a camera installed on a vehicle; 
     a navigating module, configured to acquire information of a maneuvering point that the vehicle is about to pass through on the navigation route and information of an actual location point of the vehicle, wherein the vehicle makes a turning at the maneuvering point, the information of the maneuvering point includes a coordinate of the maneuvering point and a navigation direction of the vehicle at the maneuvering point, and the information of the actual location point of the vehicle includes a coordinate of the actual location point and an actual traveling direction of the vehicle at the actual location point; 
     a route determining module, configured to, in response to receiving a signal of the vehicle entering a turning status, determine a first turning guidance track of the vehicle according to information of a current actual location point of the vehicle and the information of the maneuvering point; and 
     an AR displaying module, configured to convert the first turning guidance track according to the calibration parameter of the camera, to obtain a second turning guidance track in a coordinate system of the camera corresponding to the first turning guidance track. 
     A third aspect of the embodiments of the present application provides an electronic device, including: at least one processor; and a memory which is in a communicational connection with the at least one processor in communication; where the memory stores instructions executable by the at least one processor, and the instructions are executed by the at least one processor to cause the at least one processor to perform the method according to the first aspect of the embodiments of the present application. 
     A non-transitory computer-readable storage medium storing computer instructions is provided, where the computer instructions causes a computer to perform the method according to the first aspect of the embodiments of the present application. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
       The drawings are used to better understand solutions, but do not limit the present application. In the drawings: 
         FIG. 1  is a schematic diagram of an application scenario architecture for the method according to an embodiment of the present application; 
         FIG. 2  is a schematic flowchart of an AR navigation method according to a first embodiment of the present application; 
         FIG. 3  is a schematic diagram for determining a turning guidance track; 
         FIG. 4  is a schematic diagram of an AR navigation display interface; 
         FIG. 5  is a schematic flowchart of an AR navigation method according to a second embodiment of the present application; 
         FIG. 6  is a structural diagram of an AR navigation apparatus according to a third embodiment of the present application; and 
         FIG. 7  is a block diagram of an electronic device for implementing an AR navigation method of an embodiment of the present application. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     The following describes exemplary embodiments of the present application in combination with the drawings, in which various details of the embodiments of the present application are included to facilitate understanding, and they shall be considered as merely exemplary. Therefore, those skilled in the art should realize that various changes and modifications can be made to the embodiments described herein without departing from the scope and spirit of the present application. Similarly, for the sake of clarity and conciseness, the description of well-known functions and structures is omitted in the following. 
     Embodiments of the present application provide an AR navigation method and apparatus, which can ensure that a determined turning guidance track is closer to an actual traveling track of the vehicle, thereby improving user experience. 
     One of the above embodiments of the present application provides the following advantages or beneficial effects: information of a maneuvering point that a vehicle is about to pass through on a navigation route and information of an actual location point of the vehicle is acquired, where the information of the maneuvering point includes a coordinate of the maneuvering point and a navigation direction of the vehicle at the maneuvering point, and the information of the actual location point of the vehicle includes a coordinate of the actual location point and an actual traveling direction of the vehicle at the actual location point. When the vehicle has entered the turning status, the turning guidance track of the vehicle can be determined according to the actual location point of the vehicle, the maneuvering point passed through during the turning, the actual traveling direction and the navigation direction of the vehicle, so as to ensure that the determined turning guidance track is closer to the actual traveling track of the vehicle, and the driver can make an accurate turning according to the turning guidance track, thereby improving the user experience. 
     The other effects of optional implementations will be explained in the following in combination with specific embodiments. 
     The present application provides an AR navigation method. Illustratively, as shown in  FIG. 1 ,  FIG. 1  is a schematic diagram of an application scenario architecture for the method according to an embodiment of the present application. 
     In an exemplary environment  100  of the application scenario architecture, some typical objects are schematically shown, including a road  120 , a vehicle  110  traveling on the road  120 , a Global Positioning System (GPS) server  130 , and a navigation server  140 . 
     The vehicle  110  may be any type of vehicles that can carry people and/or objects and move via a power system such as an engine, including but not limited to a car, a truck, a bus, an electric vehicle, a motorcycle, a motor home, a train, etc. One or more vehicles  110  in the environment  100  may be a vehicle with a certain capability of autonomous driving, and such vehicles are also referred to as unmanned vehicles. Of course, another one or more vehicles  110  in the environment  100  may also be vehicles without the autonomous driving capability. 
     Specifically, a navigation terminal in the vehicle  110  is responsible for communication with the GPS server  130  and the navigation server  140 , where the navigation terminal can communicate with the GPS server  130  and the navigation server  140  through wireless communication. 
     The navigation terminal may be a vehicle, or an on-board communication apparatus or an on-board terminal installed on the vehicle for assisting traveling of the vehicle, or a chip in the on-board communication apparatus or the on-board terminal. The on-board terminal can be mobile or fixed. 
     The navigation terminal may be built, as one or more parts or units, inside an on-board module, an on-board module set, an on-board component, an on-board chip or an on-board unit. The vehicle performs a method of an embodiment of the present application through the built-in on-board module, on-board module set, on-board component, on-board chip or on-board unit. 
     The navigation terminal can also be an external terminal, such as a mobile phone, a tablet computer and the like, where the external terminal can cooperate with an on-board terminal built in a vehicle to realize navigation and other functions. 
     The GPS server  130  is configured to provide the navigation terminal with GPS data. According to the GPS data, the navigation terminal locates a geographical position thereof and performs navigation. 
     The navigation server  140  is configured to plan a navigation route for the navigation terminal. When a user needs to perform navigation, the user inputs a starting place and a destination through the navigation terminal, and the navigation terminal sends a path planning request to the navigation server  140 , where the path planning request includes the starting place and the destination. The navigation server  140  plans one or more road routes for the user according to the starting place and destination included in the path planning request, and sends a planned navigation route to the navigation terminal. After receiving the navigation route, the navigation terminal displays the navigation path on an electronic map through a display apparatus. 
     It should be understood that equipment and objects shown herein are only exemplary, and the objects that may appear in different traffic environments may change according to an actual situation. The scope of embodiments of the present application is not limited in this respect. 
     Therefore, when the vehicle  110  is an unmanned vehicle, the application scenario architecture further includes a control server (not shown in the figure). During participation of a traffic activity by the vehicle  110 , the control server acquires vehicle information required for control and management according to a preset period or in a temporary triggering manner, where the vehicle information includes a vehicle user (a user identifier, etc.), a driving mode (an autonomous driving mode/a semi-autonomous driving mode/a manual driving mode, etc.), a use mode (a private use mode/a rental mode, a dedicated mode/a shared mode, etc.), a right-of-way level (an emergency vehicle/a public vehicle/an ordinary vehicle, etc.), operating status (a position, a direction, a speed, an acceleration, an angular velocity, etc.), operating status (light setting, driver&#39;s operations, etc.), status of a component (a control component, a sensor component, a display component, etc.), external perception (information of other traffic participant, information of a traffic environment, etc.) and the like. The information is denoted by vehicle parameter identifiers, and the vehicle  110  actively informs the control server; or, after the control server requests the vehicle  110  and the vehicle  110  responds and feeds back to the control server, the information is stored in association with a temporary identifier of the vehicle  110 . 
     The AR navigation method according to the embodiments of the present application can be performed by a navigation terminal with an AR navigation function. Different from the prior art, in the AR navigation method according to the embodiments of the present application, during a turning of the vehicle, the navigation terminal determines a turning guidance track for the vehicle according to an actual location point of the vehicle, a maneuvering point passed through during the turning, an actual traveling direction and a navigation direction of the vehicle, so as to ensure that the determined turning guidance track is closer to an actual traveling track of the vehicle. 
     As shown in  FIG. 2 ,  FIG. 2  is a schematic flowchart of an AR navigation method according to a first embodiment of the present application. The method can specifically include: 
     S 101 : acquiring a calibration parameter of a camera installed on a vehicle. 
     During the AR navigation, a navigation route displayed on the display apparatus of the navigation terminal is a real road scene image, where the real road scene image is captured in real-time by the camera installed on the vehicle, and is the image of the road where the vehicle is located currently. The real road scene image includes a traffic light, a pedestrian, and buildings along both sides of the road, a plant and the like. 
     There may be one or more cameras, and the camera can be installed at a fixed position of the vehicle or can be moved. For example, the cameras are installed on both sides of the vehicle&#39;s head. The camera can also be replaced by other devices with a photography function, such as a video recorder, a camcorder, etc. 
     In the process of image measurement and vision application, an image captured by the camera is used to restore an object in a three-dimensional space. Assuming that there is a linear corresponding relationship between the image captured by the camera and the position of an object in the three-dimensional space: [image]=M(object), the process of solving the correspondence relationship M is referred to as camera calibration, where M is the calibration parameter of the camera. 
     A purpose of the camera calibration is to obtain internal and external parameters and a distortion parameter of the camera or camcorder. Accordingly, the calibration parameter of the camera includes the internal and external parameters and the distortion parameter of the camera. 
     Optionally, the external parameter of the camera includes three posture angles (a pitch angle, a yaw angle and a roller angle) of the camera and a height of the camera above the ground, etc. 
     The internal parameter of the camera may include a focal length, a center position of a lens, etc. 
     Existing calibration methods may be adopted for the camera calibration, including a traditional camcorder calibration method, an active vision camcorder calibration method or a camcorder self-calibration method, and the camcorder calibration method is not limited in the embodiments of the present application. 
     The process of the camcorder calibration can be performed after the navigation is turned on, so as to obtain the calibration parameter of the camera. The camera can also be calibrated before the navigation starts and stored in the navigation terminal. At this time, the navigation terminal simply needs to read the calibration parameter of the camera. 
     S 102 : acquiring information of a maneuvering point that the vehicle is about to pass through on the navigation route and information of an actual location point of the vehicle, where the vehicle makes a turning at the maneuvering point. 
     The information of the maneuvering point includes a coordinate of the maneuvering point and a navigation direction of the vehicle at the maneuvering point, and the information of the actual location point of the vehicle includes a coordinate of the actual location point and an actual traveling direction of the vehicle at the actual location point. 
     After the user turns on the navigation function, the navigation terminal receives GPS data from the GPS server, and obtains, according to the GPS data, the coordinate of the actual location point of the vehicle; and the actual traveling direction of the vehicle at the actual location point can be measured by a sensor on the vehicle. 
     After the user turns on the navigation function, a destination of the navigation is inputted by the user, and a starting place can be located or be inputted by the user. The navigation terminal generates a route planning request according to the starting place and the destination, sends the route planning request to the navigation server, and receives navigation route data returned from the navigation server. 
     The navigation route data includes information of a series of shape points on the navigation route and the information of the maneuvering point. The shape point is a point reflecting a shape of the route on the navigation route. The maneuvering point includes an intersection, a turning point, an entrance and an exit of an expressway, and a switching point between a main road and an auxiliary road, etc., where the intersection includes a cross-shaped intersection and a T-junction intersection. The navigation route consists of the shape point and the maneuvering point in order. 
     The information of the shape point includes a coordinate of the shape point, and the information of the maneuvering point includes a coordinate of the maneuvering point, a type of the maneuvering point, a navigation direction of the vehicle at the maneuvering point and a road name. The type of the maneuvering point may be a cross-shaped intersection, a T-junction intersection, an entrance and an exit of an expressway, and a switching point between a main road and an auxiliary road, etc. 
     In the process of the navigation, the navigation terminal determines a next maneuvering point that the vehicle will pass through according to the actual location point of the vehicle and the navigation route, and determines whether the vehicle makes a turning at the maneuvering point according to the information of the next maneuvering point and the navigation direction at the maneuvering point. If the vehicle makes a turning at the maneuvering point, the following steps of this embodiment will be performed; if the vehicle does not make a turning at the maneuvering point, a normal driving operation will be performed and the navigation terminal will normally display an entity image of the road. 
     S 103 : in response to receiving a signal of the vehicle entering a turning status, determining a first turning guidance track of the vehicle according to information of a current actual location point of the vehicle and the information of the maneuvering point. 
     In this embodiment, the navigation terminal detects whether the vehicle enters the turning status. In an exemplary manner, the user inputs an instruction indicating that the vehicle enters the turning status. After detecting the instruction inputted by the user, the navigation terminal determines, according to the instruction, that the vehicle enters the turning status. For example, the user can input “the vehicle enters a turning” or “turning” in a voice manner After detecting the voice input, the navigation terminal performs speech recognition, and determines, according to a result of the speech recognition, that the vehicle enters the turning status. 
     In another exemplary manner, the navigation terminal determines, according to a change of the traveling parameter of the vehicle, whether the vehicle enters the turning status. For example, determining whether the vehicle enters the turning status according to the actual traveling direction of the vehicle, the navigation direction of the vehicle, and a change between the actual location point and a positioning point corresponding to the actual location point of the vehicle. When the vehicle enters the turning status, the signal of the vehicle entering the turning status is generated. 
     The positioning point in the embodiments of the present application refers to a displayed point corresponding to the actual location point of the vehicle on the navigation route, i.e., a mapping point of the actual location point of the vehicle displayed on an electronic map. 
     The information of the maneuvering point includes the coordinate of the maneuvering point and the navigation direction of the vehicle at the maneuvering point. The information of the actual location point of the vehicle includes the coordinate of the actual location point and the actual traveling direction of the vehicle at the actual location point. The navigation terminal determines the first turning guidance track of the vehicle according to the coordinate of the actual location point of the vehicle, the actual traveling direction of the vehicle, the coordinate of the maneuvering point and the navigation direction. 
     As an example, the first turning guidance track is determined according to the method shown in  FIG. 3 . Take a current actual location point P as an endpoint, and a ray is made along the actual traveling direction of the vehicle at the point P, the ray intersects with a line segment BC at a point D, where the line segment BC is formed by a maneuvering point B and a shape point C located behind the maneuvering point B on the navigation route, and a shape point A in  FIG. 3  is located ahead of the maneuvering point B on the navigation route. An angle bisector is made for PDC, a vertical line for PD is made through the point P, and the vertical line for PD intersects with the angle bisector for the PDC at a point O. An arc PE is made with the point O as a circle center and OP as a radius, where the arc PE is tangent to the line segment BC at a point E. A curve EC between the point C and the point E is obtained using a curve fitting method. The arc PE and the curve EC are connected to form the first turning guidance track PEC. 
     Optionally, the curve EC can be obtained by using a Bessel curve fitting method. The first turning guidance track PEC can be in the form of an arc, a parabola, a hyperbola, etc., which is not limited in this embodiment. 
     S 104 : converting the first turning guidance track according to the calibration parameter of the camera, to obtain a second turning guidance track in a coordinate system of the camera corresponding to the first turning guidance track. 
     Image processing relates to two coordinate systems: a camcorder coordinate system (a coordinate system of the camera) and a world coordinate system (world coordinate). The world coordinate system, also referred to as a measurement coordinate system, is a three-dimensional rectangular coordinate system, which can be used as a reference to describe a spatial position of the camcorder and a spatial position of the object to be measured. The position of the world coordinate system can be freely determined according to an actual situation. The camcorder coordinate system is also a three-dimensional rectangular coordinate system, where the origin is located at the center position of a lens, the x-axis and the y-axis are respectively parallel to both sides of a phase plane, the z-axis is an optical axis of the lens and is perpendicular to an image plane. The world coordinate system and the three-dimensional coordinate system can be converted between each other. 
     The first turning guidance track is a moving track in the world coordinate system, while the turning guidance track in a real road scene image finally displayed on the display apparatus of the navigation terminal is a moving track in the coordinate system of the camera. Therefore, it is necessary to convert the first turning guidance track from the world coordinate system to the coordinate system of the camera, to obtain the second turning guidance track. For specific conversion methods, reference may be made to existing technologies, which will not be repeated here. 
     S 105 : superimposing the second turning guidance track to a real road scene image captured by the camera for display. 
     The second turning guidance track is configured to represent a turning direction and a turning radius for the vehicle. Step S 105  is an optional step. For example, in an autonomous vehicle, the second turning guidance track may not be displayed, and the vehicle controls a turning of the vehicle according to the second turning guidance track. 
     The turning guidance track obtained by the above methods conforms to the current actual traveling track of the vehicle, and for different maneuvering points, adjusted turning guidance tracks fitting thereto can be obtained. When a user makes a turning according to the turning guidance track, an accurate turning is made and user experience is improved. 
     In the process of the AR navigation, an image displayed on the display apparatus of the navigation terminal is a real road scene image, which is captured in real-time by the camera on the vehicle. The navigation apparatus needs to superimpose or fuse the real road scene image captured by the camera with AR data, where the AR data includes the second turning guidance track, and the AR data further includes: a name of a road where the vehicle is currently located, a remaining distance to reach the destination, remaining time to reach the destination, etc. 
       FIG. 4  is a schematic diagram of an AR navigation display interface. As shown in  FIG. 4 , the turning guidance track is superimposed to the road real scene image for display, where the turning guidance track can not only be used to represent the turning direction of the vehicle, but also the turning radius for the vehicle. When a driver makes a turning according to the turning guidance track, an accurate turning is made and user experience is improved. However, in the prior art, the turning guidance track can only represent the turning direction, but cannot represent the turning radius for the vehicle, if the driver makes a turning according to the turning guidance track, the turning may be too large or too small, resulting in a failed turning, or affecting normal traveling of other vehicles. 
     In the AR navigation display interface shown in  FIG. 4 , the current status displaying a vehicle is superimposed to the real road scene image previously. The upper left arrow shown in  FIG. 4  indicates that the vehicle is in a turning status, and the name of the road where the vehicle is currently located, the remaining distance of 3.1 km to reach the destination, and the remaining time of 8 minutes to reach the destination are shown in the upper left portion of the display interface; a circular map thumbnail, for displaying the navigation route and the positioning point of the vehicle, is shown in the lower right corner of the display interface. 
     In this embodiment, the calibration parameter of the camera installed on the vehicle is acquired, and the information of the maneuvering point that the vehicle is about to pass through on the navigation route and the information of the actual location point of the vehicle are obtained, where the vehicle makes a turning at the maneuvering point. When the vehicle has entered the turning status, a first turning guidance track of the vehicle is determined according to the information of the current actual location point and the information of the maneuvering point. The first turning guidance track is converted according to the calibration parameter of the camera, to obtain a second turning guidance track in the coordinate system of the camera corresponding to the first turning guidance track, and then the second turning guidance track is superimposed to the real road scene image captured by the camera for display, where the second turning guidance track is configured to denote the turning direction and the turning radius for the vehicle. The turning guidance track of the vehicle can be determined according to the actual location point of the vehicle, the maneuvering point passed through during the turning, the actual traveling direction and the navigation direction of the vehicle, so as to ensure that the determined turning guidance track is closer to the actual traveling track of the vehicle, and the driver can make an accurate turning according to the turning guidance track, thereby improving the user experience. 
     On the basis of the first embodiment,  FIG. 5  is a schematic flowchart of an AR navigation method according to a second embodiment of the present application. As shown in  FIG. 5 , the method can specifically include: 
     S 201 : acquiring a calibration parameter of a camera installed on a vehicle; and 
     S 202 : acquiring information of a maneuvering point that the vehicle is about to pass through on a navigation route and information of an actual location point of the vehicle, where the vehicle makes a turning at the maneuvering point. 
     For specific implementations of steps S 201  and S 202 , reference may be made to the description related to steps S 101  and S 102  in the first embodiment, which will not be repeated here. 
     S 203 : determining, according to a coordinate of the maneuvering point and a coordinate of the actual location point of the vehicle, that the vehicle is about to enter a turning status at the maneuvering point. 
     Illustratively, an actual distance between the vehicle and the maneuvering point is determined according to the coordinate of the maneuvering point and the coordinate of the actual location point of the vehicle. It is judged that whether the actual distance between the vehicle and the maneuvering point is smaller than a preset distance threshold. When the actual distance between the vehicle and the maneuvering point is smaller than the preset distance threshold, it is determined that the vehicle is about to enter the turning status. When the actual distance between the vehicle and the maneuvering point is greater than or equal to the preset distance threshold, it is determined that the vehicle does not enter the turning status. 
     The distance threshold can be 60 m, 70 m, 80 m, etc., which is not limited in this embodiment. Taking the distance threshold of 80 m as an example, the navigation terminal starts to judge whether the actual distance between the vehicle and the maneuvering point is smaller than 80 m after passing through a previous maneuvering point ahead of the maneuvering point. When the actual distance between the vehicle and the maneuvering point is smaller than 80 m, it is determined that the vehicle is about to enter the turning status. It can be understood that the vehicle being about to enter the turning status refers to that the vehicle will enter the turning status immediately or enter the turning status after a very short period of time. 
     S 204 : determining that the vehicle has entered the turning status according to information of a current actual location point of the vehicle, information of a current positioning point corresponding to the current actual location point, information of multiple continuous historical positioning points ahead of the current positioning point and information of actual location points corresponding to the historical positioning points. 
     A positioning point is a point corresponding to the actual location point of the vehicle on the navigation route. Each actual location point of the vehicle corresponds to a unique positioning point on the navigation route. The information of the positioning point includes the coordinate of the positioning point and the navigation direction of the vehicle at the positioning point. The information of the actual location point includes the coordinate of the actual location point and the actual traveling direction of the vehicle at the actual location point. The coordinate of the vehicle at the actual location point is different from the coordinate of the positioning point corresponding to the actual location point, and the actual traveling direction of the vehicle at the actual location point is different from the navigation direction of the vehicle at the positioning point corresponding to the actual location point. 
     Illustratively, distances between each of the historical positioning points and the actual location point corresponding to each of the historical positioning points are determined according to coordinates of the multiple continuous historical positioning points and coordinates of the actual location points corresponding to the historical positioning points; and an included angle between the actual traveling direction of the vehicle at the current actual location point and the navigation direction of the vehicle at the positioning point corresponding to the current actual location point is determined. When the distances between each of the historical positioning points and the actual location point corresponding to each of the historical positioning points increase continuously and the included angle is greater than a preset angle, it is determined that the vehicle has entered the turning status. 
     When the vehicle drives in a straight line, the distance between the positioning point and the actual location point may be fixed or fluctuated within a small range, that is, the distance between the positioning point and the actual location point may increase for a moment, decrease for a moment and remain unchanged for a moment, while time for increase or decrease is very short. However, after the vehicle makes a turning, the distance between the positioning point and the actual location point will increase continuously. Therefore, whether the vehicle has entered the turning status can be determined according to this feature. 
     In addition, when the vehicle drives in a straight line, the included angle between the navigation direction and the actual traveling direction of the vehicle is usually very small or zero. However, during a turning, the navigation direction of the vehicle changes very small, while the actual traveling direction of the vehicle changes greatly, thereby resulting in the increase of the included angle formed therebetween. Therefore, the angle between the actual traveling direction and the navigation direction of the vehicle can be used to determine whether the vehicle enters the turning status. If the included angle is greater than a preset angle, it is determined that the vehicle has entered the turning status. The preset angle can be, for example, 10 degrees, 8 degrees, 9 degrees, 11 degrees, etc. 
     In this embodiment, it is first determined that the vehicle is about to enter the turning status. On the basis of determining that the vehicle is about to enter the turning status, whether the vehicle has entered the turning status is further determined, so as to ensure that the turning guidance track is determined immediately after the vehicle enters the turning status, thereby ensuring that the determined turning guidance path is timely and accurate. If a turning guidance route is determined too early (the vehicle has not entered the turning status yet) according to the information of the current actual location point of the vehicle and the information of the maneuvering point, since the information of the current actual location point is not accurate, the determined turning guidance route will greatly deviate from the actual driving route of the vehicle. If the turning guidance route is determined too late (i.e. the vehicle has entered the turning status for a period of time) according to the information of the current actual location point of the vehicle and the information of the maneuvering point, since the vehicle has started to make a turning, and the determined turning guidance route appears with delay, which cannot well guide the user to make a turning. 
     In addition, in this embodiment, whether the vehicle has entered the turning status can be determined according to the actual status of the vehicle, i.e., according to the actual position and the actual traveling direction of the vehicle, thus ensuring that the finally determined status is accurate. 
     S 205 : in response to receiving a signal of the vehicle entering a turning status, determining a first turning guidance track of the vehicle according to the information of the current actual location point of the vehicle and the information of the maneuvering point. 
     For specific implementations of step S 205 , reference may be made to the description related to step S 103  in the first embodiment, which will not be repeated here. 
     S 206 : sampling the first turning guidance track to obtain multiple sampling points. 
     S 207 : converting coordinate values of the multiple sampling points into coordinate values in the coordinate system of the camera according to the calibration parameter of the camera. 
     S 208 : drawing the second turning guidance track according to the coordinate values of the multiple sampling points in the coordinate system of the camera. 
     In this embodiment, the first turning guidance track is converted from the world coordinate system to the coordinate system of the camera through steps S 206  to S 208 . Selecting an appropriate number of sampling points can reduce the amount of calculation in the process of coordinate conversion, thus saving conversion time, and ensuring that the converted second turning guidance track will not be biased. 
     S 209 : superimposing the second turning guidance track to a real road scene image captured by the camera for display. 
     The second turning guidance track is configured to denote the turning direction and the turning radius of the vehicle. 
     In this embodiment, it is determined, according to the coordinate of the maneuvering point and the coordinate of the actual location point of the vehicle, that the vehicle is about to enter the turning status at the maneuvering point; and it is determined, according to the information of the current actual location point of the vehicle, the information of the current positioning point corresponding to the current actual location point, the information of the multiple continuous historical positioning points ahead of the current positioning point, and the information of the actual location points corresponding to the historical positioning points, that the vehicle has entered the turning status, where the positioning point is a point corresponding to the actual location point of the vehicle on the navigation route. According to the actual status of the vehicle, i.e., according to the actual location and the actual traveling direction of the vehicle, whether the vehicle has entered the turning status can be determined accurately, and the turning guidance track for the vehicle can be determined immediately after the vehicle enters the turning status, so that the turning guidance track is closer to the current traveling direction of the vehicle, thereby improving the user experience. 
       FIG. 6  is a structural diagram of an AR navigation apparatus according to a third embodiment of the present application, as shown in  FIG. 6 . The AR navigation apparatus  600  of this embodiment includes: 
     a camera calibrating module  601 , configured to acquire a calibration parameter of a camera installed on a vehicle; 
     a navigating module  602 , configured to acquire information of a maneuvering point that the vehicle is about to pass through on the navigation route and information of an actual location point of the vehicle, where the vehicle makes a turning at the maneuvering point, the information of the maneuvering point includes a coordinate of the maneuvering point and a navigation direction of the vehicle at the maneuvering point, and the information of the actual location point of the vehicle includes a coordinate of the actual location point and an actual traveling direction of the vehicle at the actual location point; 
     a route determining module  603 , configured to determine, in response to receiving a signal of the vehicle entering a turning status, a first turning guidance track of the vehicle according to information of a current actual location point of the vehicle and the information of the maneuvering point; and an AR displaying module  604 , configured to convert the first turning guidance track according to the calibration parameter of the camera, to obtain a second turning guidance track in a coordinate system of the camera corresponding to the first turning guidance track. 
     In a possible implementation, the AR displaying module  604  is further configured to superimpose the second turning guidance track to a real road scene image captured by the camera for display. 
     In one possible implementation, the route determining module  603  is specifically configured to: 
     take the current actual location point P as an endpoint to make a ray along the actual traveling direction of the vehicle at the point P, where the ray intersects with a line segment BC at a point D, the line segment BC is formed by the maneuvering point B and a shape point C located behind the maneuvering point B on the navigation route; 
     make an angle bisector for an angle PDC, and make a vertical line for PD through the point P, the vertical line for PD intersecting with the angle bisector for the angle PDC at a point O; and make an arc with the point O as a circle center and OP as a radius, the arc being tangent to the line segment BC at a point E; 
     obtain a curve between the point C and the point E by using a curve fitting method; and 
     connect the arc and the curve to form the first turning guidance track. 
     In one possible implementation, the AR displaying module  604  is specifically configured to: 
     sample the first turning guidance track to obtain multiple sampling points; 
     convert coordinate values of the multiple sampling points to coordinate values in the coordinate system of the camera according to the calibration parameter of the camera; and 
     draw the second turning guidance track according to the coordinate values of the multiple sampling points in the coordinate system of the camera. 
     In a possible implementation, the route determining module  603  is further configured to: 
     determine, according to the coordinate of the maneuvering point and the coordinate of the actual location point of the vehicle, that the vehicle is about to enter the turning status at the maneuvering point; and 
     determine, according to the information of the current actual location point of the vehicle, information of a current positioning point corresponding to the current actual location point, the information of the multiple continuous historical positioning points ahead of the current positioning point, and information of actual location points corresponding to the historical positioning points, that the vehicle has entered the turning status, where the positioning point is a point corresponding to the actual location point of the vehicle on the navigation route. 
     In a possible implementation, the route determining module  603  determines, according to the coordinate of the maneuvering point and the coordinate of the actual location point of the vehicle, that the vehicle is about to enter the turning status at the maneuvering point, includes: 
     determining an actual distance between the vehicle and the maneuvering point according to the coordinate of the maneuvering point and the coordinate of the actual location point of the vehicle; and 
     determining that the vehicle is about to enter the turning status under a condition that the actual distance between the vehicle and the maneuvering point is smaller than a preset distance threshold. 
     In a possible implementation mode, the route determining module  603  determines, according to the information of the current actual location point of the vehicle, the information of the current positioning point corresponding to the current actual location point, the information of the multiple continuous historical positioning points ahead of the current positioning point, and the information of the actual location points corresponding to the historical positioning points, that the vehicle has entered the turning status, includes: 
     determining, according to the coordinates of the multiple continuous historical positioning points and coordinates of the actual location point corresponding to the historical positioning points, distances between each of the historical positioning points and the actual location point corresponding to each of the historical positioning points; 
     determining an included angle between an actual traveling direction of the vehicle at the current actual location point and a navigation direction of the vehicle at the current positioning point corresponding to the current actual location point; and 
     determining that the vehicle has entered the turning status under a condition that the distances between each of the historical positioning points and the actual location point corresponding to each of the historical positioning points increase continuously, and the included angle is greater than the preset angle. 
     According to the AR navigation apparatus provided by this embodiment, information of a maneuvering point that a vehicle is about to pass through on a navigation route and information of an actual location point of the vehicle is acquired, where the information of the maneuvering point includes a coordinate of the maneuvering point and a navigation direction of the vehicle at the maneuvering point, and the information of the actual location point of the vehicle includes a coordinate of the actual location point and an actual traveling direction of the vehicle at the actual location point. In response to receiving a signal of the vehicle entering the turning status, the turning guidance track of the vehicle can be determined according to the actual location point of the vehicle, the maneuvering point passed through during the turning, the actual traveling direction and the navigation direction of the vehicle, so as to ensure that the determined turning guidance track is closer to the actual traveling track of the vehicle, and the driver can make an accurate turning according to the turning guidance track, thereby improving the user experience. 
     According to an embodiment of the present application, an electronic device and a readable storage medium are further provided. 
     As shown in  FIG. 7 , which is a block diagram of an electronic device for an AR navigation method according to an embodiment of the present application, the electronic device is intended to represent various forms of digital computers, such as a laptop computer, a desktop computer, a workstation, a personal digital assistant, a server, a blade server, a mainframe computer, and other suitable computers. The electronic device may also represent various forms of mobile devices, such as a personal digital processing, a cellular phone, a smart phone, a wearable device, and other similar computing devices. Components shown herein, connections and relationships thereof, as well as functions thereof are merely examples and are not intended to limit the present application implementation described and/or claimed herein. 
     As shown in  FIG. 7 , the electronic device includes: one or more processors  701 , memory  702 , and interfaces for connecting various components, including a high-speed interface and a low-speed interface. The various components are interconnected through different buses and can be installed on a common motherboard or be installed in other ways as required. The processor may process instructions executed within the electronic device, where the instructions include instructions stored in or on a memory to display graphical information of the GUI on an external input/output apparatus (such as, a display device coupled to an interface). In other embodiments, a plurality of processors and/or a plurality of buses may be used with a plurality of memories and a plurality of memories, if required. Similarly, a plurality of electronic devices can be connected, each of which provides some of the necessary operations (for example, functions as a server array, a set of blade servers, or a multiprocessor system). In  FIG. 7 , one processor  701  is taken as an example. 
     The memory  702  is a non-transitory computer-readable storage medium according to the present application. The memory stores instructions executable by at least one processor to cause the at least one processor to perform the AR navigation method according to the present application. The non-transitory computer-readable storage medium of the present application stores computer instructions, where computer instructions cause a computer to perform the AR navigation method according to the present application. 
     The memory  702 , as a non-transitory computer-readable storage medium, can be configured to store a non-transitory software program, a non-transitory computer executable program and module, such as a program instruction/module (e.g., the camera calibrating module  601 , the navigating module  602 , the route determining module  603  and the AR displaying module  604 , shown in  FIG. 6 ) corresponding to the AR navigation method in the embodiment of the present application. By running the non-transitory software program, instructions and modules stored in the memory  702 , the processor  701  performs various functional applications and data processing of the server, that is, realizes the AR navigation method in the above method embodiments. 
     The memory  702  may include a program storing area and a data storing area, where the program storing area may store an operating system and application programs required by at least one function; and the data storing area may store data created according to the use of the electronic device for the AR navigation method and the like. In addition, the memory  702  may include a high-speed random access memory, and may also include a non-transitory memory, such as at least one magnetic disk storage device, a flash memory device, or other non-transitory solid-state memory devices. In some embodiments, the memory  702  may optionally include memories provided remotely with respect to the processor  701 , and these remote memories may be connected via a network to an electronic device for the AR navigation method. Examples of the above-mentioned network may include, but are not limited to, the Internet, an intranet, a local area network, a mobile communication network and a combination thereof. 
     The electronic device for the AR navigation method may further include: an input apparatus  703  and an output apparatus  704 . The processor  701 , the memory  702 , the input apparatus  703  and the output apparatus  704  may be connected via a bus or other means, and an example of a connection via the bus is shown in  FIG. 7 . 
     The input apparatus  703  may receive input digital or personal information, and generate key signal input related to a user setting and functional control of the electronic device. The input apparatus, for example, is a touch screen, a keypad, a mouse, a trackpad, a touchpad, a pointer, one or more mouse buttons, a trackball, a joystick and other input apparatuses. The output apparatus  704  may include: a display device, an auxiliary lighting device (e.g., a light emitting diode (LED)), a tactile feedback device (e.g., a vibration motor) and the like. The display device may include, but is not limited to, a liquid crystal display (LCD), an LED display and a plasma display. In some embodiments, the display device may be a touch screen. 
     Various embodiments of the systems and technologies described herein may be implemented in a digital electronic circuit system, an integrated circuit system, a specialized ASIC (application specific integrated circuits), computer hardware, firmware, software, and/or a combination thereof. These various embodiments may include: being implemented in one or more computer programs, where the one or more computer programs may be executed and/or interpreted on a programmable system including at least one programmable processor, where the programmable processor may be a specialized or general-purpose programmable processor, which may receive data and instructions from a storage system, at least one input apparatus and at least one output apparatus and send the data and instructions to the storage system, the at least one input apparatus and the at least one output apparatus. 
     These computer programs (also referred to as programs, software, software applications, or codes) include machine instructions for programmable processors and can be implemented by using a high-level procedure and/or object-oriented programming language, and/or an assembly/machine language. As used herein, the terms “machine-readable medium” and “computer-readable medium” refer to any computer program product, apparatus, and/or device (e.g., a magnetic disk, an optical disk, a memory, a programmable logic device (PLD)) for providing a machine instruction and/or data to the programmable processor, and include a machine-readable medium that receives a machine instruction as a machine-readable signal. The term “machine-readable signal” refers to any signal used to provide a machine instruction and/or data to the programmable processor. 
     In order to provide interaction with a user, the systems and techniques described herein may be implemented on a computer, where the computer has: a display apparatus (e.g., a CRT (cathode ray tube) or an LCD (liquid crystal display) monitor) for displaying information to the user; and a keyboard and a pointing device (e.g., a mouse or a trackball), through which the user can provide input to a computer. Other types of devices may also be used to provide interaction with the user; for example, the feedback provided to the user may be any form of sensing feedback (such as, visual feedback, auditory feedback, or tactile feedback); and the input from the user may be received in any form (including acoustic input, voice input, or tactile input). 
     The systems and technologies described here may be implemented in a computing system (e.g., a data server) including a back-end component, or in a computing system (e.g., an application server) including a middleware component, or in a computing system (e.g., a user computer having a graphical user interface or a web browser, through which the user can interact with the implementation of the systems and technologies described herein) including a front-end component, or in a computing system including any combination of the background component, the middleware component, or the front-end component. The components of the system may be interconnected via digital data communication (e.g., a communication network) in any form or medium. Examples of the communication network include: a local area network (LAN), a wide area network (WAN) and Internet. 
     The computing system may include a client and a server. The client and the server are generally located far away from each other and usually interact with each other through a communication network. A relationship between the client and the server is generated by computer programs running on corresponding computers and having a client-server relationship between each other. 
     It should be understood that steps can be reordered, added, or deleted by using the various forms of processes shown above. For example, the steps recited in the present application can be performed in parallel, in sequence or in different orders, as long as expected results of the technical solution disclosed by the present application can be realized, and there is no limitation herein. 
     The above specific implementations do not limit the protection scope of the present application. It should be understood by those skilled in the art that various modifications, combinations, sub-combinations and substitutions may be made according to design requirements and other factors. Any modification, equivalent replacement and improvement made within the spirit and principle of the present application shall be included in the protection scope of the present application.