KR20170068021A - Method for Generating Road Topology Information Based on Segment Modeling for High Definition Map - Google Patents

Abstract

In order to provide a high-precision map including GPS position information by storing and managing the number of GPS coordinates in a minimum memory, the present invention divides a road path into an appropriate number of segments based on segment modeling, The present invention relates to a method of generating shape information of a road in order to model a road surface with a predetermined function based on the number of GPS coordinate values, and to estimate and provide detailed GPS coordinate values.

Description

TECHNICAL FIELD [0001] The present invention relates to a method for generating a shape information of a road based on segment modeling for providing a high-

The present invention relates to a method of generating road shape information, and more particularly, to optimize the number of GPS (Global Positioning System) coordinates to provide a high-precision map including position information, To generate a road shape information.

Recently, various services such as a navigation service terminal, a location information service using map information on the Internet, and a control service for autonomous vehicle driving have been performed variously.

Such map information is provided on the basis of a database in which a road shape and GPS coordinate values for each position corresponding thereto are stored in units of a predetermined distance.

However, when the map information is managed only by the road shape information and the GPS coordinate value, there is a problem that a very large amount of memory must be used.

SUMMARY OF THE INVENTION Accordingly, the present invention has been made keeping in mind the above problems occurring in the prior art, and it is an object of the present invention to provide a method and apparatus for optimizing the number of GPS coordinates, Based on the shape information of the road by dividing the path of the road into an appropriate number of segments to model the road shape information with a predetermined function based on an appropriate number of GPS coordinate values and to estimate and provide detailed GPS coordinate values, And to provide a method of generating the same.

In order to do this, it is necessary to determine the number of segments of the road path and the number (degree) of the control points of the Bezier curve representing the segments by using an optimized method that minimizes the original data and the sense of heterogeneity And provides a method of generating shape information of a road that can solve the issue on the road.

According to another aspect of the present invention, there is provided a method of generating shape information of a road that can be performed in a processor of a computer system, And a first step of performing a Function A process on a path to be modeled among information on a shape of a road based on a road shape based on the coordinates of the road, And performing the Function A process for each of the paths separated by separating the path into two paths after performing the Function A process, and a second step of: Wherein, in accordance with whether or not the number of control points satisfies a predetermined condition according to a result of the second step, A third step of determining whether the number of trawl point whether determined by the number of end-point for the control path further comprises.

The road shape information generation method includes generating a corresponding Bezier curve according to the number of the final control points for the path and reducing the number of the GPS coordinate sample data stored in the map database, And to provide the coordinates to the application service.

The Function A process increases the number of initial control points by one and determines whether or not the error condition is satisfied up to a predetermined maximum number allowed and determines the largest number satisfying the error condition as the number of control points .

If the result of summing the number of control points of the result of the second step for each path separated by two passes is equal to or greater than the number of control points of the result of the first step in the third step, The number of control points of the path may be determined as the number of the final control points for the path.

According to the method of generating road shape information based on segment modeling according to the present invention, the path of a road can be divided into appropriate segments, and the number (degree, number of GPS coordinates) of control points of Bezier curves included in each segment is given It is possible to optimize to satisfy the lateral error and to make the starting and ending points of each segment coincide with the original data so that the connection of the front and rear segments is made smooth so that the original data and the sense of heterogeneity can be minimized.

Also, by optimizing the number of GPS coordinates and storing and managing them in a minimum amount of memory, it is possible to expect a lot of applications to a location information service and control service for autonomous vehicle driving by providing a high precision map including GPS position information.

1 is a diagram for explaining a modeling method using a general Bezier function.
2 is a diagram for explaining terms for a node, a path, a link, and a segment with respect to a shape of a road according to an embodiment of the present invention.
3 is a flowchart for explaining a conventional segment modeling method.
4 is a flowchart illustrating a method of generating shape information of a road based on segment modeling according to an embodiment of the present invention.
5 is a specific flowchart of Function A of FIG.
6 is a view for explaining an example of an apparatus for realizing a shape information generation method of a road based on segment modeling according to an embodiment of the present invention.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings. In the drawings, the same components are denoted by the same reference symbols as possible. In addition, detailed descriptions of known functions and / or configurations are omitted. The following description will focus on the parts necessary for understanding the operation according to various embodiments, and a description of elements that may obscure the gist of the description will be omitted. Also, some of the elements of the drawings may be exaggerated, omitted, or schematically illustrated. The size of each component does not entirely reflect the actual size, and therefore the contents described herein are not limited by the relative sizes or spacings of the components drawn in the respective drawings.

1 is a diagram for explaining a modeling method using a general Bezier function.

1, a Bezier curve for n + 1 (n is a natural number) sample data S with respect to the GPS coordinates on the (x, y) coordinate is expressed by the following equation (1) The sample data S is approximated to m + 1 (m is a natural number) control points C for the path (S-> C) so that the number of the corresponding control points (degree, number of GPS coordinates (T) < / RTI > Here, i = 0 ~ n, s i is the sample data (x, y) coordinates, l _i is s _i and s _{i - 1} spacing, c _i is a set of control points _{C = {c 0, c 1} , (distance between the arc length, each end of the curve) ..c _m} of the element, in case t s is the arc length.

[Equation 1]

Generally, the GPS operates at 100 Hz to acquire positional information, that is, GPS coordinates in units of 10 msec, so that the interval between sample data of GPS coordinates acquired in a vehicle traveling at 10 KPH (16.7 m / s) Can be approximated by a straight line of about 17 cm as in the case of l _i .

However, when modeling the sample data S into the Bezier curve B (t), the original sample data (GPS coordinates) and errors (e.g., MSE, Mean Square Error) may occur. This error increases as the arc length or the number of GPS coordinates forming the path increases, and the smaller the number of control points (degree), the larger the error. In the present invention, the number (order) of control points expressing each path is determined through optimized modeling as described below.

A Bezier curve is generated by dividing the path into a plurality of segments with respect to the sample data included in one path and by connecting the start point and end point of the Bezier curves of the preceding and succeeding segments to match the original data, Bezier curves can be connected smoothly and the original data and heterogeneity can be minimized. In other words, the same conditions as in the expression (2) can be used.

&Quot; (2) "

Accordingly, the Bezier curve B (t) of Equation (1) can be expressed as Equation (3).

&Quot; (3) "

The error MSE E (C ^* ) between the original sample data S = {s ₀ , s ₁ , ... s _n } and the corresponding Bezier curve B (t) can be expressed as shown in Equation (4).

&Quot; (4) "

This error control point to minimize the MSE E (C ^*) are C _k can be obtained by using a differential equation such as Equation 5]. A quintic Hermite Curve (QHC) can be inserted to ensure first- and second-order differential continuity between segments.

&Quot; (5) "

Equation (5) can be expressed in a matrix form as in Equation (6) (t _r is rth t).

&Quot; (6) "

The control points of the Bezier curve to be finally obtained can be obtained by the same operation as in Equation (7).

&Quot; (7) "

2 is a diagram for explaining terms for a node, a path, a link, and a segment with respect to a shape of a road according to an embodiment of the present invention.

A high precision map including GPS position information stored and managed in a memory or a database is used for a road information in addition to a facility or a background as shown in FIG. (Intersections, junctions / junctions by cars, etc.), and links connecting the nodes. A link is divided into a lane-based path, and a path is represented by segments containing road shape information.

In this case, the condition for dividing the path into segments is that the error between the original data (reference path) of each sample data in the segment and the Bezier curve, that is, the lateral error, according depends on whether they are within the reference error E _{lat .max} range.

&Quot; (8) "

To this end, in the present invention, a number of segments of a road path and a number (order) of control points of a Bezier curve expressing a segment are reduced by using a technique optimized to minimize the sense of heterogeneity The present invention relates to a method for generating shape information of a road, Therefore, in order to optimize the number of GPS coordinates in a variety of fields such as location information service and control service for autonomous vehicle driving, a high precision map including GPS position information is stored and managed in a minimum memory.

3 is a flowchart for explaining a conventional segment modeling method. As shown in FIG. 3, conventionally, in order to express a curve for a path by using a polynomial, the number of segments is fixed so as not to be flexible with respect to the degree, and the number of segments is changed to determine the number of segments .

Referring to FIG. 3, when an arbitrary path of a road shape is selected, a predetermined lateral error condition (for example, 100) is set for each segment while increasing the number of segment segments by a predetermined unit number (N _units ) , And determine the approximate number of segments N _segment (e.g., 1000) (S110 to S112). Thereafter, the number of segments determined as described above is reduced by the number of units (N _unit ) * (Step) from the number (initial step = 1/2) (S120), and whether or not the lateral error condition as described above is satisfied (S121, S122 ), The process is repeated (the number of segments is increased) by decreasing the value by 1/2 by Step until the step becomes the predetermined minimum value S _min (S130 to S132) By repeating the above process (decreasing the number of segments) by decrementing the value by 1/2 by S 1 _min and decrementing the sign by +1 (S140 to S141), by storing the number of segments N _segments in step S130, The segments are finally determined (S150).

However, in the present invention, a method of generating a flexible curve according to a degree of variation by modeling using a Bezier curve is used. At this time, the length of a segment is fixed and a curve (number of control points) As shown in Fig. The ultimate goal of creating a precise map database is to reduce the amount of data by transforming vast amounts of data into an easy to use structure. Therefore, the present invention solves the problem of dividing a given path into a plurality of segments when dividing the segments into a plurality of segments, and the number of control points representing the segments. Even if the Bezier curve is flexible to the degree, the required amount of computation increases nonlinearly according to the degree, so even if the order is unconditionally high, it is not a benefit.

4 is a flowchart illustrating a method of generating shape information of a road based on segment modeling according to an embodiment of the present invention. 5 is a specific flowchart of Function A of FIG.

In order to generate the shape information of the road according to the present invention, a predetermined application program readable by a computer can be executed and can be performed as follows according to the menu of the executed application program.

Referring to FIG. 4, first, the user selects a modeling object path from the information about the shape of the road based on the map database including the above-mentioned nodes, links, paths, and the GPS coordinates (location information) Segment modeling can be started (S210). Information on the shape of the road can be displayed on a display device of a terminal such as a computer, and the user can select a modeling path from the road shapes.

When an arbitrary path among the road shapes is selected as described above, a Function A process for determining the number of control points (N _ctrl ) satisfying the lateral error condition for the path as shown in Equation (8) (S211).

5, in the Function A process, first, the control point number (N _ctrl) to reset to the minimum number n _min, and (S310), n _min to the GPS coordinates of the sample data s _i preceding approximated Bezier curve curve with respect to the B (t) is obtained (S320), and it is determined whether the lateral error condition is satisfied as in Equation (8) (S330). This process is repeated until the number of control points (N _ctrl ) is increased by 1 (S340) to the maximum permissible number n _min (S350). If there is no number of control points (N _ctrl ) satisfying the lateral error condition (N _ctrl ) satisfying the lateral error condition (Success), the corresponding value is output.

In FIG. 4, the Function A process is performed on the corresponding path, and if Fail is detected, the corresponding path is divided by 1/2, and each segment is set as a new path so that the Function A process is performed again for each segment (S212).

If by performing the process with respect to the Function A set pass Success, and stores the number of control points in the output with respect to the path of Success (P_parent) (N _ctrl) to Nparent (S213). Subsequently, the path P_parent which is success is divided by 1/2 (S214), and the Function A process is performed for each of the paths (segments) child1 and child2 (S215 and S216). In the case of Fail, the above process is repeated (S21, 217). In case of Success, the number of control points (N _child1 , N _child2 ) for each of the paths P_child1 and P_child2 is stored (S220, S221).

Accordingly, if Nparent stored in S213 is larger than the sum of N _child1 and N _child2 , the path P_parent is divided by 1/2 (S223), and the whole process is performed again (S224).

However, it is possible to determine the N _child1, N is the summation result of the one or more _child2 Nparent stored in S213, the control point number for the pass _{(P_parent) (N ctrl = Nparent} ) as the final output (S223). In this way, with respect to the path (P_parent) the final output generated the Bezier curve control point according to the number (N _ctrl = Nparent) can be used for the service. That is, for each pass on the road, a corresponding Bezier curve corresponding to the number of the final control points is generated, and the GPS coordinates on the road based on the Bezier curve are provided to the application service even if the number of GPS coordinate sample data stored in the map database is reduced .

6 is a view for explaining an example of an apparatus for realizing a shape information generation method of a road based on segment modeling according to an embodiment of the present invention. The method of generating shape information of a road based on segment modeling according to an embodiment of the present invention may be implemented by hardware, software, or a combination thereof. For example, the method may be executed in the computing system 1000, May be implemented so that the process can be performed.

The computing system 1000 includes at least one processor 1100, a memory 1300, a user interface input device 1400, a user interface output device 1500, a storage 1600, And an interface 1700. The processor 1100 may be a central processing unit (CPU) or a memory device 1300 and / or a semiconductor device that performs processing for instructions stored in the storage 1600. Memory 1300 and storage 1600 may include various types of volatile or non-volatile storage media. For example, the memory 1300 may include a ROM (Read Only Memory) 1310 and a RAM (Random Access Memory)

Thus, the steps of a method or algorithm described in connection with the embodiments disclosed herein may be embodied directly in hardware, in a software module executed by processor 1100, or in a combination of the two. The software module may reside in a storage medium (i.e., memory 1300 and / or storage 1600) such as a RAM memory, a flash memory, a ROM memory, an EPROM memory, an EEPROM memory, a register, a hard disk, a removable disk, You may. An exemplary storage medium is coupled to the processor 1100, which can read information from, and write information to, the storage medium. Alternatively, the storage medium may be integral to the processor 1100. [ The processor and the storage medium may reside within an application specific integrated circuit (ASIC). The ASIC may reside within the user terminal. Alternatively, the processor and the storage medium may reside as discrete components in a user terminal.

In addition, the above-described elements and functions of the method for generating road shape information based on segment modeling according to an embodiment of the present invention can be realized by hardware, software, or a combination thereof. Furthermore, the above-described elements, functions, and the like according to an exemplary embodiment of the present invention may be embodied as computer-readable codes on a computer- or processor-readable recording medium when executed by one or more computers or processors. It is possible to do. The processor-readable recording medium includes all kinds of recording apparatuses in which data that can be read by the processor is stored. Examples of the recording medium readable by the processor include a ROM, a RAM, a CD-ROM, a magnetic tape, a floppy disk, an optical data storage device, and the like, and also a carrier wave such as transmission over the Internet. In addition, the processor readable recording medium may be distributed over networked computer systems so that code readable by the processor in a distributed manner can be stored and executed.

As described above, according to the method for generating shape information of a road based on segment modeling according to the present invention, the path of the road can be divided into appropriate segments, and the number of control points of the Bezier curve included in each segment The number of segments can be optimized to satisfy a given lateral error, and the start and end points of each segment can be matched with the original data to soften the connection of the front and back segments, have. Also, by optimizing the number of GPS coordinates and storing and managing them in a minimum amount of memory, it is possible to expect a lot of applications to a location information service and control service for autonomous vehicle driving by providing a high precision map including GPS position information.

As described above, the present invention has been described with reference to particular embodiments, such as specific elements, and specific embodiments and drawings. However, it should be understood that the present invention is not limited to the above- Those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the essential characteristics of the invention. Therefore, the spirit of the present invention should not be construed as being limited to the embodiments described, and all technical ideas which are equivalent to or equivalent to the claims of the present invention are included in the scope of the present invention .

Claims (4)

A method for generating shape information of a road performed by a processor of a computer system,
A first step of performing a Function A process for a modeling path among information on a shape of a road based on a map database including map information and GPS coordinates, wherein the Function A process comprises: Determining a number of control points satisfying an error condition between Bezier curves,
A second step of performing the Function A process for each of the paths separated by separating the path into two paths after performing the Function A process;
Whether or not the number of control points as a result of the first step is determined as the final number of control points for the path according to whether or not the number of control points as a result of the first step satisfies a predetermined condition according to a result of the second step The third step
Further comprising the steps of: The method according to claim 1,
To generate a corresponding Bezier curve according to the number of the final control points for the path and reduce the number of GPS coordinate sample data stored in the map database to provide GPS coordinates on the road based on the Bezier curve to the application service Wherein the road information includes at least one of road information and road information. The method according to claim 1,
In the Function A process,
Determining a maximum number satisfying the error condition as the number of control points by determining whether or not the error condition is satisfied up to a predetermined maximum number allowed by increasing the number of initial control points by 1 A method of generating shape information of a road. The method according to claim 1,
In the third step,
If the sum of the number of control points in the result of the second step for each path in which the paths are divided into two is greater than or equal to the number of control points in the result of the first step, And determining the number of the final control points for the path.

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