METHOD FOR ANALYZING SHAPE OF OBJECT AND DEVICE FOR TRACKING OBJECT WITH LIDAR

The present disclosure relates to a method of analyzing a shape of an object and a device for tracking an object with LiDAR. A method for analyzing a shape of an object by use of LiDAR, according to an embodiment of the present disclosure, comprises obtaining a plurality of layers of LiDAR points for the object by use of the LiDAR, determining a shape flag for each of the layers by use of at least a part of LiDAR points thereon according to a plurality of predetermined shape types, calculating a confidence score for the shape flag determined for each of the layers by use of the at least part of LiDAR points; and determining a shape flag of the object by use of the shape flags determined for the plurality of layers and the confidence scores.

CROSS-REFERENCE TO RELATED APPLICATION

The present application claims priority under 35 U.S.C. § 119(a) to Korean Patent Application No. 10-2022-0065238, filed on May 27, 2022, the entire contents of which is incorporated herein for all purposes by this reference.

BACKGROUND OF THE PRESENT DISCLOSURE

Field of the Present Disclosure

The present disclosure relates to a method of analyzing a shape of an object and a device for tracking an object with LiDAR.

Discussion of Related Art

Information about a target vehicle may be acquired using a Light Detection and Ranging (LiDAR) sensor(s), and an autonomous driving function of a vehicle (hereinafter referred to as a “host vehicle”) equipped with LiDAR may be assisted using the acquired information. However, when information about a target vehicle, which may be acquired by LiDAR, may be incorrect, the reliability of the host vehicle for autonomous driving may be deteriorated. Therefore, research for solving this problem may be underway.

In particular, when multiple-layered point data may be obtained for an object through LiDAR and the heading of the object may be determined from a layer selected through analyzing LiDAR points of each layer, if the selection of the layer is not appropriate, the reliability may also be greatly deteriorated.

The information included in this Background of the present disclosure section is only for enhancement of understanding of the general background of the present disclosure and may not be taken as an acknowledgement or any form of suggestion that this information forms the prior art already known to a person skilled in the art.

BRIEF SUMMARY

Various embodiments of the present disclosure may be directed to providing a method for analyzing a shape of an object and a device for tracking an object using LiDAR, which may be capable of analyzing a shape of a moving object especially for determining the heading.

Technical embodiments of the present disclosure may not be limited to the foregoing embodiments, and other technical embodiments will be apparent to a person having ordinary skills in the art from the description.

A method for analyzing a shape of an object by use of LiDAR, according to an embodiment of the present disclosure, comprises obtaining a plurality of layers of LiDAR points for the object by use of the LiDAR, determining a shape flag for each of the layers by use of at least a part of LiDAR points thereon according to a plurality of predetermined shape types, calculating a confidence score for the shape flag determined for each of the layers by use of the at least part of LiDAR points; and determining a shape flag of the object by use of the shape flags determined for the plurality of layers and the confidence scores.

In at least one embodiment, the confidence score may be calculated differently according to the predetermined shape type which the determined shape flag belongs to.

In at least one embodiment, the at least part of LiDAR points includes outer points which include a first end point, a second end point, and a break point, and the confidence score may be calculated by use of the outer points.

In at least one embodiment, the plurality of predetermined shape types include a L-shape and a I-shape, and the shape flag for each of the layers may be determined by a length and/or a width of a smallest rectangular shape box encompassing the outer points, and the confidence score includes a first score for the L-shape and a second score for the I-shape, the second score calculated differently from the first score.

In at least one embodiment, the first score may be calculated by at least one of a first L-parameter which may be calculated from distance variances of the associated outer points to a first line segment and a second line segment, respectively, the first line segment formed by connecting the first end point and the break point and the second line segment formed by connecting the break point and the second end point, a second L-parameter which may be calculated according to whether the associated outer points may be located at a host-vehicle side with respect to the first and second line segments, respectively, a third L-parameter which may be calculated from angles between two neighboring segments, each segment formed by connecting two neighboring points of the outer points, a fourth L-parameter which may be calculated according to whether there exists at least one of the outer points in each inner side division area other than either outer side among division areas which may be formed by dividing each of the line segments with 3 or more perpendicular lines, and a fifth L-parameter which may be calculated according to a proportion of at least one of length, width, and area between the shape box and a cluster box which may be defined by the whole LiDAR points of the object.

In at least one embodiment, the first score may be calculated by summing the L-parameters multiplied by weights, respectively.

In at least one embodiment, the weight for the fifth L-parameter may be greatest, the weight for the first of fourth L-parameter next greatest, and the weight for the second or third L-parameter smallest.

In at least one embodiment, the second score may be calculated by at least one of a first I-parameter which may be calculated from a distance variance of the associated outer points to a longer one of a first line segment and a second line segment, the first line segment formed by connecting the first end point and the break point and the second line segment formed by connecting the break point and the second end point, and a second I-parameter which may be calculated from angles between two neighboring segments associated to the second line segment, each segment formed by connecting tow neighboring points of the outer points.

In at least one embodiment, the second score may be calculated by summing the I-parameters multiplied by weights, respectively.

In at least one embodiment, the weight for the first I-parameter may be greater than the one for the second I-parameter.

In at least one embodiment, the determination of the shape flag of the object may be according to a predetermined priority order for the plurality of predetermined shape types, and may be finally made with the scores taken into consideration.

In at least one embodiment, the plurality of predetermined shape types include a L-shape and a I-shape, and the L-shape may be prior to the I-shape according to the predetermined priority order.

In at least one embodiment, in case where at least one L-shape flag may be included in the plurality of layers, if at least one of a first condition of whether a number of I-shape flags may be greater that a number of L-shape flags for the plurality of layers and a second condition that a greatest score among L-shape flag scores may be below a first predetermined score and a greatest score among I-shape flag scores may be equal to or over a second predetermined score may be satisfied, then the shape flag of the object may be determined as the I-shape.

In at least one embodiment, if there may be no L-shape flag in the plurality of layers and at least one I-shape flag may be included, then the shape flag of the object may be determined as the I-shape.

In at least one embodiment, the plurality of predetermined shape types further include a sL-shape, and the I-shape may be prior to the sL-shape according to the predetermined priority order.

In at least one embodiment, in case where there exists neither I-shape nor L-shape in the plurality of layers and at least one sL-shape flag may be included, if a greatest score among sL-shape flag scores may be equal to or over a third predetermined score, then the shape flag of the object may be determined as the sL-shape.

In at least one embodiment, a heading of the object may be determined using the LiDAR points on a layer whose shape flag may be determined as the shape flag of the object.

An object tracking device according to an embodiment of the present disclosure comprises LiDAR configure to obtain first to Mth(M is an integer of 2 or greater) layers of LiDAR points for objects including a target object, a clustering unit configured to group neighboring and similar points of the LiDAR points into clusters, and a shape analysis unit configured to analyze a shape of the target object based on a clustered LiDAR points, wherein the shape analysis unit comprises a layer shape determination unit configured to determine a shape flag for each of the first to Mthlayers by use of at least a part of LiDAR points thereon according to a plurality of predetermined shape types, and calculate a confidence score for the shape flag determined for each layer by use of the at least part of LiDAR points, and a target shape determination unit configured to determine a shape flag of the object by use of the shape flags determined for the layers and the confidence scores.

According to an embodiment of the present disclosure, a shape of a target object and the heading may be obtained more precisely by use of LiDAR.

Exemplary embodiments described herein may include a vehicle comprising the object tracking device as described herein.

And also, the performance and reliability of an autonomous vehicle may be enhanced.

The methods and devices of the present disclosure have other features and advantages which will be apparent from or may be set forth in more detail in the accompanying drawings, which may be incorporated herein, and the following Detailed Description, which together serve to explain certain principles of the present disclosure.

It may be understood that the appended drawings may not be necessarily to scale, presenting a somewhat simplified representation of various features illustrative of the basic principles of the present disclosure. The specific design features of the present disclosure as included herein, including, for example, specific dimensions, orientations, locations, and shapes will be determined in part by the particularly intended application and use environment.

DETAILED DESCRIPTION

In case where identical elements may be included in various embodiments, they will be given the same reference numerals, and redundant description thereof will be omitted. In the following description, the terms “module” and “unit” for referring to elements may be assigned and used interchangeably in consideration of convenience of explanation, and thus, the terms per se do not necessarily have different meanings or functions.

Furthermore, in describing the exemplary embodiments, when it may be determined that a detailed description of related publicly known technology may obscure the gist of the exemplary embodiments, the detailed description thereof will be omitted. The accompanying drawings may be used to help easily explain various technical features and it should be understood that the exemplary embodiments presented herein may not be limited by the accompanying drawings. Accordingly, the present disclosure should be construed to extend to any alterations, equivalents and substitutes in addition to those which may be particularly set out in the accompanying drawings.

Although terms including ordinal numbers, such as “first”, “second”, etc., may be used herein to describe various elements, the elements may not be limited by these terms. These terms may be generally only used to distinguish one element from another.

When an element may be referred to as being “coupled” or “connected” to another element, the element may be directly coupled or connected to the other element. However, it should be understood that another element may be present therebetween. In contrast, when an element may be referred to as being “directly coupled” or “directly connected” to another element, it should be understood that there may be no other elements therebetween.

A singular expression includes the plural form unless the context clearly dictates otherwise.

In the exemplary embodiment, it should be understood that a term such as “include” or “have” may be intended to designate that the features, numbers, steps, operations, elements, parts, or combinations thereof described in the specification may be present, and does not preclude the possibility of addition or presence of one or more other features, numbers, steps, operations, elements, parts, or combinations thereof.

Furthermore, the term “unit” or “control unit” included in the names of a hybrid control unit (HCU), a motor control unit (MCU), etc. may be merely a widely used term for naming a controller configured for controlling a specific vehicle function, and does not mean a generic functional unit. For example, each controller may include a communication device that communicates with another controller or a sensor to control a function assigned thereto, a memory that stores an operating system, a logic command, input/output information, etc., and one or more processors that perform determination, calculation, decision, etc. necessary for controlling a function assigned thereto.

Hereinafter, a method200of analyzing a shape of an object and a device100for tracking an object by use of a LiDAR sensor according to embodiments will be described with reference to the accompanying drawings. The method200of analyzing a shape of an object and the device100for tracking an object using a LiDAR sensor will be described using the Cartesian coordinate system (x-axis, y-axis, z-axis) for convenience of description, but may also be described using other coordinate systems. In the Cartesian coordinate system, the x-axis, the y-axis, and the z-axis may be perpendicular to each other, but the embodiments may not be limited thereto. That is, the x-axis, the y-axis, and the z-axis may intersect each other obliquely.

FIG.1is a schematic block diagram of an object-tracking device100using a LiDAR sensor according to an exemplary embodiment.

The object-tracking device100shown inFIG.1may include a LiDAR sensor110, a preprocessing unit120, a clustering unit130, and a shape analysis unit140.

The LiDAR sensor110may be configured to acquire a point cloud related to a target object, and may be configured to output the acquired point cloud to the preprocessing unit120as LiDAR data. In this embodiment, the LiDAR sensor110may be suitable to obtain a plurality of layers of LiDAR data for the object, each layer responsible for LiDAR point data of the object at its corresponding position in a vertical axis.

The preprocessing unit120may be configured to preprocess the LiDAR data. To this end, the preprocessing unit120may be configured to perform calibration to match the coordinates between the LiDAR sensor110and a vehicle equipped with the LiDAR sensor110(hereinafter referred to as a “host vehicle”). That is, the preprocessing unit120may convert the LiDAR data into data suitable for the reference coordinate system in consideration of the positional angle at which the LiDAR sensor110may be mounted to the host vehicle. In addition, the preprocessing unit120may perform filtering to remove points having low intensity or reflectance using intensity or confidence information of the LiDAR data. In addition, the preprocessing unit120may remove data reflected from the host vehicle. That is, since there may be a region that may be shielded by the body of the host vehicle depending on the mounting position and the field of view of the LiDAR sensor110, the preprocessing unit120may remove data reflected from the body of the host vehicle using the reference coordinate system.

The clustering unit130may be configured to group the point cloud, which may be the LiDAR data composed of a plurality of points related to the object acquired using the LiDAR sensor110, into meaningful units according to a predetermined criterion. That is, the clustering unit130may be configured to cluster the point cloud using the result of the preprocessing by the preprocessing unit120, and may output the clustered LiDAR points to the shape analysis unit140.

The shape analysis unit140may be configured to analyze the shape of a target object using the clustered LiDAR points of the point cloud, and may output the result of the analysis through an output terminal OUT1.

FIG.2is a flowchart of a method200of analyzing the shape of an object using a LiDAR sensor according to an embodiment.

The shape analysis unit140shown inFIG.1may be configured to perform the shape analysis method200shown inFIG.2, but the embodiment may not be limited thereto. That is, according to another embodiment, the shape analysis method200shown inFIG.2may be performed by an object-tracking device configured differently from the object-tracking device100shown inFIG.1. That is, the method200shown inFIG.2may not be limited to any specific type of operation performed by the LiDAR sensor110, the presence or absence of the preprocessing unit110, any specific type of preprocessing performed by the preprocessing unit110, or any specific type of clustering performed by the clustering unit130in the device shown inFIG.1.

FIG.3is a block diagram of an embodiment140A of the shape analysis unit140shown inFIG.1.

Hereinafter, for better understanding, the object shape analysis method200according to the embodiment will be described as being performed by the shape analysis unit140A shown inFIG.3, but the embodiment is not limited thereto. That is, according to another embodiment, the object shape analysis method200according to the embodiment may also be performed by a shape analysis unit configured differently from the shape analysis unit140A shown inFIG.3.

The shape analysis unit140A shown inFIG.3may include a layer shape determination unit142and a target shape determination unit144.

The layer shape determination unit142may be configured to receive the clustered LiDAR points from the clustering unit130through an input terminal IN1, may be configured to determine the first to Mthshapes of first to Mthlayers related to a target object using the LiDAR points, and may be configured to output the determined shapes of the first to Mthlayers to the target shape determination unit144(step210). Here, “M” may be a positive integer of 2 or greater.

After step210, the target shape determination unit144may finally determine the shape of the target object by analyzing the 1stto Mthshapes according to a predetermined priority, and may output the determined shape of the target object through the output terminal OUT1(step220).

Hereinafter, embodiments of the object shape analysis method200shown inFIG.2, the layer shape determination unit142shown inFIG.3, and the target shape determination unit144shown inFIG.3will be described with reference to the accompanying drawings.

FIG.4is a flowchart of an embodiment210A of step210shown inFIG.2.

The layer shape determination unit142shown inFIG.3may perform the method210A shown inFIG.4. To this end, the layer shape determination unit142may include a determination preparation unit152and a flag assignment unit156. In addition, the layer shape determination unit142may further include a moving object analysis unit154. In addition, the layer shape determination unit142may further include a roof layer inspection unit158.

The shape of each of the M layers, i.e. the first to Mthlayers, related to one target object may be determined as follows.

After step310, among the LiDAR points included in the mthlayer, the break point that is located farthest from the line segment (or baseline) connecting the first end point and the second end point is searched for (step312).

FIG.5is a diagram exemplarily showing the LiDAR points included in the mthlayer.

For better understanding, step210A shown inFIG.4will be described with reference toFIG.5, but is not limited thereto.

The LiDAR points related to one target object may be divided into M layers, i.e. the first to Mthlayers, in a vertical direction (e.g. the z-axis direction).

After step310, among the LiDAR points included in the mthlayer (e.g. p1to p10shown inFIG.5), the break point B (p4) that is located farthest from the line segment EL connecting the first end point A (p1) and the second end point C (p10) is searched for (step312).

Thereafter, a first line segment L1connecting the first end point p1and the break point p4and a second line segment L2connecting the second end point p10and the break point p4are generated (step314).

Steps310to314described above may be performed by the determination preparation unit152shown inFIG.3.

After step314, the moving object analysis unit154may analyze the distribution pattern of the first and second LiDAR points in the mthlayer, and may determine whether to assign a break flag to the mthlayer as a shape flag using the result of the analysis (step316).

Here, the first LiDAR points may be LiDAR points (e.g. p2and p3) located near the first line segment L1, among the LiDAR points (e.g. p1to p10shown inFIG.5). The second LiDAR points may be LiDAR points (e.g. p5to p9shown inFIG.5) located near the second line segment L2, among the LiDAR points (e.g. p1to p10shown inFIG.5).

The break flag may be a flag indicating that the possibility that the target object displayed through the LiDAR points included in the mthlayer is a moving object is low. That is, when the degree to which the LiDAR points are dispersed in the mthlayer is large, there is a possibility that the target object is a static object rather than a moving object. Therefore, it is possible to check whether the target object is a moving object or a static object using the variance of the LiDAR points.

FIG.6is a flowchart of an embodiment316A of step316shown inFIG.4.

The moving object analysis unit154may perform step316A shown inFIG.6. To this end, the moving object analysis unit154may include, for example, a first variance calculation unit162, a second variance calculation unit164, and a variance comparison unit166.

For example, referring toFIGS.3and6, after step314, the first variance calculation unit162calculates a first average value A1of the first distances between the first line segment L1and the first LiDAR points, as expressed using Equation 1 below (step420).

Here, “n” represents the total number of first LiDAR points included in the mth layer, and “xi” represents the first distances. Referring toFIG.5, “xi” corresponds to the spacing distances between the respective first LiDAR points p2and p3and the first line segment L1in the x-axis direction.

After step420, the first variance calculation unit162calculates a first variance V1of the first distances xi using the first average value A1of the first distances xi, as expressed using Equation 2 below, and outputs the calculated first variance V1to the variance comparison unit166(step422).

After step422, the second variance calculation unit164calculates a second average value A2of the second distances yi between the second line segment L2and the second LiDAR points, as expressed using Equation 3 below (step424).

Here, “q” represents the total number of second LiDAR points included in the mthlayer, and “yi” represents the second distances. Referring toFIG.5, “yi” corresponds to the spacing distances between the respective second LiDAR points p5to p9and the second line segment L2in the y-axis direction.

After step424, the second variance calculation unit164calculates a second variance V2of the second distances yi using the second average value A2of the second distances yi, as expressed using Equation 4 below, and outputs the calculated second variance V2to the variance comparison unit166(step426).

After step426, the variance comparison unit166determines whether the first variance V1is greater than a first variance threshold value VE1(step428). If the first variance V1is greater than the first variance threshold value VE1, the variance comparison unit166determines whether the second variance V2is greater than a second variance threshold value VE2(step430). Upon determining that the second variance V2is greater than the second variance threshold value VE2, the variance comparison unit166may assign the break flag to the mthlayer, and the process may go to step220(step432). The first and second variance threshold values VE1and VE2may be the same as or different from each other. Further, each of the first and second variance threshold values VE1and VE2may be set in advance for each layer and stored, or may be set in advance to a constant value regardless of the layers.

However, when the first variance V1is not greater than the first variance threshold value VE1or when the second variance V2is not greater than the second variance threshold value VE2, the possibility that the mthlayer is a moving object rather than a static object is higher, and thus the process goes to step318. For example, the static object may be an object that does not move, such as a traffic light, a tree, a traffic sign, or a guardrail, and the moving object may be an object that is moving, such as a vehicle.

As described above, the variance comparison unit166compares the first variance V1and the second variance V2with the first variance threshold value VE1and the second variance threshold value VE2, respectively, and assigns a break flag to the mthlayer in response to the result of the comparison.

Alternatively, step316may be omitted from the object shape analysis method200using a LiDAR sensor according to the embodiment.

Meanwhile, when the break flag is not assigned to the mthlayer, the flag assignment unit156may assign a shape flag to the mthlayer using at least one of the first line segment, the second line segment, the first LiDAR points, or the second LiDAR points (steps318and320).

To this end, as shown inFIG.3, the flag assignment unit156may include a temporary flag assignment unit170and a final flag assignment unit180.

The temporary flag assignment unit170temporarily assigns an L-shaped flag or an I-shaped flag to the mthlayer as a shape flag in consideration of the size of the shape box of the mthlayer including the first and second line segments L1and L2in response to the result of the comparison by the variance comparison unit166. The shape box will be described later in detail with reference toFIG.14. That is, upon recognizing that the break flag has not been assigned to the mthlayer because the first variance V1is not greater than the first variance threshold value VE1and/or because the second variance V2is not greater than the second variance threshold value VE2as a result of the comparison by the variance comparison unit166, the temporary flag assignment unit170may temporarily assign an L-shaped flag or an I-shaped flag to the mthlayer as a shape flag in consideration of the size of the shape box of the mthlayer including the first and second line segments (step318).

FIG.7is a flowchart of an embodiment318A of step318shown inFIG.4.FIGS.8A and8Bare exemplary diagrams for helping understanding step318A shown inFIG.7.

For example, the temporary flag assignment unit170may temporarily assign an L-shaped flag or an I-shaped flag to the mthlayer using at least one of the length or the width of the shape box (e.g. SB shown inFIG.8B) of the mthlayer.

That is, when it is recognized that the break flag has not been assigned to the mthlayer, whether the width of the shape box of the mthlayer falls within a first threshold width range TWR1or a second threshold width range TWR2may be determined (step440).

If the width of the shape box of the mthlayer falls within the first threshold width range TWR1, the I-shaped flag is temporarily assigned to the mthlayer (step442). However, if the width of the shape box falls within the second threshold width range, the L-shaped flag is temporarily assigned to the mthlayer (step444).

When the first threshold width range TWR1has a range of the first minimum value MIN1to the first maximum value MAX1and the second threshold width range TWR2has a range of the second minimum value MIN2to the second maximum value MAX2, the second minimum value MIN2may be greater than or equal to the first maximum value MAX1. In this way, the shape flag may be assigned to the mthlayer using the width of the shape box SB, but the embodiment may not be limited thereto. That is, according to another embodiment, the shape flag may be temporarily assigned to the mthlayer using at least one of the width or the length of the shape box SB.

The device100according to the embodiment may track an object having a length of a predetermined value TL2or less. When the length of the shape box SB shown inFIG.8Bfalls within the range of TL1to TL2, if the width of the shape box SB falls within the first threshold width range TWR1, the I-shaped flag may be temporarily assigned to the mthlayer, and if the width of the shape box SB falls within the second threshold width range TWR2, the L-shaped flag may be temporarily assigned to the mthlayer.

In order to perform the method shown inFIG.7, as shown inFIG.3, the temporary flag assignment unit170may include first and second width comparison units172and174.

In conclusion, the temporary flag assignment unit170may temporarily assign the L-shaped flag or the I-shaped flag to the mthlayer using at least one of the length or the width of the shape box SB (step318A).

The first width comparison unit172may compare the width of the shape box SB with the first threshold width range TWR1, and may temporarily assign the L-shaped flag to the mthlayer in response to the result of the comparison. If the length of the shape box SB may be equal to or smaller than a predetermined length, the sL-shape flag may be temporally assigned. To this end, after determining the L-shape flag for the shape of the corresponding layer due to the comparison result that the width of the shape box SB may be within the first threshold width range TWR1, the first width comparison unit172may compare the length of the shape box SB with the predetermined length to determine whether to assign temporally the L-shape or the sL-shape flag to the layer. The second width comparison unit174, on the other hand, may compare the width of the shape box SB with the second threshold width range TWR2, and may temporarily assign the I-shaped flag to the mthlayer in response to the result of the comparison.

After step318, the final flag assignment unit180may determine whether to finally assign the L-shaped flag, the sL-shaped flag or the I-shaped flag, which has been temporarily assigned to the mthlayer, using at least one of the first line segment L1, the second line segment L2, the first LiDAR points, or the second LiDAR points (step320).

FIG.9is a flowchart of an embodiment320A of step320shown inFIG.4, andFIG.10is a diagram for helping understanding the embodiment320A shown inFIG.9. InFIG.10, it may be assumed that the first and second line segments L1and L2correspond to the first and second line segments L1and L2obtained in step314, respectively.

FIG.11is a flowchart of another embodiment320B of step320shown inFIG.4, andFIG.12is a diagram for helping understanding the embodiment320B shown inFIG.11.

FIGS.10and12represent an example of a case where the corresponding object may be located at the left upper side region (i.e., the second quadrant) from the host vehicle, and though the processes ofFIGS.9and11are detailed below therewith, they can be applied to objects located at other side region. Also, though the L-shape flag may be assumed inFIGS.9and11, the processes may be applied to the sL-shape flag too, and thus the details for the sL-shape flag may be omitted.

When the L-shaped flag was temporarily assigned to the mthlayer in step318, the shape flag may be finally assigned to the mthlayer through the method320A shown inFIG.9(step320A). However, when the I-shaped flag was temporarily assigned to the mthlayer in step318, the shape flag may be finally assigned to the mthlayer through the method320B shown inFIG.11(step320B).

In order to perform the embodiments320A and320B shown inFIGS.9and11, the final flag assignment unit180may include, for example, a reference line segment selection unit182, a first flag assignment analysis unit184, and a second flag assignment analysis unit186, as shown inFIG.3.

Upon recognizing that the L-shaped flag has been assigned to the mthlayer based on the result of the comparison by the first width comparison unit172, the first flag assignment analysis unit184may perform steps462to488shown inFIG.9. However, step462shown inFIG.9may be performed by the reference line segment selection unit182, rather than the first flag assignment analysis unit184.

After step318, the reference line segment selection unit182selects the longer line segment from among the first line segment L1and the second line segment L2, provided from the determination preparation unit152, as a reference line segment, and selects the shorter line segment from among the first line segment L1and the second line segment L2as a non-reference line segment (step460). For example, referring toFIG.10, since the second line segment L2may be longer than the first line segment L1, the first line segment L1may be selected as a non-reference line segment, and the second line segment L2may be selected as a reference line segment.

After step460, whether the length RL of the reference line segment (e.g. L2) may be greater than or equal to a threshold length TL is checked (step462). Here, the threshold length may be set differently for each of the M layers, or may be set identically.

If the length RL of the reference line segment is not greater than or equal to the threshold length TL, the shape flag is not assigned to the mthlayer (step488). However, when the length RL of the reference line segment is greater than or equal to the threshold length TL, the average and the variance of each of the reference line segment and the non-reference line segment are calculated (step464).

Here, the average of the reference line segment means an average of the distances between the reference line segment and the LiDAR points located near the reference line segment, and the variance of the reference line segment means a variance of the distances between the reference line segment and the LiDAR points located near the reference line segment. The average of the non-reference line segment means an average of the distances between the non-reference line segment and the LiDAR points located near the non-reference line segment, and the variance of the non-reference line segment means a variance of the distances between the non-reference line segment and the LiDAR points located near the non-reference line segment.

After step464, whether the average AARL and the variance AVRL of the reference line segment are less than a reference threshold average AARm and a reference threshold variance AVRm, respectively, is checked (step466). Here, each of the reference threshold average AARm and the reference threshold variance AVRm may be set in advance for each set of coordinates of the mthlayer and stored, or may be set in advance to a constant value regardless of the coordinates of the mthlayer and stored.

If the average AARL of the reference line segment is not less than the reference threshold average AARm, or if the variance AVRL of the reference line segment is not less than the reference threshold variance AVRm, the shape flag is not assigned to the mthlayer (step488).

However, if the average AARL of the reference line segment is less than the reference threshold average AARm and the variance AVRL of the reference line segment is less than the reference threshold variance AVRm, whether the average AANRL and variance AVNRL of the non-reference line segment are less than a non-reference threshold average AANRm and a non-reference threshold variance AVNRm, respectively, is checked (step468). Here, each of the non-reference threshold average AANRm and the non-reference threshold variance AVNRm may be set in advance for each set of coordinates of the mthlayer and stored, or may be set in advance to a constant value regardless of the coordinates of the mthlayer and stored.

If the average AANRL of the non-reference line segment is not less than the non-reference threshold average AANRm, or if the variance AVNRL of the non-reference line segment is not less than the non-reference threshold variance AVNRm, the shape flag is not assigned to the mthlayer (step488).

However, when the average AANRL of the non-reference line segment is less than the non-reference threshold average AANRm and the variance AVNRL of the non-reference line segment is less than the non-reference threshold variance AVNRm, the region related to the reference line segment is divided into i regions in the direction intersecting the reference line segment (step470). Here, “i” is a positive integer of 1 or greater, preferably 3 or greater. For example, “i” may be 4. For example, referring toFIG.10, it can be seen that the region related to the reference line segment L2is divided into four (i=4) regions AR1to AR4in the direction intersecting the reference line segment L2. In order to divide the region, three (i−1=3) straight lines may be arranged so as to be oriented in the direction intersecting the reference line segment L2.

After step470, whether a LiDAR point is present in each of the i regions resulting from the division is checked (step480). In other words, whether a LiDAR point are present in each of the four divided regions AR1to AR4is checked (step480). If no LiDAR point is present in even one of the four regions resulting from the division, the shape flag is not assigned to the mthlayer (step488).

However, when the LiDAR point is present in each of the regions resulting from the division, whether the spacing distance SD between neighboring outer LiDAR points located in the regions resulting from the division is less than a threshold spacing distance d is checked (step482). Here, the threshold spacing distance d may be set in advance. InFIG.10, a line segment can be defined by connecting two neighboring outer LiDAR points with a straight line. For example, a line segment connecting the outer points op1and op2, a line segment connecting the outer points op3and op4, a line segment connecting the outer points op4and op5, a line segment connecting the outer points op5and op6, and a line segment connecting the outer points op6and op7may be defined, and in step482, whether the length SDs of the segments is less than the threshold spacing distance d is determined. If the length SD of a segment is not less than the threshold spacing distance d, a shape flag is not assigned to the mthlayer (step488).

To determine the outer points, for example, ‘Convex hull’ algorithm may be used. According to the ‘Convex hull’ algorithm, if a point in-between two neighboring points is located at the nearer side to the host vehicle with respect to the line segment connecting the two neighboring points, then the point is extracted as an outer point of the object, and vice versa.

If the length SDs of the segments are less than the threshold spacing distance d, whether the angle θ12between the first line segment L1and the second line segment L2is greater than a first angle θ1and less than a second angle θ2is determined (step484). Here, the first angle θ1and the second angle θ2may be set in advance for each layer, or may be set in advance to a constant value regardless of the layers. If the angle θ12between the first line segment L1and the second line segment L2is less than the first angle θ1 or greater than the second angle θ2, the shape flag is not assigned to the mthlayer (step488).

However, if the angle θ12between the first line segment L1and the second line segment L2is greater than the first angle θ1and less than the second angle θ2, the L-shaped flag is finally assigned to the mthlayer (step486).

Upon recognizing that the I-shaped flag has been assigned to the mthlayer based on the result of the comparison by the second width comparison unit174, the second flag assignment analysis unit186may perform steps492to502shown inFIG.11.

First, referring toFIG.11, the longer line segment among the first line segment L1and the second line segment L2is selected as the reference line segment (step490). Since step490is the same as step460, a description thereof will be omitted.

After step490, whether the average ABRL and the variance BVRL of the reference line segment (L2shown inFIG.12) are less than a reference threshold average ABRm and a reference threshold variance BVRm, respectively, is determined (steps494and496). Here, the reference threshold average ABRm and the reference threshold variance BVRm may be the same as the reference threshold average AARm and the reference threshold variance AVRm shown inFIG.9, respectively, and may be set in advance for each of the M layers and stored, or may be set in advance to a constant value regardless of the layers and stored.

If the average ABRL is not less than the reference threshold average ABRm or if the variance BVRL is not less than the reference threshold variance BVRm, the shape flag is not assigned to the mthlayer (step502). However, if the average ABRL is less than the reference threshold average ABRm and the variance BVRL is less than the reference threshold variance BVRm, whether the spacing distance SDs between the outer points located in j regions resulting from the division in the direction intersecting the reference line segment are less than the threshold spacing distance d is determined (step498). Here, “j” is a positive integer of 1 or greater. “j” may be the same as or different from “i”. Since step498is the same as step482, a duplicate description thereof will be omitted.

If the spacing distance SD is not less than the threshold spacing distance d, the shape flag is not assigned to the mthlayer (step502). However, if the spacing distance SD is less than the threshold spacing distance d, the I-shaped flag is finally assigned to the mthlayer (step500).

Meanwhile, referring again toFIG.4, step210A may further include step322, which is performed after step320. That is, the layer shape determination unit142shown inFIG.3may further include a roof layer inspection unit158, which performs step322. In some embodiments, step322and the roof layer inspection unit158may be omitted.

After the flag is finally assigned to the mthlayer, a confidence score (hereinafter, referred to merely as ‘score’) is calculated according the type of the flag (step321).

To calculate the score, the layer shape determination unit142may further comprise a score calculation unit187comprising a first score calculation unit188and a second score calculation unit189.

At first, in case of L-shape or sL-shape flag, with reference toFIG.3, the first calculation unit188calculates a first score, and in case of I-shape flag, the calculation unit189calculates a second score.

The calculation of the first score is detailed with reference toFIG.10and the calculation of the second score with reference toFIG.12.

In the present embodiment, the first score may be calculated by applying weights for five parameters, but not limited thereto.

For the convenience sake, the above mentioned parameters may be referred to as L-parameters.

A first L-parameter LPS1relates to the distance variance of the outer points to the first line segment L1and the second line segment L2, and may be obtained by calculating the variances to the first line segment L1and the second line segment L2, respectively, and summing a first-line-segment score and a second-line-segment score accordingly obtained with reference to TABLE 1 below.

With reference to TABLE 1, if the calculated variance may be below a first predetermined variance value AV1, then 50 may be assigned to the score, if the variance equal to or over the AV1and below a second predetermined variance value AV2, then 20 assigned, and if the variance equal to or over the AV2, then 0 assigned. 1. variance to the first line segment L1or the second line segment L2.

For example, assuming that the distance variance of the outer points op1and op2to the first line segment L1may be below the first predetermined variance value AV1, and the distance variance of the outer points op3to op7to the second line segment L2may be equal to or over the first predetermined variance value AV1and below the second predetermined variance value AV2, 50 may be assigned to the first-line-segment score and 20 to the second-line-segment score, and thus the first L-parameter LPS1may be determined to have a score of 70.

Next, the second L-parameter LPS2relates to the locations of the outer points with respect to the first and second line segments, respectively, and may be determined according to the proportions of the points located at the nearer side to the host vehicle with respect to the first and second line segments, respectively.

In this embodiment, if the outer points associated to the first line segment L1may be all located at the host vehicle side with respect to the first line segment L1and the outer points associated to the second line segment L2may be all located at the host vehicle side with respect to the second line segment L2, then 100 may be assigned to the score, and otherwise 0.

For example, because the outer points op1and op2may be located at the host vehicle side with respect to the first line segment L1, and the outer points op3to op7may be located at the host vehicle side with respect to the second line segment L2, the score of the second L-parameter becomes 100.

Next, the third L-parameter relates to the average angle of minimum relative angles between neighboring segments.

With respect toFIG.10, the minimum relative angle between two neighboring segments may be defined as ‘180−the smaller angle between the segments,’ i.e. Θ s inFIG.10for the segment of points A and op1and the segment of points op1and op2, the smaller angle between two segments determined to be the smaller one among the two angles formed by two neighboring segments, and the third L-parameter LPS3may be obtained by assigning and summing scores for the respective first and second line segments, each score determined according to TABLE 2 by the average angle of the associated segments, the segments associated to the first line segment L1defined as the segments of A-op1, op1-op2, and op2-B, and the segments associated to the second line segment L2as the ones of B-op3, op3-op4, op4-op5, op5-op6, op6-op7, and op7-C.

With reference to TABLE 2, for the score for each line segment, if the average angle may be below a first predetermined angle Ang1, then 50 may be assigned, if the average angle equal to or over the first predetermined angle Ang1and below a second predetermined angle Ang2, then 25 assigned, and if the average angle over the second predetermined angle Ang2, then 0 assigned.

For example, assuming that the average angle between segments for the first line segment L1may be below the first predetermined angle Ang1and the average angle between segments for the second line segment L2may be equal to or over the first predetermined angle Ang1and below the second predetermined angle Ang2, 50 may be assigned to the first line segment score and 20 to the second line segment score, and thus the third L-parameter LPS3may be determined to have a score of 70.

Next, the fourth L-parameter LPS4relates to a straight line reliability, in more detail to whether the outer points may be evenly distributed. This parameter may be determined according to the presence of an outer point in each inner side division area other than either outer side among the division areas which may be formed by dividing each of the line segments with 3 or more perpendicular lines.

In the present embodiment, for at least one of the first line segment L1and the second line segment L2, if there exists at least one outer point in each inner side division area among the equally divided areas, then 100 may be assigned to the score, and otherwise 0 may be assigned.

For example, with reference toFIG.10, because there exists an outer point in each of the inner side division areas AP6and AP7associated to the first line segment L1and there, too, exists an outer point in each of the inner side division areas AP2and AP3associated to the second line segment L2, the score of the fourth L-parameter LPS4becomes 100.

Next, the fifth L-parameter LPS5relates to a proportion between the cluster box CB and the shape box SB.

If the size ratio of the shape box SB to the cluster box CB may be equal to or over a predetermined value, then 100 may be assigned to the score, and otherwise 0 assigned.

Preferably, the size ratio may be calculated by use of the longer side lengths of the two boxes.

The first score SC1may be calculated by the following Equation 5 with the above mentioned L-parameters.

Optimal values may be determined for the above weights through tests. Preferably, the fifth weight w5may be greatest, the next greatest one may be the first weight w1or the fourth weight w4, and the second weight w2or the third weight w3may be the next.

In the present embodiment, all of the five L-parameters may be used to calculate the first score, but not limited thereto. For example, only one of the five parameters may be used, and also any two or more may be used together. Preferably, as the parameters for the calculation of the first score, the fifth L-parameter LPS5may be necessarily included, and more preferably, the first and the fourth L-parameters LPS1and LPS4may be included too, without limited thereto.

The calculation of the second score may be detailed with reference toFIG.12.

In the present embodiment, the second score may be calculated by applying weights to two parameters, respectively, but not limited thereto.

For the convenience sake, the parameters may be referred to as I-parameters.

At first, a first I-parameter IPS1relates to the distance variance of the outer points to the second line segment L2(or the reference line segment, the same below), and its score may be determined with the variance to the second line segment L2with reference to TABLE 3 below.

With reference to TABLE 3, if the calculated variance may be below a third predetermined variance value AV3, then 100 may be assigned to the score, if the variance equal to or over the third predetermined variance value AV3and below a fourth predetermined variance value AV4, then 50 assigned, and if the variance equal to or over the fourth predetermined variance value AV4, then 0 assigned.

For example, inFIG.12, assuming that the distance variance of the outer points op8to op12to the second line segment L2may be below the third predetermined variance value AV3, the score for the first I-parameter IPS1becomes 100.

Next, a second I-parameter IPS2relates to the average of minimum relative angles between segments, likewise the third L-parameter LPS3. The second I-parameter IPS2, however, may be calculated only for the second line segment L2.

With reference to12, the second I-parameter IPS2may be determined through TABLE 4 below according to the average angle of the minimum relative angles between segments.

With reference to TABLE 4, for the score of the second I-parameter IPS2, if the average angle may be below a third predetermined angle Ang3, then 100 may be assigned, if the average angle equal to or over the third predetermined angle Ang3and below a fourth predetermined angle Ang4, then 50 assigned, and if the average angle equal to or over the fourth predetermined angle Ang4, then 0 assigned.

For example, assuming that the average angle between segments associated to the second line segment L2, the second I-parameter IPS2may be determined to have the score of 100.

The second score SC2may be calculated by Equation 6 below by use of the above described I-parameters.

In Equation 6, g1and g2may be weights for respective I-parameters.

Optimal values of the weights may be determined through test, too. Preferably, the first weight g1may be greater than the second weight w2, but not limited thereto.

After step321, the roof layer inspection unit158may check whether the mthlayer may be a layer related to the roof of the target object (hereinafter referred to as a “roof layer”), and may output the result of the checking to the first flag assignment analysis unit184and the determination preparation unit152(step322). If the mthlayer may be the roof layer of the target object, the non-reference threshold average AANRm and the non-reference threshold variance AVNRm, which may be used for the m+1th layer in step320, i.e. step468shown inFIG.9, may be increased (step324). In this way, when the non-reference threshold average AANRm and the non-reference threshold variance AVNRm may be increased, conditions to be considered in order to assign the L-shaped flag to the m+1thlayer may be relaxed. The purpose of this may be that, when the target object may be a vehicle, the structural characteristic of the target vehicle in which the front bumper may be rounder than the rear bumper may be reflected in the determination as to whether to assign the L-shaped flag to the m+1thlayer.

Step324may be performed by the first flag assignment analysis unit184, the roof layer inspection unit158, or the determination preparation unit152.

FIG.13is a flowchart of an embodiment322A of step322shown inFIG.4, andFIGS.14to16are diagrams for helping understanding step322A shown inFIG.13.

InFIG.14, the clustering box CB may be a box including the LiDAR points related to the first to Mthlayers, and the shape box SB may be a box including the LiDAR points related to the mthlayer.

According to the embodiment, the roof layer inspection unit158may perform steps602to610shown inFIG.13.

First, referring toFIG.14, whether the first ratio R1of the length XC of the shape box SB of the mthlayer to the length XCL of the clustering box CB related to the target object may be less than a first threshold ratio Rt may be determined as in Equation 7 below (step602).

Here, “XC/XCL” represents the first ratio R1. The first threshold ratio Rt may be set in advance for each of the M layers, or may be set in advance to a constant value regardless of the M layers.

If the first ratio R1may be less than the first threshold ratio Rt, a peak point may be searched for according to each shape flag finally assigned to the mthlayer (step604). For example, the roof layer inspection unit158may determine a LiDAR point located farthest from the shorter one of the first line segment L1and the second line segment L2to be a peak point, or may determine the break point to be a peak point in response to the result of the comparison between the first ratio R1and the first threshold ratio Rt and the result of the final assignment of the shape flag by the final flag assignment unit184.

In detail, in the case in which the L-shaped flag may be finally assigned to the mthlayer, referring toFIG.15(a), the LiDAR point pp1located farthest from the shorter one (L1inFIG.15(a)) of the first line segment L1and the second line segment L2may be determined to be a peak point. Alternatively, in the case in which the I-shaped flag may be finally assigned to the mthlayer, as shown inFIG.15(b), the break point (point located at region B) pp2may be determined to be a peak point.

After step604, whether the second ratio of the length from the peak point to the middle of the clustering box to half the length of the clustering box may be less than a second threshold ratio may be checked (step606). For example, when the L-shaped flag may be finally assigned to the mthlayer and the peak point may be determined to be pp1shown inFIG.15(a), as shown inFIG.16, whether the second ratio R2of the length d1from the peak point pp1to the middle of the clustering box CB to half d2the length of the clustering box CB may be less than the second threshold ratio RA may be checked as in Equation 8 below.

Here, “d1/d2” represents the second ratio R2. The second threshold ratio RA may be set in advance for each of the M layers, or may be set in advance to a constant value regardless of the M layers.

If the second ratio R2is less than the second threshold ratio RA, it is determined that the mthlayer is the roof layer of the target object (step608). However, if the first ratio R1is not less than the first threshold ratio Rt or if the second ratio R2is not less than the second threshold ratio RA, it is determined that the mthlayer is not the roof layer of the target object (step610).

Referring again toFIG.4, after it may be determined that the mthlayer may not be the roof layer of the target object, or after step324, whether m is M is checked (step326). If m is not M, m is increased by 1, and then the process goes to step312(step328). Accordingly, steps312to324are performed on the m+1th layer. That is, the shape flag may be assigned to the m+1th layer in the same method as the method of assigning the shape flag to the mthlayer. For example, steps326and328may be performed by the determination preparation unit152, but the embodiment is not limited thereto.

FIG.17is a flowchart of an embodiment220A of step220shown inFIG.2.

Performing step220, i.e. the determination of the shape of a target object may be made with the process that the shape may be determined basically according to the priority order of the shapes, in which the L-shape comes first, the I-shape next, and the sL-shape last, and then modified according to the first scores or the second score.

Described in brief, though detailed below, the determination according to the priority order may comprise determining first whether there may be a layer of the L-shape flag among the layers for the detected object, and if not, determining whether there may be a layer of the I-shape flag, and if not L-shape nor I-shape, determining whether there may be a layer of the sL-shape flag.

In order to perform the embodiment220A shown inFIG.17, as shown inFIG.3, the target shape determination unit144may include first to fourth flag inspection units192,194,196and197, and a final shape output unit198.

The first flag inspection unit192checks whether there may be a layer to which the break flag has been assigned, among the first to Mthlayers, and outputs the result of the checking to the final shape output unit198(step630). Upon determining that there may be a layer to which the break flag has been assigned, among the first to Mthlayers, based on the result of the checking by the first flag inspection unit192, the final shape output unit198determines that the shape of the target object may be ‘unknown’ (step632).

The second flag inspection unit194, in response to the result from the first inspection unit192that there may be no break-flag layer, checks whether there may be a layer to which the L-shape flag may be assigned (step632), and outputs the check result to the third flag inspection unit196(No in step632) or performs a subsequent check (step633). In case where there may be at least one L-shape flag layer (step632), whether the number of I-shape flag layers may be larger than that of L-shape flag layers (first condition) or the ‘maximum score condition’ (second condition) detailed below may be fulfilled may be subsequently checked (step633), and the result may be output to the final shape output unit198. The final shape output unit198determine I-shape as the target object shape if it may be determined according to the received result that at least one of the first and second conditions may be fulfilled (step634), otherwise L-shape (step635).

In the above description, the ‘maximum score condition’ may be defined that the maximum of the first scores of the L-shape flag layers may be below a first predetermined score and the maximum of the second scores of the I-shape flag layers may be equal to or over a second predetermined score. If there may be a L-shape flag layer, then the shape of the target object may be determined by the L-shape flag according to the priority order rule, however, nonetheless, if there may be a I-shape flag which may represent better the heading, in other words, the maximum score condition may be fulfilled, then more precise heading information may be obtained by determining the shape of the target object to be the I-shape flag.

Upon recognizing that there may be no layer to which the L-shaped flag has been assigned based on the result of the checking by the second flag inspection unit194, the third flag inspection unit196checks whether there may be a layer to which the I-shaped flag has been assigned (step636) and outputs the result of the checking to the final shape output unit198. Upon recognizing that there may be no layer to which any one of the break flag and the L-shaped flag has been assigned but there may be a layer to which the I-shaped flag has been assigned, among the first to Mthlayers, based on the results of the checking by the first to third flag inspection units192,194and196, the final shape output unit198determines that the target object has an “I” shape (step634). The third flag inspection unit196, on the other hand, if it is determined that there is no I-shape flag layer in step636(No in step636), may output the result to the fourth flag inspection unit197.

The fourth flag inspection unit197, in response to the result from the third flag inspection unit196, checks whether there is a layer to which a sL-shape flag is assigned (step637), and outputs the check result to the final shape output unit198. If there is no sL-shape flag layer according to the result checked by the fourth flag inspection unit197, then the final shape output unit198determines the shape of the target object as ‘unknown’ (step640). On the other hand, if it is determined that there is a sL-shape flag layer (Yes in step637), then fourth flag inspection unit197subsequently checks whether the maximum score of the second scores of the sL-shape flag layers is equal to or over a third predetermined score (step638), and outputs the result to the final shape output unit198. The final shape output unit198may determine the shape of the target object as sL-shape if the maximum score is equal to or over the third predetermined score (step639), and otherwise ‘unknown’ (step640).

As described above, when the final shape output unit198determines the shape of the target object, the break flag, the L-shaped flag, the I-shaped flag, and the sL-shaped flag may be checked in that order.

On the other hand, upon recognizing that there may be no layer to which any one of the break flag, the L-shaped flag, and the I-shaped flag has been assigned, among the first to Mthlayers, based on the results of the checking by the first to fourth flag inspection units192,194,196and197, the final shape output unit198determines that the shape of the target object may be ‘unknown.’

FIG.18shows various types of target vehicles710to716on the basis of the host vehicle700.

Referring toFIG.18, the target vehicle716, only the side surface of which may be scanned from the host vehicle700, has an I-shaped contour, and the target vehicles710,712and714, the side surfaces and the bumpers of which may be scanned from the host vehicle700, have L-shaped (including sL-shaped) contours. A moving object in a downtown area or an expressway mainly has an L-shaped contour or an I-shaped contour. Therefore, it may be possible to temporarily determine in step318whether an object has an I-shaped contour or an L-shaped contour based on the size of the shape box SB having the form of a contour.

The contour of a target vehicle, which may be a target object, may be determined by the object-tracking device100and the object shape analysis method200using a LiDAR sensor according to the embodiments described above. For example, referring toFIG.18, the target vehicles710,712and714may be determined to have L-shaped contours, and the target vehicle716may be determined to have an I-shaped contour. In this case, the object-tracking device100according to the embodiment may recognize the heading directions of the target vehicles710to716using the determined contours of the target vehicles. For example, when the target vehicles710to716have L-shaped and I-shaped contours, the heading directions of the target vehicles710to716may be directions (e.g. HD1, HD2, HD3and HD4shown inFIG.18) parallel to the longer one of the first line segment L1and the second line segment L2.

To determine the heading of a detected object, it may be necessary to select a layer or flag (hereinafter, referred to as ‘heading layer’ or ‘heading flag’) for using for the determination among the corresponding layers.

In the present embodiment, the L-shape flag, of which the first score may be greatest among all the L-shape flags, may be determined to be the heading flag if L-shape flag may be determined as the shape of the target object, the I-shape flag, of which the second score may be greatest among all the I-shape flags, may be determined to be the heading flag if I-shape flag may be determined as the shape of the target object, and the sL-shape flag, of which the first score may be greatest among all the sL-shape flags, may be determined to be the heading flag if sL-shape flag may be determined as the shape of the target object. That is, the heading of the corresponding object may be determined according to the maximum score rule among the same shape flags as the one determined as the shape of the corresponding object.

A result of the embodiment of the present disclosure may be compared below with that of a comparative example method for determining the shape of a target object.

The comparative example method determines the shape of objects only according to the priority order rule without considering the first and second scores. Also, according to the comparative example method, the flag or layer which has the smallest of the mean and variance values of the distances of the associated outer points even only for any one of the first and second line segments L1and L2may be determined to be the heading flag or layer.

First, with reference toFIG.19, layer0to3data of LiDAR points for a test object are shown.

It may be shown that the outer outline OL-0formed by connecting the outer points of the LiDAR points on the layer0corresponds to the L-shape with the second line segment L2oriented along the left-upper direction with largely angled with the ground truth, and the first score therefor may be 46.25.

And, it may be shown that the outer outline OL-1formed by connecting the outer points of the LiDAR points on the layer1corresponds to the L-shape with the direction of the second line segment L2well matched to the ground truth with a small angle, and the first score therefor may be 65.5.

It may be also shown that the outer outline OL-2formed by connecting the outer points of the LiDAR points on the layer2corresponds to the L-shape with the direction of the second line segment L2angled with the ground truth with a larger angle than in the case of the layer1, and the first score therefor may be 65.5.

For the layer3, it may be shown that the outer outline OL-3formed by connecting the outer points of the LiDAR points thereon corresponds to the L-shape with the direction of the second line segment L2angled with the ground truth with a larger angle than in the case of the layer2, and the first score therefor may be 61.5.

According to the comparative example method, with respect to the distance variance of outer points to each line segment, because the distance variance of the associated outer points to the first line segment L1in the layer0may be smallest among those in the layers, the layer0may be selected as the heading layer. However, according to the embodiment, because the heading layer for the cases of the L-shape and sL-shape may be determined by considering a comparison result of first scores thereof in addition to the result of the priority order rule, the layer1may be accordingly selected as the heading layer.

The comparative example method may be problematic in that the heading of the corresponding object may be wrongly determined to be directed toward the left-upper direction due to the determination of the heading layer of the layer0, however, the problem may be solved in the embodiment by use of the scores.

For another comparison result, with reference toFIG.20, the I-shape may be determined for the layer0, and the L-shape for the layer1, with the second score for the layer0being 80 and the first score for the layer1being 67.75.

In this case, according to the comparative example method, the shape of the corresponding object may be determined to be the L-shape according to the priority order rule because there exist a L-shape flag, and the layer1may be selected as the heading layer. However, according to the embodiment of the present disclosure, because though the L-shape flag may be determined to be in exist in the above described step632, the maximum score condition may be satisfied in step633, the layer0, which may be closer to the ground truth, may be selected as the heading layer.

On the other hand, the present disclosure described above may be embodied as computer-readable code on a medium in which a program may be recorded. The computer-readable medium includes all types of recording devices in which data readable by a computer system may be stored. Examples of the computer-readable medium include a hard disk drive (HDD), a solid-state drive (SSD), a silicon disk drive (SDD), a ROM, a RAM, a CD-ROM, a magnetic tape, a floppy disk, an optical data storage device, etc. Therefore, the above detailed description should not be construed as restrictive and should be considered as illustrative in all respects. The scope of the present disclosure should be determined by a reasonable interpretation of the appended claims, and all modifications within the equivalent scope of the present disclosure may be included in the scope of the present disclosure.