A lane heat map drawing method based on a high-precision road network

Abstract

The application discloses a lane heat map drawing method based on a high-precision road network, and comprises the following steps: step S1, constructing an initialization environment; the step S1 specifically comprises the following steps: step S2, creating a heat map mounting plane on a three-dimensional lane according to a plurality of point coordinates in lane initial points and end points; the specific creation steps are as follows: step S201, coordinate point specification processing, keeping a fixed relative distance between the generated lane heat map and the road network during data processing; step S202, creating a point set by processing the data of step S201; step S203, copying a heat map geometric body, and adjusting a vertical direction coefficient according to a space coordinate system. Through the method in the application, a basic road network polygon plane is generated in a three-dimensional space and serves as a carrier of a lane heat map in the three-dimensional space, so that the three-dimensional effect of the lane heat map is directly and quickly presented, and specific information that needs to be displayed by the lane in real time is expressed.

Description

Technical Field

[0001] This invention belongs to the field of scientific data visualization technology, specifically a method for drawing lane heat maps based on high-precision road networks. Background Technology

[0002] A heatmap, also known as a heat map, heat table, or density table, is primarily used to display the distribution of data. A standard heatmap maps the coordinates of two-dimensional heat points onto the X and Y axes, and its values ​​are dynamically calculated using color gamut mapping. Early heatmaps were simply rectangles with color coding; current models are more flexible and can produce smoothed heatmaps, finding wide application in scientific fields such as biology and geography, as well as in the internet industry.

[0003] The heat map data provided by the high-precision road network contains more than just two-dimensional spatial heat maps. Most of what we encounter in our daily lives are three-dimensional spatial coordinates, but they are usually converted into two-dimensional coordinate information. The information expressed by the lane heat map is basically limited to two-dimensional space and cannot express the three-dimensional spatial information of the entire lane heat map in a deeper way. Summary of the Invention

[0004] The purpose of this invention is to provide a method for drawing lane heat maps based on high-precision road networks, so as to solve the problem that in the prior art, the information expressed by lane heat maps is basically limited to two-dimensional space and cannot express the three-dimensional spatial information of the entire lane heat map in a deeper way.

[0005] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows:

[0006] A method for creating lane heatmaps based on high-precision road networks includes the following steps:

[0007] Step S1, construct the initialization environment; constructing the initialization environment specifically includes:

[0008] Step S101: Initialize and clean the original high-precision road network data;

[0009] Step S102: Generate a basic road network polygon plane in three-dimensional space, which serves as the carrier of the lane heat map in three-dimensional space.

[0010] Step S2: Based on the coordinates of the initial and ending points of the lane, create a heat map mounting plane on the 3D lane; the specific creation steps are as follows:

[0011] Step S201: Coordinate point standardization processing. During the data processing, the generated heat map data is processed according to the coordinate point standardization to maintain consistency. The heat map is always kept above the road network to avoid the heat map and the road network being on the same level, which would cause the browser to flicker in the rendering level.

[0012] Step S202: Create a point set PathPointList from the coordinate point data processed in step S201. The point set mainly includes the center point coordinates of the lane, the distance from the edge line, the vertex coordinates of the heat map plane, and the point index value.

[0013] Step S203: Copy the point set PathPointList created in step S202, and adjust the vertical direction coefficient according to the spatial coordinate system; specifically: make a relative distance offset between the high-precision road network and the lane heat map in the y-axis direction, and configure the lane heat map according to the information, display coefficient and specific lane ID to be displayed on the heat map as needed;

[0014] Step S3: Complete the lane heat map drawing.

[0015] According to the above technical solution, in step S101, data cleaning specifically involves:

[0016] Step A1: First, load the original high-precision road network and obtain the original high-precision road network JSON string; deserialize the obtained high-precision road network JSON string using the parse method in the JSON method; extract and encapsulate the intersection, road segment, and sign attribute information in the high-precision road network into a class.

[0017] Step A2: Based on the different classes obtained in Step A1, each class encapsulates the coordinates of points in the spatial coordinate system. The coordinates of all points in the spatial coordinate system can be retrieved by using the class.

[0018] Step A3, then create an array to store vertices, vertex information, multi-face indexes and single-face material layers based on the coordinates.

[0019] According to the above technical solution, in step S102, generating the basic road network polygon plane specifically involves:

[0020] Step B1: Based on the cleaned data in step S101, generate the basic road network polygon plane in three-dimensional space using the geometry generation method in the Three.js library;

[0021] Step B2: Divide the coordinates of the center point of the road in the high-precision road network into equal parts, and use the vector vertical direction and vector normalization to constrain the trajectory coordinates at the turning point of the lane.

[0022] Step B3: Obtain the center points of the road's starting and ending points to determine the coordinates of multiple center points between the starting and ending points on the lane centerline. Specifically, the road center point is determined by the width of the road, i.e., the point at which the road width is halfway down is the road centerline. The two ends of the centerline are the starting and ending points of the road. The coordinates of the points picked from the centerline are the required center point coordinates. The more center point coordinates used, the more detailed the lane heat map will be.

[0023] According to the above technical solution, the specific processing method of step S201 is as follows:

[0024] Determine a subset of vectors, pass the vectors into the difference product for processing, and perform vector normalization: use the Vector3 three-dimensional vector processing method in Three.js to process the coordinates of a single point into a sub-vector, as shown in Equation (1);

[0025] Point.dir=SubVectors(point[i+1],point[i]) (1)

[0026] In equation (1), point[i+1] is the first point in the point set, and point[i+1] is the second point in the point set. Here, i is the index of the point set during traversal processing, and the vector values ​​of the two points are processed by traversal; point is the point set, SubVectors is the method to obtain subvectors, and Point.dir is the value of the subvector;

[0027] The sub-vectors and normalized results are processed using the method of cross vectors in three-dimensional vectors, as shown in Equation (2):

[0028] Point.right=CrossVectors(Point.dir,new THREE.Vector3(0,1,0)).normalize(); (2)

[0029] In equation (2), Point.dir is the value of the subvector, CrossVectors is the method for obtaining the cross vector, and Point.right is the normalization method for the cross vector;

[0030] Then, the vector distance between the center point sub-vector and the road network edge line is processed by equation (3) to ensure that the distance between the center line and the edge line is consistent in straight lines and curves. Equation (3) is as follows:

[0031] Point.up=CrossVectors(Point.right,Point.dir).normalize() (3)

[0032] In equation (3), CrossVectors is the method for obtaining cross vectors, and Point.up is the normalized value of the cross vector and the subvector.

[0033] According to the above technical solution, the specific processing method of step S202 is as follows:

[0034] Update the heatmap geometry according to the PathPointList instance, copy the distance vector between the center point and the edge, pass in the heatmap width, and determine the turning angle of the heatmap layer with different widths, as shown in equation (4) below:

[0035] Right=right.copy(pathPoint.right).multiplyScalar(halfWidth / 2) (4)

[0036] In equation (4), halfWidth is the width of the heatmap, right.copy is the distance vector between the copy center point and the edge, and multiplyScalar is the turning angle between the heatmap and the edge;

[0037] Using a three-dimensional vector processing method, the left and right offsets are smoothed based on the distance between the center point and the edge line, as shown in equation (5):

[0038] leftOffset.fromArray(position,position.length).sub(Right) (5)

[0039] In equation (5), leftOffset is the offset, fromArray is the distance processing method, which takes position as the center point and position.Length as the distance between the center point and the edge; sub(Right) is the coordinate of the right point; the distance between the center point and the edge is processed by fromArray to perform offset smoothing.

[0040] Using a three-dimensional vector processing method, the absolute value of the distance between the center point and the edge line is processed by equation (6); equation (6) is as follows:

[0041] tempPoint1.copy(leftOffset).setLength(Math.abs(leftOffset.length)).add(left) (6)

[0042] In equation (6), setLength is the absolute value length of the offset; Math.abs is the mathematical formula for calculating the absolute value; leftOffset.length is the value of the offset; add(left) is the direction of the offset; and tempPoint1.copy(leftOffset) is the new coordinates after the offset is copied.

[0043] Compared with the prior art, the present invention has the following beneficial effects:

[0044] The method in this invention utilizes a basic road network polygonal plane generated in three-dimensional space, which serves as a carrier for the lane heat map in three-dimensional space, directly and quickly presenting the three-dimensional effect of the lane heat map and expressing the specific information that the lane needs to display in real time. Attached Figure Description

[0045] Figure 1 This is a schematic diagram of the multi-point heat map substrate generation of the present invention. Detailed Implementation

[0046] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0047] Example 1

[0048] like Figure 1 As shown, a method for creating lane heatmaps based on high-precision road networks includes the following steps:

[0049] Step S1, construct the initialization environment; constructing the initialization environment specifically includes:

[0050] Step S101: Initialize and clean the original high-precision road network data;

[0051] Step S102: Generate a basic road network polygon plane in three-dimensional space, which serves as the carrier of the lane heat map in three-dimensional space.

[0052] Step S2: Based on the coordinates of the initial and ending points of the lane, create a heat map mounting plane on the 3D lane; the specific creation steps are as follows:

[0053] Step S201: Coordinate point standardization processing. During the data processing, the generated heat map data is processed according to the coordinate point standardization to maintain consistency. The heat map is always kept above the road network to avoid the heat map and the road network being on the same level, which would cause the browser to flicker in the rendering level.

[0054] Step S202: Create a point set PathPointList from the coordinate point data processed in step S201. The point set mainly includes the center point coordinates of the lane, the distance from the edge line, the vertex coordinates of the heat map plane, and the point index value.

[0055] Step S203: Copy the point set PathPointList created in step S202, and adjust the vertical direction coefficient according to the spatial coordinate system; specifically: make a relative distance offset between the high-precision road network and the lane heat map in the y-axis direction, and configure the lane heat map according to the information, display coefficient and specific lane ID to be displayed on the heat map as needed;

[0056] Step S3: Complete the lane heat map drawing.

[0057] The method in this invention utilizes a basic road network polygonal plane generated in three-dimensional space, which serves as a carrier for the lane heat map in three-dimensional space, directly and quickly presenting the three-dimensional effect of the lane heat map and expressing the specific information that the lane needs to display in real time.

[0058] Example 2

[0059] This embodiment is a further refinement of Embodiment 1.

[0060] In step S101, data cleaning specifically involves:

[0061] Step A1: First, load the original high-precision road network and obtain the original high-precision road network JSON string; deserialize the obtained high-precision road network JSON string using the parse method in the JSON method; extract and encapsulate the intersection, road segment, and sign attribute information in the high-precision road network into a class.

[0062] Step A2: Based on the different classes obtained in Step A1, each class encapsulates the coordinates of points in the spatial coordinate system. The coordinates of all points in the spatial coordinate system can be retrieved by using the class.

[0063] Step A3, then create an array to store vertices, vertex information, multi-face indexes and single-face material layers based on the coordinates.

[0064] In step S102, generating the basic road network polygon plane specifically involves:

[0065] Step B1: Based on the cleaned data in step S101, generate the basic road network polygon plane in three-dimensional space using the geometry generation method in the Three.js library;

[0066] Step B2: Divide the coordinates of the center point of the road in the high-precision road network into equal parts, and use the vector vertical direction and vector normalization to constrain the trajectory coordinates at the turning point of the lane.

[0067] Step B3: Obtain the center points of the road's starting and ending points to determine the coordinates of multiple center points between the starting and ending points on the lane centerline. Specifically, the road center point is determined by the width of the road, i.e., the point at which the road width is halfway down is the road centerline. The two ends of the centerline are the starting and ending points of the road. The coordinates of the points picked from the centerline are the required center point coordinates. The more center point coordinates used, the more detailed the lane heat map will be.

[0068] The specific processing method for step S201 is as follows:

[0069] Determine a subset of vectors, pass the vectors into the difference product for processing, and perform vector normalization: use the Vector3 three-dimensional vector processing method in Three.js to process the coordinates of a single point into a sub-vector, as shown in Equation (1);

[0070] Point.dir=SubVectors(point[i+1],point[i]) (1)

[0071] In equation (1), point[i+1] is the first point in the point set, and point[i+1] is the second point in the point set. Here, i is the index of the point set during traversal processing, and the vector values ​​of the two points are processed by traversal; point is the point set, SubVectors is the method to obtain subvectors, and Point.dir is the value of the subvector;

[0072] The sub-vectors and normalized results are processed using the method of cross vectors in three-dimensional vectors, as shown in Equation (2):

[0073] Point.right=CrossVectors(Point.dir,new THREE.Vector3(0,1,0)).normalize(); (2)

[0074] In equation (2), Point.dir is the value of the subvector, CrossVectors is the method for obtaining the cross vector, and Point.right is the normalization method for the cross vector;

[0075] Then, the vector distance between the center point sub-vector and the road network edge line is processed by equation (3) to ensure that the distance between the center line and the edge line is consistent in straight lines and curves. Equation (3) is as follows:

[0076] Point.up=CrossVectors(Point.right,Point.dir).normalize() (3)

[0077] In equation (3), CrossVectors is the method for obtaining cross vectors, and Point.up is the normalized value of the cross vector and the subvector.

[0078] The specific processing method for step S202 is as follows:

[0079] Update the heatmap geometry according to the PathPointList instance, copy the distance vector between the center point and the edge, pass in the heatmap width, and determine the turning angle of the heatmap layer with different widths, as shown in equation (4) below:

[0080] Right=right.copy(pathPoint.right).multiplyScalar(halfWidth / 2) (4)

[0081] In equation (4), halfWidth is the width of the heatmap, right.copy is the distance vector between the copy center point and the edge, and multiplyScalar is the turning angle between the heatmap and the edge;

[0082] Using a three-dimensional vector processing method, the left and right offsets are smoothed based on the distance between the center point and the edge line, as shown in equation (5):

[0083] leftOffset.fromArray(position,position.length).sub(Right) (5)

[0084] In equation (5), leftOffset is the offset, fromArray is the distance processing method, which takes position as the center point and position.Length as the distance between the center point and the edge; sub(Right) is the coordinate of the right point; the distance between the center point and the edge is processed by fromArray to perform offset smoothing.

[0085] Using a three-dimensional vector processing method, the absolute value of the distance between the center point and the edge line is processed by equation (6); equation (6) is as follows:

[0086] tempPoint1.copy(leftOffset).setLength(Math.abs(leftOffset.length)).add(left) (6)

[0087] In equation (6), setLength is the absolute value length of the offset; Math.abs is the mathematical formula for calculating the absolute value; leftOffset.length is the value of the offset; add(left) is the direction of the offset; and tempPoint1.copy(leftOffset) is the new coordinates after the offset is copied.

[0088] The location of lanes in the high-precision road network is calculated, and then a lane heat map is drawn in real time based on the specific information in the lanes.

[0089] This invention consists of two main steps: high-precision road network lane data processing and heat map drawing. These two steps include data processing of multiple points in the high-precision road network and real-time drawing of multi-level heat map spatial coordinates; thus forming a construction method for constructing lane heat maps based on real-time high-precision road network data.

[0090] Example 3

[0091] The inventive concept of this invention is as follows: Step 1, constructing the initialization environment, which consists of the following two basic conditions:

[0092] Condition 1: Initialize and clean the original high-precision road network data. First, load the original serialized high-precision road network and deserialize it. Extract and encapsulate the attribute information such as intersections, road segments, and signs in the road network into classes. Then, according to different classes, query and obtain the coordinates of all points in the spatial coordinate system. Then, create an array to store vertices, vertex information and multi-face index, and single-face material layer based on the coordinates.

[0093] Condition 2: Based on the array, multi-face index, and material layer data generated in Condition 1, a basic road network polygon plane is generated in 3D space using the geometry generation method in the Three.js library. This serves as the carrier for the lane heatmap in 3D space. The carrier is typically a 3D lane plane. Then, the coordinates of the trajectory points at the road center in the high-precision road network are equally divided, and the vertical direction of the vector and the normalization of the vector are used to constrain the trajectory coordinates at lane turns. Finally, the center points of the road's starting and ending points can be obtained, thereby determining the coordinates of multiple points between the starting and ending points on the lane centerline.

[0094] Step 2: Based on the coordinates of multiple points in the initial and ending points of the lane, create a heat map mounting plane on the three-dimensional lane.

[0095] Step a: Standardize coordinate points to ensure that the generated lane heatmap always maintains a fixed relative distance from the road network during data processing. Therefore, when using the polygon generation method in Three.js, it is necessary to ensure that the density of the center trajectory points is consistent with that in the straight line when the lane enters the curve from the straight line; determine the vector subset, pass the vector into the difference product processing, and perform vector normalization; Formula (1) is to use the Vector3 three-dimensional vector processing method in Three.js to process the sub-vector of the coordinates of a single point, clarify the direction of the vector, and ensure that the rendering is a single-sided rendering; Formula (2) is to introduce the data processed in Formula (1) and use the method of cross vector in three-dimensional vector to process the sub-vector and the result of normalization; Formula (3) is to process the vector distance between the center point sub-vector and the road network edge line to ensure that the distance between the center line and the edge line is consistent in the straight line and the curve.

[0096] Point.dir=SubVectors(point[i+1],point[i]); (1)

[0097] Point.right=CrossVectors(Point.dir,new THREE.Vector3(0,1,0)).normalize(); (2)

[0098] Point.up=CrossVectors(Point.right,Point.dir).normalize(); (3)

[0099] Step b: Create a point set PathPointList from the data processed in step a. The point set mainly includes the center point coordinates of the lane, the distance from the edge line, the vertex coordinates of the heat map plane, and the point index value. Update the heat map geometry according to the instance of PathPointList. Formula (4) copies the distance vector between the center point and the edge line, passes in the heat map width, and determines the turning angle of the heat map layer with different widths. Formula (5) uses the three-dimensional vector processing method to perform left and right offset smoothing based on the distance between the center point and the edge line. Formula (6) performs absolute value processing based on the point coordinates, copies the point information, and improves performance.

[0100] Right=right.copy(pathPoint.right).multiplyScalar(halfWidth / 2); (4)

[0101] leftOffset.fromArray(position,position.length).sub(Right); (5)

[0102] tempPoint1.copy(leftOffset).setLength(Math.abs(leftOffset.length)).add(left); (6)

[0103] Step c: Clone and copy the heatmap geometry, adjust the vertical direction coefficient according to the spatial coordinate system, make relative distance offsets between the high-precision road network and lane heatmaps in the y-axis direction, and configure the lane heatmap according to the display coefficients and specific lane IDs.

[0104] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0105] Finally, it should be noted that the above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for drawing lane heatmaps based on high-precision road networks, characterized in that: Includes the following steps: Step S1, construct the initialization environment; constructing the initialization environment specifically includes: Step S101: Initialize and clean the original high-precision road network data; Step S102: Generate a basic road network polygon plane in three-dimensional space, which will serve as the carrier of the lane heatmap in three-dimensional space; the specific steps for generating the basic road network polygon plane are as follows: Step B1: Based on the cleaned data in step S101, generate the basic road network polygon plane in three-dimensional space using the geometry generation method in the Three.js library; Step B2: Divide the coordinates of the center point of the road in the high-precision road network into equal parts, and use the vector vertical direction and vector normalization to constrain the trajectory coordinates at the turning point of the lane. Step B3: Obtain the center points of the road's starting and ending points to determine the coordinates of multiple center points between the starting and ending points on the lane centerline. Specifically, the road center point is determined by the width of the road, which is halfway down the road. The two ends of the centerline are the starting and ending points of the road. The coordinates of the points picked from the centerline are the required center point coordinates. The more center point coordinates used, the more detailed the lane heatmap will be. Step S2: Based on the coordinates of the initial and ending points of the lane, create a heat map mounting plane on the 3D lane; the specific creation steps are as follows: Step S201: Coordinate point standardization processing. During the data processing, the generated heat map data is processed according to the coordinate point standardization to maintain consistency. The heat map is always kept above the road network to avoid the heat map and the road network being on the same level, which would cause the browser to flicker in the rendering level. Step S202: Create a point set PathPointList from the coordinate point data processed in step S201. The point set mainly includes the center point coordinates of the lane, the distance from the edge line, the vertex coordinates of the heat map plane, and the point index value. Step S203: Copy the point set PathPointList created in step S202, and adjust the vertical direction coefficient according to the spatial coordinate system; specifically: make a relative distance offset between the high-precision road network and the lane heat map in the y-axis direction, and configure the lane heat map according to the information, display coefficient and specific lane ID to be displayed on the heat map as needed; Step S3: Complete the lane heat map drawing.

2. The method for drawing lane heatmaps based on high-precision road networks according to claim 1, characterized in that: In step S101, data cleaning specifically involves: Step A1: First, load the original high-precision road network and obtain the original high-precision road network JSON string; deserialize the obtained high-precision road network JSON string using the parse method in the JSON method; extract and encapsulate the intersection, road segment, and sign attribute information in the high-precision road network into a class. Step A2: Based on the different classes obtained in Step A1, each class encapsulates the coordinates of points in the spatial coordinate system. The coordinates of all points in the spatial coordinate system can be retrieved by using the class. Step A3, then create an array to store vertices, vertex information, multi-face indexes and single-face material layers based on the coordinates.

3. The method for drawing lane heatmaps based on high-precision road networks according to claim 1, characterized in that: The specific processing method for step S201 is as follows: Determine a subset of vectors, pass the vectors into the difference product for processing, and perform vector normalization: use the Vector3 three-dimensional vector processing method in Three.js to process the coordinates of a single point into a sub-vector, as shown in equation (1); Point.dir = SubVectors(point[i+1], point[i]) (1) In equation (1), point[i+1] is the first point in the point set, and point[i+1] is the second point in the point set. Here, i is the index of the point set during traversal processing, and the vector values ​​of the two points are processed by traversal; point is the point set, SubVectors is the method to obtain subvectors, and Point.dir is the value of the subvector; The sub-vectors and normalized results are processed using the method of cross vectors in three-dimensional vectors, as shown in equation (2): Point.right = CrossVectors(Point.dir, new THREE.Vector3(0, 1, 0)).normalize(); (2) In equation (2), Point.dir is the value of the subvector, CrossVectors is the method for obtaining the cross vector, and Point.right is the normalization method for the cross vector; Then, the vector distance between the center point sub-vector and the road network edge line is processed by equation (3) to ensure that the distance between the center line and the edge line is consistent in straight lines and curves. Equation (3) is as follows; Point.up = CrossVectors(Point.right, Point.dir).normalize()(3) In equation (3), CrossVectors is the method for obtaining cross vectors, and Point.up is the normalized value of the cross vector and the subvector.

4. The method for drawing lane heatmaps based on high-precision road networks according to claim 1, characterized in that: The specific processing method for step S203 is as follows: Update the heatmap geometry according to the PathPointList instance, copy the distance vector between the center point and the edge, pass in the heatmap width, and determine the turning angle of the heatmap layer with different widths, as shown in equation (4) below: Right = right.copy(pathPoint.right).multiplyScalar(halfWidth / 2)(4) In equation (4), halfWidth is the width of the heatmap, right.copy is the distance vector between the copy center point and the edge, and multiplyScalar is the turning angle between the heatmap and the edge; Using a three-dimensional vector processing method, the left and right offsets are smoothed based on the distance between the center point and the edge line, as shown in equation (5): leftOffset.fromArray(position, position.length).sub(Right) (5) In equation (5), leftOffset is the offset, fromArray is the distance processing method, and the center point of position and the distance between the center point and the edge are passed in; sub(Right) is the coordinate of the right point; the distance between the center point and the edge is processed by fromArray to perform offset smoothing; Using a three-dimensional vector processing method, the absolute value of the distance between the center point and the edge line is processed by equation (6); equation (6) is as follows: tempPoint1.copy(leftOffset).setLength(Math.abs(leftOffset.length)).add(left)(6) In equation (6), setLength is the absolute value length of the offset; Math.abs is the mathematical formula for calculating the absolute value; leftOffset.length is the value of the offset; add(left) is the direction of the offset; tempPoint1.copy(leftOffset) is the new coordinates after the offset is copied.

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