A method for constructing a dynamic occlusion spatial model of the visible area of ​​highway curved roadside landscape

Abstract

The present invention discloses a dynamic occlusion spatial model of the visual domain of the roadside landscape of a curved highway. By constructing a dynamic spatial model of the visual process of the curved roadside landscape, a calculation equation of the roadside landscape visual domain is derived, and a dynamic occlusion ratio is defined by spatial coordinates, and a judgment model of the roadside landscape visual domain being blocked is proposed; finally, the created visual domain model is used to calculate and analyze the actual road section, and the results verify the correctness and effectiveness of the model. The visual domain model of the curved roadside landscape of the present invention provides a design basis for the setting of the curved roadside landscape of the highway, plant planting, highway land acquisition scope, etc., and provides model support for creating the closedness and openness of the roadside landscape of the highway.

Description

Technical Field

[0001] The invention belongs to the technical field of highway engineering, and in particular relates to a dynamic occlusion space model of a visible area of ​​a curved roadside landscape of a highway. Background Art

[0002] With the vigorous promotion and development of concepts such as ecological highways, tourist highways, and environmentally friendly highways, the roadside landscape of highways has received more and more attention. Many scholars' research has also shown that good highway roadside landscapes play a certain role in reducing traffic accidents. Since the highway roadside landscape can be achieved by borrowing scenery, and at the same time, for traffic safety, the driver cannot be distracted by too rich scenery, so the occlusion of the highway roadside landscape and its occlusion degree control are the key issues that need to be studied in the highway roadside landscape visual domain.

[0003] This paper summarizes and analyzes the research on roadside landscape at curves at home and abroad, and finds that the current research on obstruction of roadside landscape at curves at home and abroad has the following limitations: At present, most of the research on highway traffic signs is focused on the visibility and layout design of signs, but there is still a lack of research on the impact of obstruction on signs; There are many studies on the probability of signs being obstructed by same-direction vehicles, and some dynamic obstruction probability models have been established, but these obstruction models only solve the problem of same-direction vehicles obstructing signs, while signs are affected by many factors in the actual obstruction process. The unreasonable setting of highway curve signs, plant planting, slope of roadside slopes, location of sound insulation walls, etc. lead to obstruction of signs, which in turn becomes a potential accident hazard.

[0004] Therefore, it is necessary to establish a dynamic occlusion spatial model of the visible domain of curved roadside landscape to accurately represent the actual occlusion process, so as to propose corresponding solutions for the occlusion elements in the visible domain and reduce the occurrence of traffic accidents on curved road sections. Summary of the invention

[0005] In view of the above problems, the present invention provides a spatial model of dynamic occlusion of the visual domain of the roadside landscape on a curved highway. The present invention studies the problem of dynamic occlusion of the visual domain of the roadside landscape on a curved highway, constructs a dynamic spatial model of the visual process of the curved roadside landscape based on the depth of vision and the visual distance of the driver of a vehicle traveling at high speed, derives the calculation equation of the roadside landscape visual domain, defines the dynamic occlusion ratio through spatial coordinates, and proposes a judgment model for the occlusion of the roadside landscape visual domain; based on this, the standard design parameters of the actual road section are adopted, and the occlusion rules of the roadside landscape visual domain at different positions by occluders of different widths and heights and occluders of the same width and height are analyzed through MATLAB, so as to propose the roadside landscape anti-occlusion clearance control value and control content.

[0006] The present invention is achieved through the following technical solutions:

[0007] A dynamic occlusion spatial model of the visual domain of the curved roadside landscape of a highway. The spatial model is a vehicle driving from point A to any point t i The roadside landscape visual domain occlusion model at point B at time is expressed by the volume occlusion ratio:

[0008]

[0009] Taking the center of the circular curve of the highway curve as the origin (0,0,0), the coordinates of the driver's position point A are (0, –(R+w1+w2),h); at the same time, taking the viewing plane as the reference plane, the visible area volume of the roadside landscape at point A is:

[0010]

[0011] When the driver drives from point A to point B, the driving angle is δ, and the arc length of the driving distance is L a for:

[0012]

[0013] Thus we can get:

[0014]

[0015] Then, the coordinates of point B are:

[0016]

[0017] Through trigonometric conversion, the coordinates of point B are simplified to:

[0018]

[0019]

[0020] In the formula,

[0021] V A : The visible volume of the roadside landscape at point A, in m 3 ;

[0022] Α: horizontal viewing angle, varies with speed, unit: °;

[0023] α1: the viewing angle not blocked by the central dividing strip, unit: °;

[0024] L: sight distance, which varies with speed. The sight distance L here refers to the sight distance depth, which is divided into the front sight distance L1, the sight distance concentration point (L1+L2), and the sight distance depth (L1+L2+L3), in meters;

[0025] Β: vertical viewing angle, which is the sum of β1 and β2, unit: °;

[0026] β1: the upper vertical angle of the viewing plane, unit: °;

[0027] β2: The vertical angle of the visual plane, that is, the vertical angle not blocked by the visible distance in front of the vehicle, unit: °;

[0028] h: visual height, 1.2m for cars and 2.0m for trucks, unit: m;

[0029] R0: The radius of the highway curve, simulated by the minimum radius of the circular curve, unit: m;

[0030] R: The curve radius of the highway roadbed edge line, in m;

[0031] w1: the width of the lane edge from the inner curved roadbed edge to the outer curved median edge, in m;

[0032] w2: width from the outer edge of the outer curve median lane to the coordinate position of the car, in meters;

[0033] v: vehicle speed, in km / h.

[0034] t i : The travel time of a vehicle from point A to point B, in seconds.

[0035] D: width of the obstruction, in m;

[0036] H: height of the obstruction, in m;

[0037] x z : X coordinate value of the occluder, in meters.

[0038] The construction of the highway curve sign visual area model of the present invention comprises the following steps:

[0039] (1) Analyze the high-risk roadside landscape conditions of the curved road accident, and analyze the factors that dynamically block the visual area of ​​the curved roadside landscape from various aspects.

[0040] (2) Define the visible area of ​​the curved roadside landscape:

[0041] During the vehicle movement, the visible area of ​​the curved roadside landscape is as follows: Figure 1As shown in the figure, it is the cone enclosed by the tangent line of the left side of the driver's visual height h to the central dividing strip, the right side field of vision and the depth of visibility. The obstruction of the visual domain of the curved roadside landscape means that under certain vehicle speed conditions, assuming that the driver's head does not move and only looks at the front of the highway, there are obstructions in the driver's visual domain, making it impossible for the driver to see the roadside landscape from the right side of the roadbed or the roadside landscape is partially obstructed, thus affecting the integrity of the roadside landscape.

[0042] (3) Construct a dynamic occlusion space model for the visual process of the highway curve roadside landscape:

[0043] 1) The volume calculation equation of the visible area of ​​the highway curve roadside landscape is:

[0044] like Figure 2 As shown in the figure, taking the center of the circular curve of the highway curve as the origin (0,0,0), the coordinates of the driver's position point A are (0,–(R+w1+w2),h); at the same time, taking the viewing plane as the reference plane, the visible area volume of the roadside landscape at point A is:

[0045]

[0046] In the formula,

[0047] V A : The visible volume of the roadside landscape at point A, in m 3 ;

[0048] α: horizontal viewing angle, unit: °;

[0049] α1: the viewing angle not blocked by the central dividing strip, unit: °;

[0050] L: sight distance, which varies with speed. The sight distance L here refers to the sight distance depth, which is divided into the front sight distance L1, the sight distance concentration point (L1+L2), and the sight distance depth (L1+L2+L3), in meters;

[0051] β: vertical viewing angle, unit: °;

[0052] β1: the upper vertical angle of the viewing plane, unit: °;

[0053] β2: The vertical angle of the visual plane, that is, the vertical angle not blocked by the visible distance in front of the vehicle, unit: °;

[0054] h: visual height, 1.2m for cars and 2.0m for trucks, unit: m;

[0055] R0: The radius of the highway curve, simulated by the minimum radius of the circular curve, unit: m;

[0056] R: The curve radius of the highway roadbed edge line, in m;

[0057] w1: the width of the lane edge from the inner curved roadbed edge to the outer curved median edge, in m;

[0058] w2: width from the outer edge of the outer curve median lane to the coordinate position of the car, in meters;

[0059] 2) The roadside landscape visual field occlusion space model at the starting point (point A)

[0060] like Figure 3 As shown in the figure, assuming that the occluder (the largest cross-section projected into the visible area is a rectangle) has a width of D and a height of H, and the relative coordinates of one point of the occluder are (x z ,y z ,z z ), the relative coordinates of the other three points of the occluder are (x z ,y z –D,z z ), (x z ,y z –D, z z +H), (x z ,y z ,z z +H), where z z =0m,y z for:

[0061]

[0062] In the formula,

[0063] R: The curve radius of the highway roadbed edge line, in m;

[0064] w1: the width of the lane edge from the inner curved roadbed edge to the outer curved median edge, in m;

[0065] w2: width from the outer edge of the outer curve median lane to the coordinate position of the car, in meters;

[0066] x z : X coordinate value of the occluder, in meters.

[0067] The occlusion volume of point A is calculated by the difference between two parts, namely, the large triangular pyramid V1 with an approximately rectangular bottom surface and the small triangular pyramid V2 with a rectangular bottom area.

[0068] ① The volume V1 of a large triangular pyramid with a rectangular bottom is calculated using the formula

[0069] From the triangle ratio relationship, we get:

[0070]

[0071] In the formula,

[0072] H s The height of the obstruction is projected onto the two sides of the bottom surface of the rectangular shape at the end of the viewing distance L, in meters.

[0073] H: height of the obstruction, in m;

[0074] L: sight distance, which varies with speed. The sight distance L here refers to the sight distance depth, which is divided into the front sight distance L1, the sight distance concentration point (L1+L2), and the sight distance depth (L1+L2+L3), in meters;

[0075] x z : X coordinate value of the occluder, in meters.

[0076]

[0077] In the formula,

[0078] D s The width of the obstruction is projected onto the two sides of the bottom surface of the rectangular shape at the end of the viewing distance L, in meters.

[0079] D: width of the obstruction, in m;

[0080] L: sight distance, which varies with speed. The sight distance L here refers to the sight distance depth, which is divided into the front sight distance L1, the sight distance concentration point (L1+L2), and the sight distance depth (L1+L2+L3), in meters;

[0081] x z : X coordinate value of the occluder, in meters.

[0082]

[0083] Where:

[0084] H s The height of the obstruction is projected onto the two sides of the bottom surface of the rectangular shape at the end of the viewing distance L, in meters.

[0085] H: height of the obstruction, in m;

[0086] D s The width of the obstruction is projected onto the two sides of the bottom surface of the rectangular shape at the end of the viewing distance L, in meters.

[0087] D: width of the obstruction, in m;

[0088] L: sight distance, which varies with speed. The sight distance L here refers to the sight distance depth, which is divided into the front sight distance L1, the sight distance concentration point (L1+L2), and the sight distance depth (L1+L2+L3), in meters;

[0089] x z : X coordinate value of the occluder, in meters.

[0090] ② The calculation formula for the volume V2 of a small triangular pyramid with a rectangular base area

[0091]

[0092] Therefore, the occlusion volume of point A is:

[0093]

[0094] Where:

[0095] H: height of the obstruction, in m;

[0096] D: width of the obstruction, in m;

[0097] L: sight distance, which varies with speed. The sight distance L here refers to the sight distance depth, which is divided into the front sight distance L1, the sight distance concentration point (L1+L2), and the sight distance depth (L1+L2+L3), in meters;

[0098] x z : X coordinate value of the occluder, in meters.

[0099] Therefore, the occlusion ratio of point A is:

[0100]

[0101] 3) The roadside landscape visual field occlusion spatial model when the vehicle travels to any point (point B)

[0102] When a vehicle moves from point A to point B, that is, at t i The obstructed volume of the visible area at point B at time is as follows Figure 4 shown.

[0103] When the driver travels from point A to point B, the arc length of the travel distance is L a for:

[0104]

[0105] In the formula,

[0106] v: vehicle speed, in km / h.

[0107] R: The curve radius of the highway roadbed edge line, in m;

[0108] t i : The travel time of a vehicle from point A to point B, in seconds.

[0109] w1: the width of the lane edge from the inner curved roadbed edge to the outer curved median edge, in m;

[0110] w2: width from the outer edge of the outer curve median lane to the coordinate position of the car, in meters;

[0111] δ: driving angle

[0112] Thus we can get:

[0113]

[0114] In the formula,

[0115] v: vehicle speed, in km / h.

[0116] R: The curve radius of the highway roadbed edge line, in m;

[0117] t i : The travel time of a vehicle from point A to point B, in seconds.

[0118] w1: the width of the lane edge from the inner curved roadbed edge to the outer curved median edge, in m;

[0119] w2: width from the outer edge of the outer curve median lane to the coordinate position of the car, in meters;

[0120] δ: driving angle

[0121] Then, the coordinates of point B are:

[0122]

[0123] In the formula,

[0124] v: vehicle speed, in km / h.

[0125] t i : The travel time of a vehicle from point A to point B, in seconds.

[0126] R: The curve radius of the highway roadbed edge line, in m;

[0127] w1: the width of the lane edge from the inner curved roadbed edge to the outer curved median edge, in m;

[0128] w2: width from the outer edge of the outer curve median lane to the coordinate position of the car, in meters;

[0129] δ: driving angle

[0130] Through trigonometric conversion, the coordinates of point B are simplified to:

[0131]

[0132] In the formula,

[0133] v: vehicle speed, in km / h.

[0134] R: The curve radius of the highway roadbed edge line, in m;

[0135] t i : The travel time of a vehicle from point A to point B, in seconds.

[0136] w1: the width of the lane edge from the inner curved roadbed edge to the outer curved median edge, in m;

[0137] w2: width from the outer edge of the outer curve median lane to the coordinate position of the car, in meters;

[0138] δ: driving angle

[0139]

[0140] In the formula,

[0141] v: vehicle speed, in km / h.

[0142] R: The curve radius of the highway roadbed edge line, in m;

[0143] t i : The travel time of a vehicle from point A to point B, in seconds.

[0144] w1: the width of the lane edge from the inner curved roadbed edge to the outer curved median edge, in m;

[0145] w2: width from the outer edge of the outer curve median lane to the coordinate position of the car, in meters;

[0146] δ: driving angle

[0147] H: height of the obstruction, in m;

[0148] D: width of the obstruction, in m;

[0149] L: sight distance, which varies with speed. The sight distance L here refers to the sight distance depth, which is divided into the front sight distance L1, the sight distance concentration point (L1+L2), and the sight distance depth (L1+L2+L3), in meters;

[0150] x z : X coordinate value of the occluder, in meters.

[0151] Therefore, the occlusion ratio of point B is:

[0152]

[0153] (4) Dynamic occlusion judgment model for the visual field of highway curved roadside landscape:

[0154] As for the width D and height H of the obstruction, during the movement of the vehicle, since the obstruction to the driver and the volume of the obstruction change, they are associated with the vehicle's driving speed, the circular curve radius of the curve, and the coordinates of the vehicle's initial point A, and they change continuously.

[0155] The D value of the occluder change is recorded as D j , D j The value can be determined and obtained by calculating the intersection of the driver's line of sight and the line segment of the occluder in the top view; the H value of the occluder change is recorded as H j , H j The value can be determined and obtained by calculating the intersection of the driver's line of sight and the line segment of the obstruction in the direct view.

[0156] 1)D j Value calculation and occlusion judgment

[0157] like Figure 5 As shown in the figure, assume that the vehicle drives to the point B (x0, y0) of the curve, and the top view of the occluder is equivalent to a line segment, whose two end points are D1 (x1, y1) and D2 (x2, y2). The coordinates of D1 and D2 are the spatial coordinates assumed by the occluder, that is, D1 (x z ,y z ,z z ) and D2(x z ,y z –D,z z ), then the occlusion width D j The intersection point J(x j ,y j )get.

[0158] ① The equation of the straight line through point B is BJ. From the geometric relationship, we know that:

[0159]

[0160] In the formula,

[0161] v: vehicle speed, in km / h.

[0162] t i : The travel time of a vehicle from point A to point B, in seconds.

[0163] R: The curve radius of the highway roadbed edge line, in m;

[0164] w1: the width of the lane edge from the inner curved roadbed edge to the outer curved median edge, in m;

[0165] w2: width from the outer edge of the outer curve median lane to the coordinate position of the car, in meters;

[0166] α: horizontal viewing angle, unit: °;

[0167] δ: driving angle, unit: °;

[0168] θ: The intersection angle between the straight line BJ and the X-axis, unit: °;

[0169] k=tan(-θ) (1-16)

[0170] In the formula,

[0171] θ: The intersection angle between the straight line BJ and the X-axis, unit: °;

[0172] Then, the ray equation through point B is:

[0173] y=k(x-x0)+y0 (1-17)

[0174] ②The equation of line segment D1D2 is:

[0175]

[0176] ③Find the intersection point J

[0177] By combining equations (1-17) and (1-18) and the coordinate formula of point B, we can find the intersection point J(x j ,y j ) is:

[0178]

[0179] In the formula,

[0180] v: vehicle speed, in km / h.

[0181] t i : The travel time of a vehicle from point A to point B, in seconds.

[0182] R: The curve radius of the highway roadbed edge line, in m;

[0183] w1: the width of the lane edge from the inner curved roadbed edge to the outer curved median edge, in m;

[0184] w2: width from the outer edge of the outer curve median lane to the coordinate position of the car, in meters;

[0185] α: horizontal viewing angle, unit: °;

[0186] x z : X coordinate value of the occluder, in meters.

[0187] ④Make the following judgments:

[0188] I) If y j > y1 and y j < y2, it is partially occluded, and D j = y j – y1. From the Figure 5 shown coordinate system and the actual roadside landscape, it can be seen that the D1 and D2 coordinates are both in the fourth quadrant, and the signs of the Y-axis coordinate values are the same.

[0189] II) If y j ≤ y1, it is unoccluded, and at this time D j = 0.

[0190] III) If y j ≥ y2, it is fully occluded, and at this time D j = y2 – y1.

[0191] The above are the calculation steps of the D j value. Substituting it into Equation (1-13) can obtain the occlusion volume when the vehicle travels to a certain point.

[0192] 2) Calculation of the H j value and occlusion judgment

[0193] As Figure 6 shown, assume that the vehicle travels to the point B(x0, h) on the curve, and the orthographic view of the occluder is equivalent to a line segment, and its two endpoints are H1(x1, H) and H2(x2, 0). The occlusion width H can be obtained by finding the intersection point J(x j , z j ).

[0194] ① According to geometric relationships, the slope of the ray passing through point B is:

[0195] k = tan(β1) (1-20)

[0196] where

[0197] β1: the upper vertical viewing angle of the viewing plane, unit °;

[0198] Then, the equation of the ray passing through point B is:

[0199] z = k(x - x0) + h (1-21)

[0200] where

[0201] h: the viewing height, 1.2 m for a car and 2.0 m for a truck, unit m;

[0202] ② The equation of the line segment H1H2 is:

[0203]

[0204] ③Find the intersection point J

[0205] By联立solving the equations of Formula (1-21) and Formula (1-22), and the coordinate formula of point B, the intersection point J(x j , z j ) is as follows:

[0206]

[0207] Wherein,

[0208] v: Vehicle driving speed, unit km / h.

[0209] t i : Driving time of the vehicle from point A to point B, unit s.

[0210] R: Radius of the curve of the highway subgrade edge line, unit m;

[0211] w1: Width from the inner subgrade edge to the edge lane line of the outer middle strip, unit m;

[0212] w2: Width from the outer middle strip outer edge lane line to the coordinate position of the vehicle, unit m;

[0213] β1: Upward vertical viewing angle of the viewing plane, unit °;

[0214] h: Viewing height, 1.2 m for cars and 2.0 m for trucks, unit m;

[0215] x z : X coordinate value of the obstacle, unit m.

[0216] ④Make the following judgments:

[0217] I) If z j ≥H, the occlusion height is H. From the coordinate system shown in Figure 6 and the actual roadside landscape, it can be seen that the H1 and H2 coordinates are both in the first quadrant and the signs of the Y-axis coordinate values are the same.

[0218] II) If z j <H, the occlusion height is z j .

[0219] The above are the calculation steps of the H j value. Substituting it into Formula (1-13) can obtain the occlusion volume when the vehicle travels to a certain point position.

[0220] As an optimization of the technical solution, the above is the roadside landscape of the highway curve.

[0221] Compared with the prior art, the advantages and beneficial effects of the present invention are:

[0222] (1) The model of the present invention fully considers the influence of factors such as curves, vehicles, and roadside plants. The established visual domain model is a dynamic occlusion space model, which can more accurately describe the dynamic occlusion of the visual domain of the curved roadside landscape. The model is used to perform calculations and analysis on the Hunan section of the Beijing-Hong Kong-Macao Expressway, and the results verify the correctness and effectiveness of the model.

[0223] (2) The calculation method of the present invention can calculate the dynamic occlusion space of the roadside landscape with different radii on each curved road section of the expressway, and the relationship between the driving speed and the dynamic occlusion of the visual domain. The faster the driving speed, the faster the dynamic occlusion of the visual domain changes. Based on this, it can provide a design basis for the setting of the curved roadside landscape, plant planting, and highway land acquisition scope of the expressway. It is also suitable for the planning, design, and safety management of the curved roadside landscape of the expressway, and provides a reference for effectively solving the problem of dynamic occlusion of the visual domain of the curved roadside landscape of the expressway. BRIEF DESCRIPTION OF THE DRAWINGS

[0224] Figure 1 It is a schematic diagram of the visible range of the curved roadside landscape of the present invention.

[0225] Figure 2 It is a schematic diagram of the visible area volume of the curved roadside landscape of the present invention.

[0226] Figure 3 The figure shows the volume of the obstructed visible area of ​​the curved roadside landscape (point A).

[0227] Figure 4 The obstructed volume of the visible area of ​​the curved roadside landscape is shown in Figure 1 (point B at time ti).

[0228] Figure 5 is the width of the obstruction D j Schematic diagram of value occlusion judgment.

[0229] Figure 6 is the height of the obstruction H j Schematic diagram of value occlusion judgment.

[0230] Figure 7 This is a schematic diagram of a typical standard cross section of the Hunan section of G4.

[0231] Figure 8 This is a simulation diagram of the changes in the obstruction volume and obstruction ratio of the roadside landscape by obstructions of different heights under the conditions of the same main line design speed, the same position, and consistent width.

[0232] Fig. 9 Simulation diagram of the changes in the blocked volume and blocking ratio of the roadside landscape by obstacles of different widths under the conditions of the same main line design speed, the same position and consistent height.

[0233] Fig.10 Simulation diagram of the changes in the obstruction volume and obstruction ratio of roadside landscape under the conditions of different main line design speeds, obstructions in the same position, and consistent width and height.

[0234] Fig.11 A simulation diagram of the changes in the obstruction volume and obstruction ratio of roadside landscape caused by obstructions of the same width and height but located at different positions. DETAILED DESCRIPTION

[0235] The present invention will be further described in detail below with reference to specific embodiments and accompanying drawings, but the present invention is not limited to its protection scope.

[0236] Example 1

[0237] The construction of a dynamic occlusion space model of the visible area of ​​the curved roadside landscape of a highway includes the following steps:

[0238] (1) Analyze the high-risk roadside landscape conditions of the curved road accident, and analyze the factors that dynamically block the visual area of ​​the curved roadside landscape from various aspects.

[0239] (2) Define the visible area of ​​the curved roadside landscape:

[0240] During the vehicle movement, the visible area of ​​the curved roadside landscape is as follows: Figure 1 As shown in the figure, it is the cone enclosed by the tangent line of the left side of the driver's visual height h to the central dividing strip, the right side field of vision and the depth of visibility. The obstruction of the visual domain of the curved roadside landscape means that under certain vehicle speed conditions, assuming that the driver's head does not move and only looks at the front of the highway, there are obstructions in the driver's visual domain, making it impossible for the driver to see the roadside landscape from the right side of the roadbed or the roadside landscape is partially obstructed, thus affecting the integrity of the roadside landscape.

[0241] (3) Construct a dynamic occlusion space model for the visual process of the highway curve roadside landscape:

[0242] 1) The volume calculation equation of the visible area of ​​the highway curve roadside landscape is:

[0243] like Figure 2 As shown in the figure, taking the center of the circular curve of the highway curve as the origin (0,0,0), the coordinates of the driver's position point A are (0,–(R+w1+w2),h); at the same time, taking the viewing plane as the reference plane, the visible area volume of the roadside landscape at point A is:

[0244]

[0245] In the formula,

[0246] V A: The visible volume of the roadside landscape at point A, in m 3 ;

[0247] α: horizontal viewing angle, unit: °;

[0248] α1: the viewing angle not blocked by the central dividing strip, unit: °;

[0249] L: sight distance, which varies with speed. The sight distance L here refers to the sight distance depth, which is divided into the front sight distance L1, the sight distance concentration point (L1+L2), and the sight distance depth (L1+L2+L3), in meters;

[0250] β: vertical viewing angle, unit: °;

[0251] β1: the upper vertical angle of the viewing plane, unit: °;

[0252] β2: The vertical angle of the visual plane, that is, the vertical angle not blocked by the visible distance in front of the vehicle, unit: °;

[0253] h: visual height, 1.2m for cars and 2.0m for trucks, unit: m;

[0254] R0: The radius of the highway curve, simulated by the minimum radius of the circular curve, unit: m;

[0255] R: The curve radius of the highway roadbed edge line, in m;

[0256] w1: the width of the lane edge from the inner curved roadbed edge to the outer curved median edge, in m;

[0257] w2: width from the outer edge of the outer curve median lane to the coordinate position of the car, in meters;

[0258] 2) The roadside landscape visual field occlusion space model at the starting point (point A)

[0259] like Figure 3 As shown in the figure, assuming that the occluder (the largest cross-section projected into the visible area is a rectangle) has a width of D and a height of H, and the relative coordinates of one point of the occluder are (x z ,y z ,z z ), the relative coordinates of the other three points of the occluder are (x z ,y z –D,z z ), (x z ,y z –D, z z +H), (x z ,y z ,z z +H), where z z =0m,y z for:

[0260]

[0261] In the formula,

[0262] R: The curve radius of the highway roadbed edge line, in m;

[0263] w1: the width of the lane edge from the inner curved roadbed edge to the outer curved median edge, in m;

[0264] w2: width from the outer edge of the outer curve median lane to the coordinate position of the car, in meters;

[0265] x z : X coordinate value of the occluder, in meters.

[0266] The occlusion volume of point A is calculated by the difference between two parts, namely, the large triangular pyramid V1 with an approximately rectangular bottom surface and the small triangular pyramid V2 with a rectangular bottom area.

[0267] ① The volume V1 of a large triangular pyramid with a rectangular bottom is calculated using the formula

[0268] From the triangle ratio relationship, we get:

[0269]

[0270] In the formula,

[0271] H s The height of the obstruction is projected onto the two sides of the bottom surface of the rectangular shape at the end of the viewing distance L, in meters.

[0272] H: height of the obstruction, in m;

[0273] L: sight distance, which varies with speed. The sight distance L here refers to the sight distance depth, which is divided into the front sight distance L1, the sight distance concentration point (L1+L2), and the sight distance depth (L1+L2+L3), in meters;

[0274] x z : X coordinate value of the occluder, in meters.

[0275]

[0276] In the formula,

[0277] D s The width of the obstruction is projected onto the two sides of the bottom surface of the rectangular shape at the end of the viewing distance L, in meters.

[0278] D: width of the obstruction, in m;

[0279] L: sight distance, which varies with speed. The sight distance L here refers to the sight distance depth, which is divided into the front sight distance L1, the sight distance concentration point (L1+L2), and the sight distance depth (L1+L2+L3), in meters;

[0280] x z : X coordinate value of the occluder, in meters.

[0281]

[0282] In the formula,

[0283] H s The height of the obstruction is projected onto the two sides of the bottom surface of the rectangular shape at the end of the viewing distance L, in meters.

[0284] H: height of the obstruction, in m;

[0285] D s The width of the obstruction is projected onto the two sides of the bottom surface of the rectangular shape at the end of the viewing distance L, in meters.

[0286] D: width of the obstruction, in m;

[0287] L: sight distance, which varies with speed. The sight distance L here refers to the sight distance depth, which is divided into the front sight distance L1, the sight distance concentration point (L1+L2), and the sight distance depth (L1+L2+L3), in meters;

[0288] x z : X coordinate value of the occluder, in meters.

[0289] ② The calculation formula for the volume V2 of a small triangular pyramid with a rectangular base area

[0290]

[0291] Therefore, the occlusion volume of point A is:

[0292]

[0293] In the formula,

[0294] H: height of the obstruction, in m;

[0295] D: width of the obstruction, in m;

[0296] L: sight distance, which varies with speed. The sight distance L here refers to the sight distance depth, which is divided into the front sight distance L1, the sight distance concentration point (L1+L2), and the sight distance depth (L1+L2+L3), in meters;

[0297] x z : X coordinate value of the occluder, in meters.

[0298] Therefore, the occlusion ratio of point A is:

[0299]

[0300] 3) The roadside landscape visual field occlusion spatial model when the vehicle travels to any point (point B)

[0301] When a vehicle moves from point A to point B, that is, at t i The obstructed volume of the visible area at point B at time is as follows Figure 4 shown.

[0302] When the driver travels from point A to point B, the arc length of the travel distance is L a for:

[0303]

[0304] In the formula,

[0305] v: vehicle speed, in km / h.

[0306] R: The curve radius of the highway roadbed edge line, in m;

[0307] t i : The travel time of a vehicle from point A to point B, in seconds.

[0308] w1: the width of the lane edge from the inner curved roadbed edge to the outer curved median edge, in m;

[0309] w2: width from the outer edge of the outer curve median lane to the coordinate position of the car, in meters;

[0310] δ: driving angle

[0311] Thus we can get:

[0312]

[0313] In the formula,

[0314] v: vehicle speed, in km / h.

[0315] R: The curve radius of the highway roadbed edge line, in m;

[0316] t i : The travel time of a vehicle from point A to point B, in seconds.

[0317] w1: the width of the lane edge from the inner curved roadbed edge to the outer curved median edge, in m;

[0318] w2: width from the outer edge of the outer curve median lane to the coordinate position of the car, in meters;

[0319] δ: driving angle

[0320] Then, the coordinates of point B are:

[0321]

[0322] In the formula,

[0323] v: vehicle speed, in km / h.

[0324] t i : The travel time of a vehicle from point A to point B, in seconds.

[0325] R: The curve radius of the highway roadbed edge line, in m;

[0326] w1: the width of the lane edge from the inner curved roadbed edge to the outer curved median edge, in m;

[0327] w2: width from the outer edge of the outer curve median lane to the coordinate position of the car, in meters;

[0328] δ: Driving angle

[0329] Through trigonometric conversion, the coordinates of point B are simplified to:

[0330]

[0331] In the formula,

[0332] v: vehicle speed, in km / h.

[0333] R: The curve radius of the highway roadbed edge line, in m;

[0334] t i : The travel time of a vehicle from point A to point B, in seconds.

[0335] w1: the width of the lane edge from the inner curved roadbed edge to the outer curved median edge, in m;

[0336] w2: width from the outer edge of the outer curve median lane to the coordinate position of the car, in meters;

[0337] δ: driving angle

[0338]

[0339] In the formula,

[0340] v: vehicle speed, in km / h.

[0341] R: The curve radius of the highway roadbed edge line, in m;

[0342] t i : The travel time of a vehicle from point A to point B, in seconds.

[0343] w1: the width of the lane edge from the inner curved roadbed edge to the outer curved median edge, in m;

[0344] w2: width from the outer edge of the outer curve median lane to the coordinate position of the car, in meters;

[0345] δ: driving angle

[0346] H: height of the obstruction, in m;

[0347] D: width of the obstruction, in m;

[0348] L: sight distance, which varies with speed. The sight distance L here refers to the sight distance depth, which is divided into the front sight distance L1, the sight distance concentration point (L1+L2), and the sight distance depth (L1+L2+L3), in meters;

[0349] x z : X coordinate value of the occluder, in meters.

[0350] Therefore, the occlusion ratio of point B is:

[0351]

[0352] (4) Dynamic occlusion judgment model for the visual field of highway curved roadside landscape:

[0353] As for the width D and height H of the obstruction, during the movement of the vehicle, since the obstruction to the driver and the volume of the obstruction change, they are associated with the vehicle's driving speed, the circular curve radius of the curve, and the coordinates of the vehicle's initial point A, and they change continuously.

[0354] The D value of the occluder change is recorded as D j , D j The value can be determined and obtained by calculating the intersection of the driver's line of sight and the line segment of the occluder in the top view; the H value of the occluder change is recorded as H j , H j The value can be determined and obtained by calculating the intersection of the driver's line of sight and the line segment of the obstruction in the direct view.

[0355] 1)D j Value calculation and occlusion judgment

[0356] like Figure 5As shown in the figure, assume that the vehicle drives to the point B (x0, y0) of the curve, and the top view of the occluder is equivalent to a line segment, whose two end points are D1 (x1, y1) and D2 (x2, y2). The coordinates of D1 and D2 are the spatial coordinates assumed by the occluder, that is, D1 (x z ,y z ,z z ) and D2(x z ,y z –D,z z ), then the occlusion width D j The intersection point J(x j ,y j )get.

[0357] ① The equation of the straight line through point B is BJ. From the geometric relationship, we know that:

[0358]

[0359] In the formula,

[0360] v: vehicle speed, in km / h.

[0361] t i : The travel time of a vehicle from point A to point B, in seconds.

[0362] R: The curve radius of the highway roadbed edge line, in m;

[0363] w1: the width of the lane edge from the inner curved roadbed edge to the outer curved median edge, in m;

[0364] w2: width from the outer edge of the outer curve median lane to the coordinate position of the car, in meters;

[0365] α: horizontal viewing angle, unit: °;

[0366] δ: driving angle, unit: °;

[0367] θ: The intersection angle between the straight line BJ and the X-axis, unit: °;

[0368] k=tan(-θ) (1-16)

[0369] In the formula,

[0370] θ: The intersection angle between the straight line BJ and the X-axis, unit: °;

[0371] Then, the ray equation through point B is:

[0372] y=k(x-x0)+y0 (1-17)

[0373] ②The equation of line segment D1D2 is:

[0374]

[0375] ③Find the intersection point J

[0376] By solving the equations of Equation (1-17) and Equation (1-18), and the coordinate formula of point B, the coordinates of the intersection point J(x j , y j ) are as follows:

[0377]

[0378] Where,

[0379] v: Vehicle driving speed, unit km / h.

[0380] t i : Driving time of the vehicle from point A to point B, unit s.

[0381] R: Radius of the curve of the highway subgrade edge line, unit m;

[0382] w1: Width from the inner subgrade edge to the outer middle strip edge lane line, unit m;

[0383] w2: Width from the outer middle strip outer edge lane line to the vehicle's coordinate position, unit m;

[0384] α: Horizontal viewing angle, unit °;

[0385] x z : X coordinate value of the obstacle, unit m.

[0386] ④Make the following judgments:

[0387] I) If y j > y1 and y j < y2, it is partial occlusion, and D j = y j – y1. From the Figure 5 shown coordinate system and the actual roadside landscape, it can be seen that the D1 and D2 coordinates are both in the fourth quadrant and have the same sign for the Y-axis coordinate value.

[0388] II) If y j ≤ y1, it is non-occlusion, and at this time D j = 0.

[0389] III) If y j ≥ y2, it is full occlusion, and at this time D j = y2 – y1.

[0390] The above is for D jThe calculation steps of the value can be substituted into formula (1-13) to obtain the occlusion volume when the vehicle travels to a certain point.

[0391] 2) H j Value calculation and occlusion judgment

[0392] like Figure 6 As shown in the figure, assuming that the vehicle drives to the point B (x0, h) of the curve, and the straight view of the occluder is equivalent to a line segment, whose two end points are H1 (x1, H) and H2 (x2, 0), the occlusion width H can be obtained by finding the intersection point J (x j ,z j )get.

[0393] ① The equation of the ray passing through point B is known from geometric relationships, and its slope is:

[0394] k=tan(β1) (1-20)

[0395] In the formula,

[0396] β1: the upper vertical angle of the viewing plane, unit: °;

[0397] Then, the ray equation through point B is:

[0398] z=k(x-x0)+h (1-21)

[0399] In the formula,

[0400] h: visual height, 1.2m for cars and 2.0m for trucks, unit: m;

[0401] ②The equation of line segment H1H2 is:

[0402]

[0403] ③Find the intersection point J

[0404] By combining equations (1-21) and (1-22) and the coordinate formula of point B, we can find the intersection point J(x j ,z j )for:

[0405]

[0406] In the formula,

[0407] v: vehicle speed, in km / h.

[0408] t i : The travel time of a vehicle from point A to point B, in seconds.

[0409] R: The curve radius of the highway roadbed edge line, in m;

[0410] w1: The width from the inner-bent roadbed edge to the lane centerline of the outer-bent median edge, unit: m;

[0411] w2: The width from the outer edge of the outer-bent median to the vehicle's coordinate position, unit: m;

[0412] β1: The upward vertical viewing angle of the viewing plane, unit: °;

[0413] h: The viewing height, 1.2 m for cars and 2.0 m for trucks, unit: m;

[0414] x z : The X coordinate value of the obstacle, unit: m.

[0415] ④ Make the following judgments:

[0416] I) If z j ≥H, then the occlusion height is H. From the Figure 6 shown coordinate system and the actual roadside landscape, it can be seen that the H1 and H2 coordinates are both in the first quadrant and have the same sign for the Y-axis coordinate values.

[0417] II) If z j <H, then the occlusion height is z j .

[0418] The above are the calculation steps for the H j value. Substituting into Equation (1-13), the occlusion volume when the vehicle travels to a certain point can be obtained.

[0419] (5) Verify the correctness and effectiveness of the model, including:

[0420] ① Collect relevant data on the Hunan section of the Beijing-Hong Kong-Macao Expressway:

[0421] The overall standard cross-section layout of the Hunan section of the Beijing-Hong Kong-Macao Expressway is as Figure 7 shown, with four lanes in both directions, a roadbed width of 28 m, and a symmetrical layout. Among them, the half-section is: 1.5 m central divider + 0.75 m left shoulder strip + 2×3.75 m driving lanes + 3.5 m hard shoulder + 0.75 m earthen shoulder.

[0422] ② Check relevant parameters

[0423] The design speed v and the radius R of the circular curve of the bend are taken according to the regulations in the "Highway Route Design Code" (JTG D20-2017), as shown in Table 1. The horizontal viewing angle α and the vertical viewing angle β are taken according to Table 1, and the upward vertical viewing angle β1 of the vertical view is taken as 30°. The visible distance L1 in front of the vehicle, the concentrated point L2 of the visible distance, and the depth L3 of the visible distance are taken according to Table 1, and the viewing distance L is taken according to the depth of the visible distance. The viewing height h is taken as 1.2 m for cars.

[0424] Table 1 Values ​​of v, R, α, β, and L

[0425]

[0426] The value of the height H of the obstruction: The most frequent obstruction on the roadside is the roadside plants, followed by the road cut slope. Among them, the roadside plants are divided into trees (large trees above 31m, large trees 21-30m, medium trees 11-20m, small trees 6-10m), shrubs (large shrubs 3-6m, small shrubs 1-3m) and open vegetation (ground cover, flowers and grass below 1m); according to the road cut slopes of the Hunan section of G4 and G60, their heights are divided into high slopes (above 10m), medium slopes (5-10m) and low slopes (below 5m). Other obstructions, such as the height of the sound barrier is generally 2-3.5m, the height of the guardrail is 1.2-1.8m, the height of the monitoring equipment is 6m, and the height of the signboard is generally 3.5-5.5m. Since the plants planted on the side of the highway are mainly small trees and shrubs, and high slopes are avoided as much as possible in the design due to the large amount of excavation and serious disasters such as landslides, the height H of the shield is selected as 3m, 5m, 10m, 15m, and 20m as the calculation value.

[0427] The value of the width D of the obstruction: According to the highway land scope confirmed in the "Highway Engineering Technical Standard" (JTG B01-2014), it is stipulated that it is outside the outer edge of the drainage ditch on both sides of the embankment, outside the slope foot of the embankment (slope protection road) when there is no drainage ditch, or outside the outer edge of the intercepting ditch on the top of the cutting slope, and outside the slope top when there is no intercepting ditch, and the land within the range of not less than 1m; in sections with conditions, the land within the range of not less than 3m for expressways and first-class highways and not less than 2m for second-class highways. In the design of the Hunan section of G4, its land use scope is 2 to 3m outside the drainage ditch at the foot of the roadbed fill slope, and 5m outside the top of the excavation slope; together with the slope within the highway boundary, the distance from the road surface boundary to the road boundary marker is about 5 to 30m. Therefore, the present invention verifies and selects the width D of the obstruction as 3m, 5m, 10m, 20m, and 30m as the calculated value.

[0428] The occluder position value: The occluder position is determined by x z The decision is mainly based on L2 (visibility focus point) and L3 (visibility depth), see the values ​​in Table 1. When the design speed is 120km / h, select x z is 300m and 700m; when the design speed is 100km / h, select x z 200m and 400m; when the design speed is 80km / h, select x z 200m and 400m; When the design speed is 60km / h, select x z 100m and 300m.

[0429] ③Verification of dynamic occlusion spatial model of the visual domain of the curved roadside landscape in the Hunan section of the Beijing-Hong Kong-Macao Expressway:

[0430] Through MATLAB modeling, the relevant parameters are substituted into the dynamic occlusion space model of the highway curve roadside landscape visual domain:

[0431]

[0432] For the same main line design speed, the width of the shield at the same position is consistent but the height is inconsistent (see Figure 8 for the change pattern); for the same main line design speed, the height of the shield at the same position is consistent but the width is inconsistent (see Figure 9 for the change pattern). Fig. 9 ); Different main line design speeds, when the width and height of the obstruction at the same position are consistent (see the change diagram for the law Fig.10 ); When the occluders with the same width and height are located at different positions (see the law of the change diagram Fig.11 ) and other situations are simulated, and the occlusion judgment model is used to verify the results. The rules presented are as follows: for the changes in occlusion volume and occlusion ratio, the larger the width of the occlusion and the higher the height, the longer the occlusion time, and the occlusion process shows an inverted "V" shape change rule; it takes 6 to 8 seconds from the occurrence of occlusion to the peak values ​​of occlusion volume and occlusion ratio.

[0433] from Figure 8 It can be seen that the smaller the width of the occluder, the later the peak value of the occluded volume and occluded ratio appears, and the larger the width, the larger the occluded volume and occluded ratio. This shows that the influence of the occluder width value is greater than the height value. Figure 8 (d) It can be calculated that when the width of the obstruction (D=30 m) is relatively wide, the obstruction ratio reaches 50% when the height is about 16.9 m, and the obstruction is serious.

[0434] from Fig. 9 It can be seen that the lower the height of the occluder, the later the peak of the occlusion volume and occlusion ratio appears, and the higher the height, the larger the occlusion volume and occlusion ratio. This shows that the height of the occluder has a certain influence on the occlusion of the visual domain, but the influence is not as obvious as the width of the occluder, and it is also affected by the distance between the occluders. Fig. 9 (d) It can be calculated that when the height of the obstruction (H = 20m) is high, the obstruction ratio reaches 50% when the width is 22.8m, and the obstruction is serious.

[0435] from Fig.10It can be seen that the faster the driving speed, the larger the radius of the curve, that is, the smoother the curve, and the larger the volume of the roadside landscape visible area blocked by the same size of the obstruction, the larger the obstruction ratio; the smaller the speed, the smaller the obstruction volume, and the smaller the obstruction ratio. The shorter the time it is affected by the obstruction, and the slower the driving speed, the longer the time it is affected by the obstruction. The earlier the peak of the obstruction volume appears. The slower the driving speed, the shorter the time from the peak of the obstruction volume and the obstruction ratio to the zero obstruction, that is, the faster the driving speed, the greater the impact on the driver for obstructions of low height.

[0436] from Fig.11 It can be seen that when the obstruction is far away from the driver, that is, when the obstruction is located within the visual range concentration point (L2), the obstruction volume and obstruction ratio are larger than when the obstruction is located outside the visual range concentration point (L3), and the time for the obstruction ratio to reach the peak is shorter. This shows that the obstruction effect of the obstruction within the visual range concentration point is large, that is, the obstruction effect of the obstruction within the range close to the roadside landscape is large. The faster the driving speed, the larger the obstruction volume and obstruction ratio of the obstruction of the same size at the same position, the shorter the obstruction effect time, and the earlier the peak time of the obstruction volume and obstruction ratio. This shows that the faster the speed, the greater the impact of the roadside obstruction on the driver's roadside landscape.

Claims

1. A method for constructing a dynamic occlusion spatial model of the visible area of ​​a highway curved roadside landscape, characterized in that: The construction of the model includes the following steps: (1) Analyze the high-risk roadside landscape conditions of the curved road accident, and analyze the factors that dynamically block the visual domain of the curved roadside landscape from various aspects; (2) Define the visible area of ​​the curved roadside landscape: During vehicle movement, the visible area of ​​the curved roadside landscape is the cone enclosed by the tangent line of the driver's visual height h to the central dividing strip on the left side and the visual range and visibility depth on the right side. The obstruction of the curved roadside landscape visual area means that under certain vehicle speed conditions, assuming that the driver's head does not move and only looks at the front of the highway, there are obstructions in the driver's visual area, making it impossible for the driver to see the roadside landscape from the right side of the roadbed or the roadside landscape is partially obstructed, thus affecting the integrity of the roadside landscape. (3) Construct a dynamic occlusion space model for the visual process of the highway curve roadside landscape: 1) The volume calculation equation of the visible area of ​​the highway curve roadside landscape is: Taking the center of the circular curve of the highway as the origin (0,0,0), the coordinates of point A where the driver is located are (0,-(R+w1+w2),h); taking the viewing plane as the reference plane, the visible volume of the roadside landscape at point A is: Where: V A : The visible volume of the roadside landscape at point A, in m 3 ; α: horizontal viewing angle, varies with speed, unit: °; α1: the viewing angle not blocked by the central dividing strip, unit: °; L: sight distance, which varies with speed. The sight distance L here refers to the sight distance depth, which is divided into the front sight distance L1, the sight distance concentration point (L1+L2), and the sight distance depth (L1+L2+L3), in meters; β: vertical viewing angle, which is the sum of β1 and β2, unit: °; β1: the upper vertical angle of the viewing plane, unit: °; β2: The vertical angle of the visual plane, that is, the vertical angle not blocked by the visible distance in front of the vehicle, unit: °; h: visual height, 1.2m for cars and 2.0m for trucks, unit: m; R0: The radius of the highway curve, simulated by the minimum radius of the circular curve, unit: m; R: The curve radius of the highway roadbed edge line, in m; w1: the width of the lane edge from the inner curved roadbed edge to the outer curved median edge, in m; w2: width from the outer edge of the outer curve median lane to the coordinate position of the car, in meters; 2) The roadside landscape visual field occlusion space model at the starting point (point A) Assume that the maximum cross-section of the occluder projected into the visible area is a rectangle with a width of D and a height of H. The relative coordinates of one point of the occluder are (x z ,y z ,z z ), the relative coordinates of the other three points of the occluder are (x z ,y z -D,z z ), (x z ,y z -D,z z +H), (x z ,y z ,z z +H), where z z =0m,y z for: Where: x z : X coordinate value of the occluder, unit: m; The occlusion volume of point A is calculated by the difference between two parts, namely, the large triangular pyramid V1 with a nearly rectangular bottom surface and the small triangular pyramid V2 with a rectangular bottom area; ① The volume V1 of a large triangular pyramid with a rectangular bottom is calculated using the formula From the triangle ratio relationship, we get: Where: H s The height of the obstruction is projected onto the two sides of the bottom surface of the rectangular shape at the end of the viewing distance L, in meters. H: height of the obstruction, in m; L: sight distance, which varies with speed. The sight distance L here refers to the sight distance depth, which is divided into the front sight distance L1, the sight distance concentration point (L1+L2), and the sight distance depth (L1+L2+L3), in meters; Where: D s The width of the obstruction is projected onto the two sides of the bottom surface of the rectangular shape at the end of the viewing distance L, in meters. D: width of the obstruction, in m; ② The calculation formula for the volume V2 of a small triangular pyramid with a rectangular base area Therefore, the occlusion volume of point A is: Therefore, the occlusion ratio of point A is: 3) The roadside landscape visual field occlusion spatial model when the vehicle travels to any point (point B) When a vehicle moves from point A to point B, that is, at t i The visible area of ​​point B at time is blocked by volume; When the driver travels from point A to point B, the arc length of the travel distance is L a for: Where: δ: driving angle Thus we can get: Then, the coordinates of point B are: Through trigonometric conversion, the coordinates of point B are simplified to: Therefore, the occlusion ratio of point B is: v: vehicle speed, in km / h; t i : The driving time when the vehicle moves from point A to point B, unit: s; (4) Dynamic occlusion judgment model for the visual field of highway curved roadside landscape: As for the width D and height H of the obstruction, during the movement of the vehicle, since the obstruction and the volume of the obstruction to the driver are changing, they are associated with the vehicle's driving speed, the radius of the circular curve of the curve, and the coordinates of the vehicle's initial point A, and they are constantly changing; The D value of the occluder change is recorded as D j , D j The value can be determined and obtained by calculating the intersection of the driver's line of sight and the line segment of the occluder in the top view; the H value of the occluder change is recorded as H j , H j The value can be determined and obtained by calculating the intersection of the driver's line of sight and the line segment of the obstruction in the direct view; 1) D j Value calculation and occlusion judgment Assume that the vehicle drives to the point B (x0, y0) of the curve, and the top view of the occluder is equivalent to a line segment, whose two end points are D1 (x1, y1) and D2 (x2, y2). The coordinates of D1 and D2 are the spatial coordinates assumed by the occluder, that is, D1 (x z ,y z ,z z ) and D2(x z ,y z -D,z z ), then the occlusion width D j The intersection point J(x j ,y j )get; ① The equation of the straight line through point B is BJ. From the geometric relationship, we know that: Where: θ: The intersection angle between the straight line BJ and the X-axis, unit: °; k=tan(-θ) (1-16) Then, the ray equation through point B is: y=k(x-x0)+y0 (1-17) ②The equation of line segment D1D2 is: ③Find the intersection point J By combining equations (1-17) and (1-18) and the coordinate formula of point B, we can find the intersection point J(x j ,y j ) is: ④ Make the following judgment: I) If y j > y1 and y j < y2, it is partially occluded, and D j = y j - y1; From the coordinate system and the actual roadside landscape, it can be seen that the D1 and D2 coordinates are both in the fourth quadrant and have the same sign for the Y-axis coordinate values; II) If y j ≤y1, then there is no occlusion, and D j =0; III) If y j ≥y2, it is full occlusion, then D j =y2-y1; The above is D j The calculation steps of the value can be substituted into formula (1-13) to obtain the occlusion volume when the vehicle travels to a certain point; 2) H j Value calculation and occlusion judgment Assume that the vehicle travels to the point B(x0,h) of the curve, and the straight view of the occluder is equivalent to a line segment with two end points H1(x1,H) and H2(x2,0). The occlusion width H can be obtained by finding the intersection point J(x j ,z j )get; ① The equation of the ray passing through point B is known from geometric relationships, and its slope is: k=tan(β1) (1-20) Then, the ray equation through point B is: z=k(x-x0)+h (1-21) ②The equation of line segment H1H2 is: ③Find the intersection point J By combining equations (1-21) and (1-22) and the coordinate formula of point B, we can find the intersection point J(x j ,z j )for: ④ Make the following judgment: I) If z j ≥H, then the occlusion height is H; from the coordinate system and the actual roadside landscape, it can be seen that the coordinates of H1 and H2 are both located in the first quadrant, and the signs of the Y-axis coordinate values ​​are the same; II) If z j < H, then the occlusion height is z j ; The above is H j The calculation steps of the value can be substituted into formula (1-13) to obtain the occlusion volume when the vehicle travels to a certain point.

Images