Evaluation method for daytime visibility of road markings

Abstract

The present application discloses a method for evaluating the daytime visibility of road markings, a method for setting road markings, and a road. The method for evaluating the daytime visibility of road markings includes: determining a safe sight distance at a prescribed speed based on a prescribed speed on a road with road markings; determining a brightness contrast threshold of the road markings based on the safe sight distance and road marking characteristics according to a brightness contrast model in which the sight distance changes with brightness contrast; obtaining the brightness contrast of the road markings relative to the surrounding road surface; and determining the first daytime visibility of the road markings based on the obtained brightness contrast and the determined brightness contrast threshold. The daytime visibility technology for road markings provided in the embodiments of the present application can fully meet the driver's need for visual recognition of road markings for safe and comfortable driving on daytime roads.

Description

Technical Field

[0001] The present application relates to the field of highway traffic, specifically to a road marking setting technology, more specifically to a method for evaluating the daytime visibility of a road marking, and also to a road marking setting method and a road. Background Art

[0002] Traffic markings painted on the road are a traffic control facility that channels traffic, guides alignment, and ensures traffic safety. They can define lane boundaries, regulate and manage drivers' driving behavior, guide drivers' sight, indicate and warn of road conditions ahead, and clarify the right of way.

[0003] As demand for highway travel increases, road markings must also meet daytime visibility requirements to reduce potential driver risks. Reduced daytime road marking visibility reduces driver recognition efficiency, reducing the time drivers have to observe other road conditions. This reduces safe sight distance, making it difficult for drivers to detect road conditions in a timely manner, leading to traffic accidents and posing safety risks.

[0004] However, there is currently a lack of an evaluation method for the daytime visibility of road markings that can effectively meet drivers' visual needs for driving safety.

[0005] The content of this background technology description is only for facilitating understanding of the relevant technology in this field and is not regarded as an admission of the prior art. Summary of the Invention

[0006] Therefore, the embodiments of the present application hope to provide a method for evaluating the daytime visibility of highway traffic markings based on the driver's safety vision needs, thereby realizing the visibility evaluation of highway traffic markings based on meeting the driver's vision needs for safe driving during the day, and being able to selectively further process the markings based on the evaluation results.

[0007] In addition, the present application also hopes to provide a marking setting method and a road, wherein the markings set by the marking setting method or the markings on the road can fully meet the driver's visual requirements for highway traffic markings for safe driving during the day.

[0008] In a first aspect, a method for evaluating the visibility of a road marking during the day is provided, which may include:

[0009] determining a safe sight distance at a prescribed speed on a road with markings;

[0010] Determining a brightness contrast threshold of the marking based on the safe viewing distance and marking characteristics according to a brightness contrast model in which viewing distance varies with brightness contrast, the marking characteristics including marking color and / or width;

[0011] Obtain the brightness contrast of the markings relative to the surrounding road surface;

[0012] A first daytime visibility of the reticle is determined based on the acquired luminance contrast and the determined luminance contrast threshold.

[0013] Optionally, the method for evaluating road marking visibility during the day is characterized by further comprising:

[0014] Determining a diffuse reflection brightness coefficient threshold of the marking based on the safe viewing distance and the marking characteristics according to a diffuse reflection brightness coefficient model in which the viewing distance varies with the diffuse reflection brightness coefficient;

[0015] Obtaining the diffuse reflection brightness coefficient of the marking line;

[0016] The second daytime visibility of the marking line is further determined based on the acquired diffuse reflection brightness coefficient and the determined diffuse reflection brightness coefficient threshold.

[0017] Optionally, the brightness contrast model includes a plurality of different models based on different marking line features, and is shown in the following formula:

[0018] f i (x) = A i ln(x)+B i

[0019] Where f(x) represents the viewing distance, i refers to different models corresponding to different road marking characteristics, x represents the brightness contrast of the road marking relative to the surrounding road surface, and A and B are positive constants.

[0020] Optionally, the multiple models are shown as follows:

[0021] ① For the marking line with the first color and the first width:

[0022] f1(x)=22.967ln(x)+69.488

[0023] ②For the marking line with the first color and the second width:

[0024] f2(x)=20.810ln(x)+55.729

[0025] ③For the marking line with the second color and the first width:

[0026] f3(x)=20.290ln(x)+74.571

[0027] ④ For marking lines with a second color and a second width:

[0028] f4(x)=22.260ln(x)+59.528.

[0029] Optionally, the method for evaluating road marking visibility during the day may further include:

[0030] The brightness contrast model is constructed.

[0031] Optionally, constructing the brightness contrast model includes:

[0032] Acquiring first visual recognition data of a plurality of drivers recognizing road markings in at least one daytime brightness environment, the first visual recognition data including a plurality of different viewing distances corresponding to a plurality of different brightness contrasts under different road marking features;

[0033] The brightness contrast model is generated by fitting the first visual recognition data.

[0034] Optionally, obtaining first visual recognition data of a plurality of drivers visually recognizing a marking in at least one daytime brightness environment includes:

[0035] S1211: For each of the multiple marking colors and widths, provide multiple test markings with multiple different brightness contrasts;

[0036] S1212: Measuring lighting characteristics of one of a plurality of daytime brightness environments, where the lighting characteristics include color temperature and / or illuminance;

[0037] S1213: placing one of the plurality of test markings on the road as a marking to be tested or covering the remaining test markings except the marking to be tested;

[0038] S1214: Obtaining brightness values ​​of the marking to be measured and the surrounding road surface for determining brightness contrast;

[0039] S1215: One of the multiple drivers drives the vehicle slowly toward the test marking from a distance until the test marking appears as a horizontal line in the driver's field of view;

[0040] S1216: Obtaining the distance between the vehicle and the line to be measured when a horizontal line appears in the driver's field of view as the viewing distance corresponding to the brightness contrast of the line to be measured;

[0041] S1217: Repeat steps S1215 to S1216 for each driver until completion;

[0042] S1218: Repeat steps S1213 and S1217 for each test mark until completion;

[0043] S1219: For each daytime brightness environment, repeat steps S1212 to S1218 until the end.

[0044] Optionally, for each of the multiple reticle colors and widths, multiple test reticle colors with multiple brightness contrasts are provided, including:

[0045] The diffuse reflection brightness coefficients of the plurality of test marks are measured.

[0046] Optionally, the method for evaluating road marking visibility during the day may further include:

[0047] Construct the diffuse reflection brightness coefficient model.

[0048] Optionally, constructing the diffuse reflection brightness coefficient model includes:

[0049] Acquiring second visual recognition data of a plurality of drivers recognizing a road marking in at least one daytime brightness environment, the second visual recognition data including a plurality of different viewing distances corresponding to a plurality of different diffuse reflection brightness coefficients under different road marking characteristics;

[0050] The diffuse reflection brightness coefficient model is determined based on the second visual recognition data.

[0051] In a second aspect, a marking line setting method is provided, which may include:

[0052] Determining the first daytime visibility of the marking by using the daytime visibility evaluation method of the marking according to the embodiment of the present application;

[0053] If the first daytime visibility of the marking does not meet the predetermined requirement, the marking is re-applied.

[0054] Optionally, the marking line setting method may further include:

[0055] Further determining the second daytime visibility of the marking by using the daytime visibility evaluation method of the marking according to the embodiment of the present application;

[0056] If the first daytime visibility of the line marking meets the predetermined requirement but the second daytime visibility does not meet the predetermined requirement, the line marking is redrawn.

[0057] Optionally, re-marking the marking line includes:

[0058] widening the marking line according to the marking line being the first color;

[0059] According to the marking line being the second color, the diffuse reflection brightness coefficient of the marking line is increased.

[0060] In a third aspect, a road is provided, comprising a plurality of line markings, at least one of the plurality of line markings being set by the line marking setting method according to an embodiment of the present application.

[0061] The method for evaluating the daytime visibility of road markings provided in the embodiments of the present application uses the driver's daytime visibility distance of road markings as an indicator for evaluating the daytime visibility of road markings to ensure that road markings meet the driver's daytime visibility requirements under natural light conditions. A brightness contrast model based on different road marking characteristics is used to derive contrast thresholds for different types of road markings that meet the driver's daytime visibility requirements, thereby achieving a safe and reasonable daytime visibility evaluation technology for road traffic markings.

[0062] Furthermore, the method for evaluating the daytime visibility of road markings provided in the embodiments of the present application also comprehensively considers the brightness contrast model and diffuse reflection brightness coefficient model of different marking characteristics to comprehensively evaluate the daytime visibility of road markings, further improving the possibility of obtaining safe and reasonable daytime road traffic markings.

[0063] Optional features and other effects of the embodiments of the present invention are partially described below and partially understood by reading this document. BRIEF DESCRIPTION OF THE DRAWINGS

[0064] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. The elements shown are not limited to the scale shown in the drawings, and the same or similar reference numerals in the drawings represent the same or similar elements.

[0065] Figure 1 A first exemplary flow chart of a method for evaluating the visibility of a road marking during the day according to an embodiment of the present application is shown;

[0066] Figure 2 A second exemplary flow chart of a method for evaluating the visibility of a road marking during the day according to an embodiment of the present application is shown;

[0067] Figure 3 A third exemplary flow chart of a method for evaluating the visibility of a road marking during the day according to an embodiment of the present application is shown;

[0068] Figure 4 A fourth exemplary flow chart of a method for evaluating the visibility of a road marking during the day according to an embodiment of the present application is shown;

[0069] Figure 5 A fifth exemplary flow chart of a method for evaluating the visibility of a road marking during the day according to an embodiment of the present application is shown;

[0070] Figure 6 A sixth exemplary flow chart of a method for evaluating road marking visibility during the day according to an embodiment of the present application is shown;

[0071] Figure 7 A seventh exemplary flow chart of a method for evaluating road marking visibility during the day according to an embodiment of the present application is shown;

[0072] Figure 8An exemplary flow chart of a marking line setting method according to an embodiment of the present application is shown;

[0073] Figure 9 A diagram showing the variation pattern of daytime sky illumination and color temperature according to an embodiment of the present application is shown;

[0074] Figure 10 A schematic diagram of a marking test point according to an embodiment of the present application is shown;

[0075] Figure 11 A fitting curve diagram of the diffuse reflection brightness coefficient and the visual recognition distance according to an embodiment of the present application is shown. DETAILED DESCRIPTION

[0076] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention will be further described in detail below in conjunction with specific embodiments and accompanying drawings. Here, the exemplary embodiments of the present invention and their descriptions are used to explain the present invention, but are not intended to limit the present invention.

[0077] As used herein, the term "including" and its variations denote open inclusion, i.e., "including but not limited to". Unless otherwise stated, the term "or" denotes "and / or". The term "based on" denotes "based at least in part on". The terms "an example embodiment" and "an embodiment" denote "at least one example embodiment". The term "another embodiment" denotes "at least one other embodiment". To facilitate understanding of this specification, the sequential terms "first", "second", etc. are used herein to distinguish different elements / items / objects and do not denote the order or importance of different elements / items / objects. In particular, method steps expressed with the terms "first", "second", etc. are not intended to indicate the order in which the methods are executed; when an embodiment contains elements / items / objects expressed in a later order, the elements / items / objects expressed in the earlier order with the terms "first", "second", etc. are not necessarily essential technical features of the embodiment.

[0078] As mentioned above, there is currently a lack of an evaluation method for the daytime visibility of road traffic markings that can effectively meet the driver's safety visual needs.

[0079] Accordingly, the embodiments of the present application hope to provide a method for evaluating the daytime visibility of highway traffic markings based on the driver's safety visual requirements, so that the visibility of the markings can be evaluated on the basis of meeting the driver's visual requirements for highway traffic markings for safe driving during the day, and the markings can be selectively further processed according to the evaluation results.

[0080] Furthermore, the embodiments of the present application also hope to provide a marking setting method and a road, wherein the markings set by the marking setting method or the markings on the road can fully meet the driver's visual requirements for highway traffic markings for safe driving during the day.

[0081] The specific embodiments of the present application will be described in detail below with reference to the accompanying drawings. Figure 1 As shown, a method for evaluating the visibility of a road marking during the day is shown, which may include:

[0082] S110: Determining a safe sight distance at a prescribed speed on a marked road;

[0083] In the embodiments of the present application, the prescribed speed is interpreted broadly. In one embodiment, the prescribed speed is the speed limit of the road or, when there are multiple speed limits, one of the speed limits, such as the speed limit of most of the road. In one embodiment, the prescribed speed is the speed set by a person skilled in the art according to the teachings of the present invention when implementing the embodiments of the present invention, such as a speed set based on the speed limit and taking into account a safety factor; or, an average of multiple speed limits. In the embodiments of the present invention, the "prescribed speed of the road" can be, for example, the aforementioned speed limit, one of the speed limits, a set speed with a safety factor, or an average speed.

[0084] In the embodiment of the present application, the viewing distance may also be referred to as the visual distance or the visible distance.

[0085] In one embodiment of the present application, determining the safe sight distance at the prescribed vehicle speed includes: determining the safe sight distance based on the prescribed vehicle speed and a given visual recognition reaction time (also referred to as a safety preview time).

[0086] In one embodiment, the safe sight distance may conform to the following formula:

[0087] D s =V d *T s

[0088] Among them D s is the safe sight distance, V d is the specified vehicle speed, T s Preview time for safety.

[0089] S130: Determining a brightness contrast threshold of the marking based on the safe viewing distance and marking characteristics according to a brightness contrast model in which viewing distance varies with brightness contrast;

[0090] In one embodiment, the marking characteristics may include marking color and / or width. Preferably, the marking characteristics may include marking color and width. For example, marking colors may include white and yellow; marking widths may include 15 cm and 20 cm, but other colors and / or widths are contemplated.

[0091] In a further embodiment, the brightness contrast model includes a plurality of different models based on different marking features. For example, there may be a corresponding model for each different marking feature, such as each different color and each different width.

[0092] In a further embodiment, the brightness contrast model may be expressed as follows:

[0093] f i (x) = A i ln(x)+B i

[0094] Where f(x) represents the viewing distance, i refers to different models corresponding to different road marking characteristics, x represents the brightness contrast of the road marking relative to the surrounding road surface, and A and B are positive constants.

[0095] In a further embodiment, the multiple models are shown as follows:

[0096] ① For the marking line with the first color and the first width:

[0097] f1(x)=22.967ln(x)+69.488

[0098] ②For the marking line with the first color and the second width:

[0099] f2(x)=20.810ln(x)+55.729

[0100] ③For the marking line with the second color and the first width:

[0101] f3(x)=20.290ln(x)+74.571

[0102] ④ For marking lines with a second color and a second width:

[0103] f4(x)=22.260ln(x)+59.528.

[0104] In some embodiments, the first color may be white, and the second color may be yellow; the first width may be 15 cm, and the second width may be 20 cm.

[0105] S140: Obtaining the brightness contrast of the marking relative to the surrounding road surface;

[0106] In some embodiments, in step S140 , for example, a brightness contrast tool may be used to measure and determine the brightness contrast of the test reticle.

[0107] In some embodiments, the brightness contrast can be determined by measuring the brightness at multiple points of the marking and the surrounding road surface and calculating the brightness. In a preferred embodiment, the brightness can be collected in a predetermined pattern.

[0108] In some embodiments, the brightness contrast in step S140 is a vertical brightness contrast.

[0109] In some embodiments, the brightness contrast in step S140 is a vertical brightness contrast at a specified height. In some embodiments, the specified height can be 1 meter to 2 meters, preferably 1.2 meters.

[0110] In some embodiments, the luminance contrast, such as the vertical luminance contrast, is expressed as follows:

[0111]

[0112] Where: C---vertical brightness contrast between the marking and the surrounding road surface;

[0113] L p ---Vertical brightness of marking line, cd / m 2 ;

[0114] L b ---Background road surface vertical luminance, cd / m 2 .

[0115] S150: Determine the first daytime visibility of the marking line based on the acquired brightness contrast and the determined brightness contrast threshold.

[0116] In some embodiments, it may be determined that the (first) daytime visibility of the reticle does not meet the requirement based on the acquired luminance contrast being less than a determined luminance contrast threshold.

[0117] In such Figure 2 In the embodiment shown, the method for evaluating the visibility of road markings during the day may further include step S120. Figure 2 As shown, the method may include:

[0118] S110: Determining a safe sight distance at a prescribed speed on a marked road;

[0119] S120: Construct the brightness contrast model.

[0120] S130: Determining a brightness contrast threshold of the marking based on the safe viewing distance and marking characteristics according to a brightness contrast model in which viewing distance varies with brightness contrast;

[0121] S140: Obtaining the brightness contrast of the marking relative to the surrounding road surface;

[0122] S150: Determine the first daytime visibility of the marking line based on the acquired brightness contrast and the determined brightness contrast threshold.

[0123] like Figure 3 In the illustrated embodiment, step S120 may specifically include:

[0124] S121: Acquiring first visual recognition data of a plurality of drivers on road markings in at least one daytime brightness environment, wherein the first visual recognition data includes a plurality of different viewing distances corresponding to a plurality of different brightness contrasts under different road marking features;

[0125] S122: Generate the brightness contrast model by fitting the first visual recognition data.

[0126] In such Figure 4 In the illustrated embodiment, step S121 may specifically include:

[0127] S1211: For each of the multiple marking colors and widths, provide multiple test markings with multiple different brightness contrasts;

[0128] In some embodiments, each test marking may be rolled over by a heavy vehicle for different times to obtain different vertical brightness contrasts, such as 8, for each type of marking (with the same marking characteristics).

[0129] S1212: Measuring lighting characteristics of one of a plurality of daytime brightness environments, where the lighting characteristics include color temperature and / or illuminance;

[0130] In some embodiments, three daytime brightness environments with relatively large differences and relatively stable time periods can be selected, such as morning (6:00-7:00), noon (11:00-13:00), and evening (17:00-18:00).

[0131] S1213: placing one of the plurality of test markings on the road as a marking to be tested or covering the remaining test markings except the marking to be tested;

[0132] In one embodiment, multiple test markings may be drawn on a road surface (normal road or test road), as described in other embodiments herein. In step S1213 , the remaining test markings other than the markings to be tested may be covered.

[0133] In another embodiment, a plurality of test marks can be provided as separate components. Here, corresponding test marks (components) can be placed at specified positions in step S1213.

[0134] S1214: Obtaining brightness values ​​of the marking to be measured and the surrounding road surface for determining brightness contrast;

[0135] In some embodiments, the brightness value and brightness contrast of the test reticle may be obtained in a manner similar to the method of obtaining the brightness value and brightness contrast described in step S140 or in other known methods of obtaining the brightness value and / or brightness contrast.

[0136] S1215: One of the multiple drivers drives the vehicle slowly toward the test marking from a distance until the test marking appears as a horizontal line in the driver's field of view;

[0137] In one embodiment, slow speed refers to a vehicle speed of 0-10 km / h.

[0138] In a preferred embodiment, the method of causing one of the plurality of drivers to drive the vehicle slowly toward the test marking from a distance until the test marking appears as a horizontal line in the driver's field of view comprises:

[0139] The driver is required to drive the vehicle slowly towards the marking line to be measured and stop the vehicle when a horizontal line appears in the field of vision.

[0140] Although not shown, the driving direction and the line marking placement direction are set as in normal driving, so that the vehicle drives toward the line marking from a distance along the line marking placement direction.

[0141] S1216: Obtaining the distance between the vehicle and the line to be measured when a horizontal line appears in the driver's field of view as the viewing distance corresponding to the brightness contrast of the line to be measured;

[0142] S1217: Repeat steps S1215 to S1216 for each driver until completion;

[0143] S1218: Repeat steps S1213 and S1217 for each test mark until the end;

[0144] S1219: For each daytime brightness environment, repeat steps S1212 to S1218 until the end.

[0145] exist Figure 4 In the illustrated embodiment, the preceding steps may be repeated for each test line, but it is conceivable that, as an equivalent, the preceding steps may be repeated for each driver. In other words, the aforementioned steps S1217 and S1218 may have different sequences.

[0146] As an optional embodiment, step S121 may further include: adjusting the eye height of one of the multiple drivers in the vehicle.

[0147] In a further embodiment, the method for evaluating the visibility of a marking during the daytime further comprehensively considers a brightness contrast model and a diffuse reflection brightness coefficient model of different marking features to comprehensively evaluate the visibility of the marking during the daytime.

[0148] In such Figure 5 In the embodiment shown, the method for evaluating the visibility of road markings during the day may further include step S170

[0149] -190. Figure 5 As shown, the method may include:

[0150] S110: Determining a safe sight distance at a prescribed speed on a marked road;

[0151] S130: Determining a brightness contrast threshold of the marking based on the safe viewing distance and marking characteristics according to a brightness contrast model in which viewing distance varies with brightness contrast, wherein the marking characteristics include marking color and / or width;

[0152] S140: Obtaining the brightness contrast of the marking relative to the surrounding road surface;

[0153] S150: Determine the first daytime visibility of the marking line based on the acquired brightness contrast and the determined brightness contrast threshold.

[0154] S170: Determine a diffuse reflection brightness coefficient threshold of the marking based on the safe viewing distance and the marking characteristics according to a diffuse reflection brightness coefficient model in which the viewing distance varies with the diffuse reflection brightness coefficient;

[0155] S180: Obtaining the diffuse reflection brightness coefficient of the marking line;

[0156] In some embodiments, in step S180 , for example, a diffuse reflection brightness coefficient tool may be used to measure and determine the diffuse reflection brightness coefficient of the test reticle.

[0157] S190: Further determining the second daytime visibility of the marking line based on the acquired diffuse reflection brightness coefficient and the determined diffuse reflection brightness coefficient threshold.

[0158] In such Figure 6 In the illustrated embodiment, the method for evaluating the visibility of a marking during the day may further include step S160: constructing the diffuse reflection brightness coefficient model.

[0159] In such Figure 7In the illustrated embodiment, step S160 may specifically include:

[0160] S161: Acquire second visual recognition data of a plurality of drivers visually recognizing a road marking in at least one daytime brightness environment, the second visual recognition data including a plurality of different viewing distances corresponding to a plurality of different diffuse reflection brightness coefficients under different road marking characteristics;

[0161] S162: Determine the diffuse reflection brightness coefficient model based on the second visual recognition data.

[0162] In one embodiment, step S161, i.e., obtaining the second visual recognition data, can be combined with step S121, i.e., obtaining the first visual recognition distance. Accordingly, as an optional embodiment, step S121 may further include step S1212': measuring the diffuse reflection brightness coefficient (not shown) of the multiple test markings and, optionally, the surrounding road surface. In some embodiments, the diffuse reflection brightness coefficient in step S1212' can be obtained using a method similar to that described in step S180, or other known methods for obtaining the diffuse reflection brightness coefficient.

[0163] In another embodiment, the step of acquiring the second visual recognition data may be independent of the step of acquiring the first visual recognition distance.

[0164] In one embodiment, the diffuse reflection brightness coefficient model can be obtained by fitting in a manner similar to step S122. In another embodiment, the diffuse reflection brightness coefficient model can be obtained by forming a lookup table or by fitting first and then forming a lookup table.

[0165] In the embodiments of this application, Figure 8 As shown, a marking line setting method can also be provided, which may include:

[0166] S810: Determine the first daytime visibility of the marking using a marking daytime visibility evaluation method;

[0167] S820: If the first daytime visibility of the line marking does not meet the predetermined requirement, redraw the line marking.

[0168] In the embodiment of the present application, the method for evaluating the visibility of a road marking during the day is the method for evaluating the visibility of a road marking during the day according to the embodiment of the present application.

[0169] Optionally, the method may further include:

[0170] S830: Further determining the second daytime visibility of the marking using a marking daytime visibility evaluation method;

[0171] S840: If the first daytime visibility of the line marking meets the predetermined requirement but the second daytime visibility does not meet the predetermined requirement, redraw the line marking.

[0172] Optionally, re-marking the marking line may include:

[0173] widening the marking line according to the marking line being the first color;

[0174] According to the marking line being the second color, the diffuse reflection brightness coefficient of the marking line is increased.

[0175] Optionally, since the marking line is the second color, the marking line is also widened at the same time.

[0176] In an embodiment of the present application, a road may be provided, comprising a plurality of line markings, at least one of the plurality of line markings, and preferably all of the line markings are set by the line marking setting method according to the embodiment of the present application.

[0177] In an embodiment of the present invention, a device for evaluating the daytime visibility of a road marking is further provided, which may include: a visual distance determination unit, configured to determine a safe visual distance at a prescribed vehicle speed on a road with markings; a threshold determination unit, configured to determine a brightness contrast threshold of the road marking based on a brightness contrast model in which the visual distance changes with brightness contrast, based on the safe visual distance and road marking characteristics; a contrast acquisition unit, configured to acquire the brightness contrast of the road marking relative to the surrounding road surface; and a first visibility determination unit, configured to determine the first daytime visibility of the road marking based on the acquired brightness contrast and the determined brightness contrast threshold.

[0178] In an embodiment of the present invention, a marking setting device is also provided, which may include: a determination unit, configured to determine the daytime visibility of the marking by using the daytime visibility evaluation method and / or device of the embodiment of the present application; and a marking unit, configured to re-mark the marking if the first daytime visibility of the marking does not meet predetermined requirements.

[0179] Under the teachings of the present invention, the features of the method embodiment can be combined with the device embodiment in a non-contradictory manner to obtain a new embodiment, and the features of the device embodiment can also be combined with the method embodiment in a non-contradictory manner to obtain a new embodiment, which falls within the scope of the present invention.

[0180] By way of explanation and not limitation, the inventors realized that outdoor vehicle tests can be conducted to test the maximum visible distance of markings with different brightness contrasts between the markings and the road background under diffuse sunlight lighting conditions at different times of the day, and to analyze the relationship model between the brightness contrast between the markings and the road background and the visible distance; and based on the research on the driver's demand for the visible distance of the markings, by constructing a relationship model between the visible distance and the brightness contrast under the most unfavorable conditions, the required threshold value of the brightness contrast between the markings and the road background under different road conditions during the day is proposed.

[0181] Therefore, the daytime visibility evaluation method for road markings provided by the embodiments of this application can determine the brightness contrast threshold based on a specified vehicle speed by using different brightness contrast models constructed based on different types of road markings (marking features). This can be used to determine the technical parameters for road marking visibility design that meet the driver's visual needs. Therefore, the embodiments of this application, on the one hand, address the shortcomings of studying the technical parameters for daytime road marking visibility from the perspective of driver safety visual needs; on the other hand, they can help create a good, reliable, and safe driving visual environment, addressing the driving safety risks caused by insufficient visibility of road markings during the day.

[0182] To further describe various embodiments of the present invention, and to demonstrate how to evaluate the daytime visibility of road markings based on a luminance contrast model and further evaluate the daytime visibility of road markings using a diffuse reflection luminance coefficient model, thereby meeting the driver's daytime visual safety needs, the following describes the construction of a luminance contrast model and related experiments and analyses using specific embodiments. The various features of the specific embodiments described below can be combined, either individually or in combination, with the various embodiments described above in a non-contradictory manner to obtain new embodiments. In particular, the formulas of the specific embodiments described below can be combined with the various embodiments described above to obtain new embodiments, which falls within the scope of the invention.

[0183] Example

[0184] In this embodiment, in order to ensure that road traffic markings can meet the safety visibility requirements of daytime drivers during the operational phase, the following tests and processing are conducted on the daytime drivers' visibility requirements for road traffic markings and the daytime drivers' visibility of different types of markings to obtain a corresponding model for determining the daytime visibility of the markings.

[0185] Since the edge line on the road is a rectangular line, and as the driver drives closer to the line marking, the line marking will be diffusely reflected into the driver's field of view, and the state of the surface will be presented in the driver's field of view.

[0186] Furthermore, under daytime conditions, the markings visible in the driver's field of view are rectangular surfaces composed of horizontal lines that form a brightness or chromaticity contrast with the road surface. Therefore, the distance between the driver's position (position A) and the part of the marking closest to the driver when the visual state is a rectangular surface composed of horizontal lines (position B) can be defined as the visible distance of the marking (not marked), which represents the intuitive feeling of the actual road markings obtained from the driver's eye recognition angle. The distance of the visible distance indicates the quality of the visibility of the markings. The longer the visible distance, the better the visibility of the markings. Therefore, the embodiment of the present application uses the visible distance of the markings as an indicator for evaluating the daytime visibility of the markings, and studies the influence of the brightness contrast coefficient, width and color of the markings on the daytime visibility of the markings.

[0187] As further described below, by analyzing the changes in the state of road markings in the driver's field of view during driving, a classification of road marking visibility status was established, as shown in Table 1. Considering the daytime visibility function of road markings, the standard for meeting the driver's visibility requirements is meeting the Level 2 requirement.

[0188] Table 1 Evaluation table of road marking visual status

[0189]

[0190] Test subjects

[0191] The high speed and strong maneuverability of passenger cars make the field of vision of passenger car drivers usually narrower than that of large truck drivers. The faster speed and lower eye height result in shorter visibility, which is not conducive to the driver's safe vision. According to the principle of the most unfavorable vision, passenger cars were selected as test vehicles.

[0192] According to the 2020 driver statistics of the Ministry of Public Security, there are 308 million male drivers in my country's motor vehicle drivers, accounting for 67.57%, and 148 million female drivers, accounting for 32.43%. The male-to-female ratio is about 7:3. Taking into account the driver's vision and gender ratio factors, this experiment used a convenient sampling method to select 36 healthy and well-rested passenger car drivers, including 25 male drivers and 11 female drivers; the naked or corrected vision of both eyes reached 4.9 or above, and there were no eye diseases such as color blindness and color weakness.

[0193] Test parameter selection

[0194] Considering the practicality of the project, the sunlight illuminance and color temperature of the test site from 6:00 to 18:00 under clear weather were tested before the formal test. Figure 9As shown, over time, illuminance gradually increases and color temperature gradually decreases. When it increases or decreases to a certain value, it remains stable, then illuminance decreases and color temperature increases. The illuminance ranges from 2000 to 25000 lx; ​​the color temperature ranges from 5400 to 8500K. Based on this variation pattern, three time periods with relatively large differences and stable lighting conditions were selected: morning (6:00-7:00), noon (11:00-13:00), and evening (17:00-18:00). Specific illuminance and color temperature values ​​are subject to those measured during formal testing.

[0195] According to the "Road Traffic Signs and Markings" (GB 5768.3-2009), road markings are generally white and yellow. The "Quality Requirements and Test Methods for Road Traffic Markings" (GB / T 16311-2009) also specifies the chromaticity coordinate range and luminance factor β for white and yellow road markings. Furthermore, 15 cm and 20 cm are the most common widths of road markings. Based on the design and usage of existing road markings, the marking samples used in this test were white and yellow, with widths of 15 cm and 20 cm and a length of 1 meter. Four types of markings were applied on an asphalt test road, with eight lines of each type. Strict control of the construction process ensured that the thickness of all 32 test markings remained consistent, ranging from 0.4 mm to 2.5 mm. By running heavy vehicles over each marking a different number of times, eight different vertical luminance contrast ratios were achieved for each marking type. The measured range of the vertical brightness contrast between the white marking and the road surface is between 0 and 8; the measured range of the vertical brightness contrast between the yellow marking and the road surface is between 0 and 6.

[0196] In this embodiment, brightness contrast is a parameter used to determine the visibility of the marking. Because brightness is affected by various factors such as angle and distance, this specific embodiment uses the vertical brightness contrast at a height of 1.2 meters. The vertical brightness contrast is calculated as shown in the following formula.

[0197]

[0198] Where: C---vertical brightness contrast between the marking and the road surface;

[0199] L p ---Vertical brightness of the marking line, cd / m 2 ;

[0200] L b ---Background road surface vertical luminance, cd / m 2 .

[0201] Test equipment

[0202] The test uses a CS-150 single-lens reflex spot luminance meter, which can be used to measure light source and surface brightness, to measure the vertical luminance between the marking and the background road surface. The luminance measurement range is 0.001 to 299,900 cd / m 2 The brightness measurement accuracy is ±2% and the repeatability is 0.2%. RGB images of the road markings and background road surface, taken under the same conditions, were used to assist in calculating brightness contrast. The image has 8.2 million effective pixels and a maximum resolution of 3504×2336. A Konica Minolta CL-500A spectroradiometer was used to measure the color temperature and illuminance of the natural light environment. A wheel rangefinder was used to measure the visual distance between the driver and the target road marking.

[0203] Test site introduction

[0204] Taking into account factors such as driving safety, eliminating distractions to the driver's line of sight, and ease of marking and replacement, the test was conducted under clear daylight conditions on a 200-meter-long, 3.75-meter-wide, flat, straight test road section at the Zhejiang Huzhou Brothers Road Marking Coatings Co., Ltd. The facility provides road markings with varying brightness and contrast, ensuring a dry surface that accurately reflects normal road conditions.

[0205] Test steps

[0206] Based on safety and the accuracy and validity of the test data, the test subjects were trained one day before the test to ensure that each subject was familiar with the test driving tasks and the test officially began after two training sessions.

[0207] Taking the 1# test marking sample as an example, the specific test process is as follows:

[0208] 1) Cover the 2# to 32# test markings with black non-reflective cloth, measure the diffuse reflection brightness coefficient of the 1# test marking and the surrounding road surface, and record it in the data table.

[0209] 2) Between 6:00 and 7:00 in the morning, place the spectroradiometer on the road with the probe facing the sky and connect it to a computer. Measure the color temperature and illuminance of natural light every 5 minutes. Save the file and record it in a data table at the end of the test.

[0210] 3) Modulate the camera to output RAW file format, take photos vertically downward, and record the picture number in the data table; measure the spot brightness meter vertically downward as shown in the following example: Figure 10 The luminance values ​​of the three points in the marking area and the eight points on the adjacent road surface are recorded in the data table; the height of the camera and the point luminance meter are both 1.2m.

[0211] 4) Each participant slowly drives their vehicle toward the marked area from a distance and visually identifies the area, maintaining the vehicle in the center of the lane. When a horizontal line appears in their field of vision, they stop the vehicle. Using a roller distance meter, measure the distance between the driver's seat and the center of the sample marking and record it in the data sheet.

[0212] 5) Repeat the above steps for the remaining 2# to 32# test markings.

[0213] 6) Repeat the morning measurement and visual identification work between 11:00-13:00 in the afternoon and 17:00-18:00 in the evening.

[0214] The test collected 96 sets of test data for 32 road marking templates during the morning, midday, and evening hours. Each set included the visual distance, road marking brightness, adjacent road surface brightness, ambient light color temperature, and illuminance of 36 passenger car drivers.

[0215] Considering the road function of existing road markings, the visual field state corresponding to Level 2 in Table 1 served as the visual recognition standard for the test subjects. After the test, the test subjects reported that the visual field state of markings 1-5, 9-13, 17-21, and 25-29 changed from Level 1 to Level 3. This means that the tested markings went from invisible to blocky, making it difficult to determine the test subject's position at Level 2. When visually identifying other markings, the test subject's position at Level 2 was easily determined. The recorder can note this information in the data sheet.

[0216] Analysis and model construction of the relationship between brightness contrast and driver's visual distance

[0217] Statistical analysis was used to test for differences between male and female test subjects. The test result, P = 0.34, was less than 0.05, indicating no differences between male and female test drivers. To improve the accuracy and validity of the test data, the effective visual distance of the road marking was determined by the distance at which 85% of the test drivers could clearly see the road marking. The test data was categorized, organized, and analyzed, resulting in a total of 85 valid test sample groups for driver recognition results.

[0218] Tests have found that white markings offer better visibility than yellow markings under the same conditions, and 20cm-wide markings offer better visibility than 15cm-wide markings. The color of the markings seen by drivers is related to the color of the light reflected by the markings. White light is a composite light with a wavelength of 400-760nm, while yellow light is a monochromatic light with a wavelength of 570-600nm. The longer the wavelength of light, the lower the frequency, and the lower the frequency, the less energy a single photon has. Due to its long wavelength, light has a strong diffraction capacity, meaning that longer wavelengths propagate farther and are less likely to dissipate. Therefore, in engineering applications, increasing the diffuse reflectance brightness coefficient of yellow markings to improve visibility is difficult. Instead, increasing the width of yellow markings to meet visibility requirements is recommended. For white markings, the cost of increasing the diffuse reflectance coefficient versus the economic cost of increasing the width can be considered.

[0219] The analysis used the brightness contrast of the markings and the driver's 85% visual distance of the target marking as characteristic values. The data analysis revealed that within a certain range of brightness contrast between the markings and the road surface, the driver's visual distance of the markings was positively correlated with the brightness contrast. Specifically, as the brightness contrast increased, the visual distance gradually increased. Under the same lighting conditions and width, white markings were more visually recognizable than yellow markings. Under the same lighting conditions and color, a 20cm-wide marking was more recognizable than a 15cm-wide marking. However, when the vertical brightness contrast between a white marking and the road surface exceeded 4, or when the vertical brightness contrast between a yellow marking and the road surface exceeded 3, the visual distance of the markings no longer varied with increasing brightness contrast. At this point, the visual distance of the markings was primarily influenced by their length. This is because the human eye has a limiting resolution angle, a physical quantity that describes its ability to distinguish two closely spaced objects. As the driver's distance from the road marking increases, the resolution angle formed by the near endpoint of the marking, the human eye, and the far endpoint gradually decreases, and the length of the marking in the field of view gradually decreases. When it reaches the threshold of the human eye, it appears as a horizontal line. As background brightness and contrast decrease, the human eye's limiting resolution angle significantly increases. Therefore, when the vertical brightness contrast between the marking and the road surface is large, the visible distance of the marking is also affected by the human eye's limiting resolution angle.

[0220] Tests have found that changes in the natural light environment affect the daytime visibility of road markings, and this effect is consistent across markings of varying widths and colors. Measurements of road marking visibility during three time periods during a clear, cloudless day show that the markings are visible the furthest during the periods of highest illumination and lowest color temperature, while the markings are visible the closest during the periods of lowest illumination and highest color temperature. The changing trends in the color temperature and illumination of the natural light environment throughout the day indicate that the color temperature is highest and the illumination is lowest during the twilight period between day and night, making road marking visibility the most unfavorable. Based on the most unfavorable principle, the brightness contrast threshold for road markings was selected based on the test results from the evening hours.

[0221] According to the above quantitative analysis, the driver's visual distance for different color and width markings in different time periods is positively correlated with the brightness contrast. The brightness contrast and visual distance values ​​obtained from the evening test are substituted into the data and the sample points are plotted. It is found that the brightness contrast and visual distance conform to the logarithmic function model distribution. Therefore, nonlinear regression analysis can be used to fit the logarithm function model to describe the function data, such as Figure 11 The final fitting function model is shown as follows:

[0222] f i (x) = A i ln(x)+B i

[0223] Where f(x) represents the sight distance, i refers to different models corresponding to different road marking features, x represents the brightness contrast of the road marking relative to the surrounding road surface, A and B are positive constants, and their values ​​vary depending on the color and width of the road marking. The specific values ​​are shown in Table 2.

[0224] Table 2 Different model parameters for different marking features

[0225]

[0226] where R 2 is the goodness of fit.

[0227] In this specific embodiment, the first visual recognition data collected in all three time periods, i.e., three daytime brightness environments, are used to construct the model, but it is conceivable that the first visual recognition data collected in at least one of the daytime brightness environments can be used to construct the model, for example, using the most unfavorable daytime brightness environment (such as dusk).

[0228] Selection of road marking brightness contrast threshold to meet driver's visual safety needs

[0229] Based on this, the safe sight distance at different speeds and the daytime visibility evaluation index thresholds of different types of road traffic markings are determined.

[0230] For example, based on the multiple diffuse reflection brightness coefficient models of brightness contrast coefficient and visual distance established in this embodiment, the markings with different characteristics (color and width) can be calculated using a safe preview distance of 3.65s for different prescribed vehicle speeds, such as brightness contrast thresholds under different speed limits.

[0231] Based on the proposed model for the vertical brightness contrast between different road markings (with different marking features) and adjacent road surfaces, the preview distance at different speeds was calculated using a preview time of 3.65 seconds. The vertical brightness contrast thresholds for different types of road markings at different speeds under the most unfavorable natural light environment were obtained, as shown in Table 3.

[0232] Table 3 Vertical brightness contrast thresholds between different types of road markings and adjacent road surfaces

[0233]

[0234] Furthermore, a diffuse reflection brightness coefficient model can be constructed (e.g., in the form of a fitted curve or a lookup table similar to that shown in Table 4 below). Thus, the diffuse reflection brightness coefficient model can be used to assist or further determine the daytime visibility of the marking. In this specific embodiment, the second visual recognition data collected in the most unfavorable daytime brightness environment (e.g., evening) is used to construct the model. However, it is contemplated that the second visual recognition data collected in at least one or all daytime brightness environments can be used to construct the model.

[0235] By way of explanation and not limitation, the inventors discovered that data analysis of the vertical brightness contrast between the road marking and the road surface and the diffuse reflection brightness coefficient Qd under the most unfavorable natural light environment revealed a significant linear relationship between the two. The threshold value of the diffuse reflection brightness coefficient Qd of the road marking that meets the driving safety perception requirements under the most unfavorable natural light environment was calculated through a regression model, as shown in Table 4. This can provide an auxiliary reference for maintaining the visibility performance of road markings during daytime operation.

[0236] Table 4 The threshold of diffuse reflection brightness coefficient of marking line under the most unfavorable natural light environment

[0237]

[0238]

[0239] The inventors discovered that a driver's ability to discern road markings depends on their prominence against the road surface. Furthermore, the diffuse reflectance properties of both the road markings and the road surface they sit on vary during operation. Therefore, the current method of measuring the diffuse reflectance brightness coefficient (Qd) of road markings, a single indicator, for evaluating daytime road marking visibility seems unsuitable.

[0240] In an embodiment of the present application, the daytime visibility of the marking is determined by using a brightness contrast model based on the marking characteristics (color and width) and further confirming the daytime visibility of the marking in combination with the diffuse reflection brightness coefficient model, thereby avoiding the problems existing in the current diffuse reflection brightness coefficient measurement method. In particular, the inventors realized that the main factor affecting the driver's safety vision needs is the brightness contrast between the marking surface and the background road surface. At the same time, the inventors also realized that the diffuse reflection brightness coefficient of the marking only characterizes the reflective ability of the marking material itself. The current measurement method measures a fixed light source, which may cause the diffuse reflection brightness coefficient of the same marking to remain unchanged. When the external light environment changes, its visibility is different. Therefore, the diffuse reflection brightness coefficient measurement method cannot effectively express the impact of changes in the natural light environment during the day, and cannot fully characterize the ability of the marking to provide a safe sight distance for the driver during the operation phase. Moreover, the current diffuse reflection brightness coefficient measurement method is still difficult to simulate the light environment characteristics such as brightness and color temperature under the natural light environment during the day.

[0241] In contrast, the embodiment of the present application provides different brightness contrast models for different road marking features, and accordingly determines the corresponding brightness contrast threshold requirements based on the specified vehicle speed. This meets the driver's safety vision needs from the perspective of the driver's daytime safety vision needs, and conforms to the daytime driver's vision rules for different types of road markings, thereby obtaining a daytime highway traffic marking visibility evaluation method that meets the driver's safety vision needs, thereby providing strong support for daytime highway traffic marking visibility evaluation, in order to achieve a safe, comfortable and reasonable daytime road traffic marking setting technology.

[0242] Unless explicitly stated, the actions or steps of the methods, procedures, and methods described in accordance with the embodiments of the present invention do not have to be performed in a specific order and can still achieve the desired results. In some implementations, multitasking and parallel processing are also possible or may be advantageous.

[0243] In this document, multiple embodiments of the present invention are described, but for the sake of brevity, the description of each embodiment is not exhaustive, and the same or similar features or parts between the embodiments may be omitted. In this document, "one embodiment", "some embodiments", "example", "specific example", or "some examples" are intended to apply to at least one embodiment or example according to the present invention, but not all embodiments. The above terms do not necessarily mean to refer to the same embodiment or example. Those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, unless they are mutually contradictory.

[0244] While the exemplary systems and methods of the present invention have been specifically shown and described with reference to the foregoing embodiments, these are merely examples of the best modes for implementing the present systems and methods. Those skilled in the art will appreciate that various changes may be made to the embodiments of the systems and methods described herein when implementing the present systems and / or methods without departing from the spirit and scope of the present invention as defined in the appended claims.

Claims

1. A method for evaluating the visibility of road markings during the day, characterized in that: include: determining a safe sight distance at a prescribed speed on a road with markings; Determining a brightness contrast threshold of the marking based on the safe viewing distance and marking characteristics according to a brightness contrast model in which viewing distance varies with brightness contrast, the marking characteristics including marking color and / or width; Obtain the brightness contrast of the markings relative to the surrounding road surface; determining a first daytime visibility of the reticle based on the acquired luminance contrast and the determined luminance contrast threshold; Determining a diffuse reflection brightness coefficient threshold of the marking based on the safe viewing distance and the marking characteristics according to a diffuse reflection brightness coefficient model in which the viewing distance varies with the diffuse reflection brightness coefficient; Obtaining the diffuse reflection brightness coefficient of the marking line; further determining the second daytime visibility of the marking based on the acquired diffuse reflection brightness coefficient and the determined diffuse reflection brightness coefficient threshold; The brightness contrast model includes multiple models based on different marking line features, and is shown in the following formula: f i (x)=A i ln(x)+B i Where f(x) represents the viewing distance, i refers to different models corresponding to different marking characteristics, x represents the brightness contrast of the marking relative to the surrounding road surface, and A and B are positive constants; The multiple models are shown in the following formula: ① For the marking line with the first color and the first width: f1(x)=22.967ln(x)+69.488 ②For the marking line with the first color and the second width: f2(x)=20.810ln(x)+55.729 ③For the marking line with the second color and the first width: f3(x)=20.290ln(x)+74.571 ④ For marking lines with a second color and a second width: f4(x)=22.260ln(x)+59.

528.

2. The method for evaluating road marking visibility during the day according to claim 1, wherein: Also includes: The brightness contrast model is constructed.

3. The method for evaluating road marking visibility during the day according to claim 2, wherein: Desirably, constructing the brightness contrast model comprises: Acquiring first visual recognition data of a plurality of drivers recognizing road markings in at least one daytime brightness environment, the first visual recognition data including a plurality of different viewing distances corresponding to a plurality of different brightness contrasts under different road marking features; The brightness contrast model is generated by fitting the first visual recognition data.

4. The method for evaluating road marking visibility during the day according to claim 3, wherein: Acquiring first visual recognition data of a plurality of drivers visually recognizing a road marking in at least one daytime brightness environment includes: S1211: For each of the multiple marking colors and widths, provide multiple test markings with multiple different brightness contrasts; S1212: Measuring lighting characteristics of one of a plurality of daytime brightness environments, where the lighting characteristics include color temperature and / or illuminance; S1213: placing one of the plurality of test markings on the road as a marking to be tested or covering the remaining test markings except the marking to be tested; S1214: Obtaining brightness values ​​of the marking to be measured and the surrounding road surface for determining brightness contrast; S1215: One of the multiple drivers drives the vehicle slowly toward the line to be measured from a distance until the line to be measured appears as a horizontal line in the driver's field of view; S1216: Obtaining the distance between the vehicle and the line to be measured when a horizontal line appears in the driver's field of view as the viewing distance corresponding to the brightness contrast of the line to be measured; S1217: Repeat steps S1215 to S1216 for each driver until completion; S1218: Repeat steps S1213 and S1217 for each test mark until the end; S1219: For each daytime brightness environment, repeat steps S1212 to S1218 until the end.

5. The method for evaluating road marking visibility during the day according to any one of claims 1 to 4, characterized in that: Also includes: Construct the diffuse reflection brightness coefficient model.

6. The method for evaluating road marking visibility during the day according to claim 5, characterized in that: The constructing of the diffuse reflection brightness coefficient model comprises: Acquiring second visual recognition data of a plurality of drivers recognizing a road marking in at least one daytime brightness environment, the second visual recognition data including a plurality of different viewing distances corresponding to a plurality of different diffuse reflection brightness coefficients under different road marking characteristics; The diffuse reflection brightness coefficient model is determined based on the second visual recognition data.

7. A marking line setting method, characterized in that: include: Determining the first daytime visibility of the marking by the method for evaluating the daytime visibility of the marking according to any one of claims 1 to 6; If the first daytime visibility of the marking does not meet the predetermined requirements, re-marking the marking; further determining the second daytime visibility of the marking by the method for evaluating the daytime visibility of the marking according to any one of claims 1 to 6; If the first daytime visibility of the line marking meets the predetermined requirement but the second daytime visibility does not meet the predetermined requirement, the line marking is redrawn.

8. A road comprising a plurality of markings, characterized in that: At least one of the plurality of marking lines is set by the marking line setting method according to claim 7.

Images