JP2000123300A - Method and device for detecting white line accompanied with correction based on disappearing point - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make compatible robustness and high accuracy by estimating a disappearing point while using only lines, in which a specified number of lines alternately cross near, out of the combination of detected white lines or road end lines and other lines found from substitutive feature points. SOLUTION: A picked-up image is provided by an image pick means 801 and lines such as white lines or road end lines more than four are extracted by a means 802 for estimating the white line/road end line from the feature points of white lines/road ends with respect to this image. Next, three lines are selected out of detected lines and three intersections are found by applying a means for finding the mutual intersections of three estimated lines. Afterwards, the distance of three intersections is evaluated by a means 804 for evaluating it as an index, three intersections to most shorten the sum of mutual distance is found and the other intersections are excluded. In respect to three intersections to most shorten the sum of mutual distances, the disappearing point is estimated by a means 805 for estimating the disappearing point from recent three intersections.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for detecting a white line from road image information captured by an on-vehicle camera, and more particularly to a method and an apparatus for calculating a vanishing point where straight lines such as road edge lines intersect. The present invention relates to a white line detection method with correction.

[0002]

2. Description of the Related Art When detecting a road area or the like from image information captured by an on-vehicle camera, processing is performed to find a vanishing point where a road edge line such as a white line crosses. As the calculation of the vanishing point, for example, in Japanese Patent Application Laid-Open No. 7-78255, when the vanishing point is determined as an intersection of a straight line portion in the screen, when the points on the screen are sequentially processed according to a predetermined method, the color tone and the like are determined. By extracting the point at which the stable state where the change is small and the unstable state where the change of the color tone is large is extracted as a line candidate point, not only the white line, but also the straight line portion corresponding to the median strip and the roadside zone, A method has been proposed in which the calculation accuracy of a road vanishing point is improved.

By the way, the road edge estimated from the image information should originally intersect at one point on the vanishing point due to the parallelism of the line on the road. As shown in FIG. 1, they do not intersect at one point.

[0004]

That is, the conventional vanishing point calculation method has the following problems.

The first problem is that the vanishing point obtained by detecting a road white line has low accuracy. Further, since the subsequent image processing and vehicle control are performed on the basis of this vanishing point, the low calculation accuracy of the vanishing point affects the control of the vehicle.

[0006] The reason is that the vanishing point is extrapolated (extrapolated),
This is because the calculation is performed by obtaining the intersection, and thus the calculation is greatly affected by the calculated variation in the inclination of the white line, and the position of the intersection greatly changes.

[0007] The second problem is that it is difficult to secure the accuracy of line estimation alone.

The reason is that systematic error factors such as certain shadows occur frequently in outdoor images.

Accordingly, the present invention has been made in view of the above problems, and an object of the present invention is to provide a vanishing point calculation method and apparatus capable of achieving both robustness and high accuracy.

[0010]

According to the present invention, which achieves the above objects, the present invention can be summarized as follows: a white line or a road edge detected; By estimating the vanishing point by using only the line where the line intersects alternately, robustness and high accuracy are achieved.

According to the present invention, a white line and a road edge line or a line from a white line, a road edge line, and an alternative feature point are estimated from a captured image, and three or more of the estimated lines are mutually reciprocated. From the intersections, three intersections of three lines that minimize the sum of the distances between the intersections (referred to as “most recent three intersections”) are taken out, and an average position of the three intersections is set as an estimated vanishing point.

In the detection of a lane (white line), a vanishing point of a detected white line or a road edge line or a line obtained from another alternative feature point is used to detect a falsely detected white line or a road edge line or another alternative line. By excluding the line obtained from the feature points, the line of the estimation result having low consistency is not used.

[0013]

Embodiments of the present invention will be described. In FIG. 1, three intersections where the sum of the mutual distances is the shortest are taken out of a total of six intersections of four white lines and road end lines, for three points corresponding to the three lines, and the average position is shown in FIG. And an estimated vanishing point as shown in FIG. The vanishing point can be calculated with high reliability and high accuracy, and by using the estimated vanishing point, robustness and improvement in accuracy of white line detection are realized.

When the road is a curve, the above effect is obtained by using a tangent line instead of a straight line estimated from the left and right white lines and the road end line.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to the drawings.

FIG. 9 is a diagram showing the configuration of one embodiment of the present invention. FIGS. 1, 2 and 3 are diagrams for explaining an embodiment of the present invention.

Referring to FIG. 9, an apparatus according to an embodiment of the present invention estimates a white line and a road edge line from characteristic points such as a white line and a road edge from image information acquired by an image imaging unit 801. 802, means 803 for obtaining three mutual intersections of the estimated line, means 804 for evaluating the distance between the three intersections as an index, and means 805 for estimating a vanishing point from the closest three intersections.

The image pickup means 801 causes the picked-up image 10
1, and the white line 10 is estimated by the means 802 for estimating the white line / road edge from the characteristic points such as the white line / road edge.
2. Extract four or more lines such as the road edge line 103.

Next, three lines are selected from the detected lines, and a means 80 for determining the three intersections of the estimated lines is provided.
3 is applied to obtain three intersections, and then evaluated by means 804 for evaluating the distance between the three intersections as an index, the three intersections 107 having the shortest sum of mutual distances are obtained, and other intersections are excluded. .

For the three intersections 107, the vanishing point 104 is estimated by means 805 for estimating the vanishing point from the three most recent intersections.

The functions of these means 802 to 805 may be realized by program control executed on a computer. In this case, the present invention can be implemented by a computer reading and executing the program from a recording medium storing the program.

Next, the overall operation of the present embodiment will be described in detail with reference to FIGS.

A captured image 101 of a road captured from a vehicle
, A total of four lines of a white line 102 and a road end line 103 are estimated.

As shown in FIG. 2, which is a partially enlarged view of 106 in FIG. 1, the intersections do not always intersect at one point. For this reason, the degree of coincidence between the three lines is evaluated based on the distance between the intersections of the three lines.

As a result, it is possible to find the three lines that intersect at the closest point and the three most recent intersections 107. As shown in FIG. 3 which is a partially enlarged view of 109 in FIG.
0 is the estimated position of the vanishing point.

As the average position, for example, when recalculating a line passing through the vanishing point, (1) a simple average or the center of gravity from a load corresponding to the reliability of the line forming the intersection,
(2) Inner center when the estimated line inclination is stored and the estimated line is translated and (3) Outer center when the line inclination correction is suppressed, and the average position in the processing according to the subsequent processing. To estimate the vanishing point.

Next, a second embodiment of the present invention will be described. FIGS. 4 to 8 are diagrams for explaining a second embodiment of the present invention.

Referring to FIG. 4, the detected white line 102,
Line 11 estimated from alternative feature points other than road edge line 103
1 is also used to calculate three intersections for a combination of three lines for more estimated lines.

In this case, as shown in FIG. 5, a determination is made in order of priority by giving a point or using the reliability of the detected line for each target type of the detected line. If an item that meets the judgment criteria is within the range, no further judgment is made. In the example shown in FIG. 5, a point is attached for each line type,
The priority of the three lines is obtained, and the detected white line 102
Is a point 1, a line which is a road edge line 103, a point 2, a line which is a line 111 from a representative feature point is a point 3, and a white line, a white line, a road edge line or a road is determined for three combinations. In the case of the combination of the end lines, the point has the highest priority of 1 + 1 + 2 = 4, and in the case of the combination of the road single line and the line from the alternative feature point, the point has the priority of 2 + 2 + 3 = 7 and the lowest priority.

It should be noted that the detection reliability of the line (for example, 0.
8, 0.5, 0.4, 0, 6, 0.3) may be used to determine the priority.

FIG. 6 is a schematic diagram for explaining the state of the judgment. As shown in FIG. 6, weights are provided according to the estimated line type, not the sum of the simple distances at the three intersections, and the weighted distance evaluation is performed. That is, L = L1 × 1 + L2 × L3 × 3 as three-point distance L1: Estimated distance between intersections on white line Load = 1 L2: Estimated distance between intersections on road edge line Load = 2 L3: From estimated alternative feature amount Distance between intersections on the line
Load = 3

At the same time, as shown in FIG. 7, a combination of lines on the same side (lines in the same inclination direction) is excluded from the judgment because the position calculation accuracy of the intersection is low.

As shown in FIG. 8, the estimation of the vanishing point from the three most recent intersections and the recalculation of the estimated line are performed by parallel movement (parallel movement) using the inner center so that the estimated line passes on the inner center at the same time. There is also a method of shifting.

This is applied to the case where the inclination information is important in lane running, and this information is stored.

Note that, as a standard, the line of gravity is re-estimated with the center of gravity of the three intersections as the estimated vanishing point, and passing through the center of gravity as a constraint.

[0036]

As described above, according to the present invention,
The following effects are obtained.

A first effect of the present invention is that a vanishing point serving as a reference for image processing can be obtained robustly and with high accuracy.

The reason is that, in the present invention, considering the reliability of the estimated line, the three lines used for estimating the vanishing point are selected based on the degree of unity of the three intersections of the selected three lines. This is because the estimation line with a large amount of error, which is dragged by the exception data, is excluded from the vanishing point estimation.

A second advantage of the present invention is that the line can be re-estimated.

The reason is that, in the present invention, since the accuracy of the vanishing point obtained is high, when re-evaluating a line while changing the slope through this vanishing point, if the vanishing point precision is low, This is because flattening of the peak of the generated line evaluation value can be suppressed.

[Brief description of the drawings]

FIG. 1 is a diagram for explaining an embodiment of the present invention.

FIG. 2 is a diagram for explaining one embodiment of the present invention;
FIG. 2 is a partially enlarged view of a region 106 in FIG. 1.

FIG. 3 is a diagram for explaining one embodiment of the present invention;
FIG. 3 is a partially enlarged view of a region 109 in FIG. 2.

FIG. 4 is a diagram for explaining a second embodiment of the present invention.

FIG. 5 is a diagram for explaining a second embodiment of the present invention.

FIG. 6 is a diagram for explaining a second embodiment of the present invention.

FIG. 7 is a diagram for explaining a second embodiment of the present invention.

FIG. 8 is a diagram for explaining a second embodiment of the present invention.

FIG. 9 is a diagram showing a configuration of one embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 101 Captured image 102 Detected white line 103 Detected road edge line 104 Estimated vanishing point 105 Road edge line excluded from estimation 106 Partial region of captured image 107 Recent three intersections (three intersections where evaluation index becomes minimum) 108 Exclusion 3 intersections 109 to be performed 109 Partial area 110 Average position of the latest 3 intersections 111 Lines detected from alternative feature amounts 112 Partial view of captured image 113 Three intersections of three lines in an example of distance calculation 801 Image capturing means 802 White line road end estimating means 803 Means for finding the intersection of the estimated three lines 804 Means for evaluating the index of the distance between the three intersections 805 Means for estimating the vanishing point from the three intersections

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[Procedure amendment]

[Submission date] September 27, 1999 (September 9, 1999
7)

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Claims

[Correction method] Change

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[Claims]

[Procedure amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0011

[Correction method] Change

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According to the present invention, a white line and a road edge line or a line from a white line, a road edge line, and an alternative feature point are estimated from a captured image, and three or more of the estimated lines are mutually reciprocated. From the intersections, three intersections of three lines that minimize the sum of the distances between the intersections (referred to as “most recent three intersections”) are taken out, and an average position of the three intersections is set as an estimated vanishing point. White line of the present invention
In the detection method, the estimated position from the three most recent intersections is
Using the inner center, and re-estimating the line, save the slope,
Minimize the correction of the estimated line position. In addition, the recent three
Using the center of gravity as the estimated position from the point, and re-estimating the line,
It is re-estimated as a line passing through the center of gravity. ────────────────────────────────────────────────── ───

[Procedure amendment]

[Submission date] December 20, 1999 (1999.12.
20)

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Claims

[Correction method] Change

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[Claims]

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Yuji Katsuno 1-1-1 Shinurashima-cho, Kanagawa-ku, Yokohama-shi, Kanagawa-ken Within Nippon Electric Robot Engineering Co., Ltd. (72) Inventor Hirofumi Matsuura Kanagawa-ku, Yokohama-shi, Kanagawa 1-1-1 Shinurashimacho 25-term F-term (reference) within NEC Robot Engineering Co., Ltd.

Claims (14)

[Claims] 1. A white line and a road edge line, or a line from a white line, a road edge line, and an alternative feature point are estimated from a captured image, and a line from three or more intersections among the estimated lines is determined. A vanishing point wherein three intersections of three lines that minimize the sum of the distances between the intersections (referred to as “most recent three intersections”) are taken out, and an average position of the three intersections is set as an estimated vanishing point. Calculation method. 2. Estimating a line from a white line, a road edge line, and an alternative feature point from a captured image, and calculating a sum of mutual distances from an intersection of the estimated line. As a penalty corresponding to the gender, minimize the sum of the mutual distances with a predetermined load applied according to the line type connecting the intersections in the order of the estimated line from the white line <road end line <alternate feature point 3 intersections ("Recent 3
A point of intersection)), and taking the average position of the three intersections as an estimated vanishing point. 3. A vanishing point calculation method characterized by estimating a vanishing point by using the method according to claim 1 or 2 when the evaluation value of the detection reliability evaluation of the white line is low. 4. When there are only three white lines, two white lines and one road end line, one white line and two road end lines, two white lines and one line from an alternative feature point, one white line and a road An evaluation is made to determine the degree of coincidence between the three lines in the order of one edge line and one line from the alternative feature point. When the first line that meets the evaluation criteria is detected, it disappears. 3. The vanishing point calculation method according to claim 1, wherein the point estimation processing is terminated. 5. A vanishing point is calculated by the vanishing point calculation method according to any one of claims 1 to 4, and a white line or a road edge line detected erroneously, and a line obtained from another alternative feature point are excluded from the estimation. A method for detecting white lines, characterized in that: 6. An inner center is used as an estimated position from the three most recent intersections according to the vanishing point calculation method according to any one of claims 1 to 4, and in re-estimation of a line, a gradient is preserved, and A white line detection method characterized by minimizing correction of an estimated position. 7. A center of gravity is used as an estimated position from the three most recent intersections according to the vanishing point calculation method according to any one of claims 1 to 4, and in line re-estimation, a line passing through the center of gravity is re-estimated. And a white line detecting method. 8. The method according to claim 1, wherein three lines having the same inclination with respect to a vertical line on the screen as three lines for calculating three intersections are not included in the index calculation. The vanishing point calculation method according to claim 1. 9. At least four lines including a white line and a road edge line, or a white line, a road edge line, and a line from an alternative feature point, based on the image capturing means and the captured image information acquired by the image capturing means. Means for estimating the three lines of the estimated lines, means for determining the intersection of three lines among the estimated lines, and how much the three lines intersect with the distance between the three intersections as an index And a means for estimating a vanishing point by obtaining an average position of the three intersections as a result of the evaluation, and estimating a vanishing point. 10. A penalty corresponding to the reliability of detection of the line when calculating the sum of mutual distances from the intersections of the three estimated lines is as follows: In the order of the estimated lines, three intersections that minimize the sum of the mutual distances applied with a predetermined load are extracted according to the type of line connecting the intersections, and the average position of the three intersections is set as an estimated vanishing point. 10. The vanishing point calculation device according to claim 9, wherein: 11. A vanishing point is obtained by the vanishing point calculating device according to claim 8 or 9, and a white line or a road edge line detected erroneously is detected.
A white line detection device, wherein a line obtained from another alternative feature point is excluded from line estimation. 12. An inner center is used as an estimated position from the three most recent intersections by the vanishing point calculation device according to claim 8 or 9,
In the line re-estimation, the inclination is preserved and the correction of the estimated position of the line is minimized. 13. A center of gravity used as an estimated position from the three most recent intersections by the vanishing point calculation device according to claim 8 or 9,
In the line re-estimation, re-estimate as a line passing through the center of gravity,
A white line detection device, characterized in that: (A) Estimating four or more lines including a white line and a road edge line, or a white line, a road edge line, and a line from an alternative feature point, from the captured image information obtained by the image capturing means. And (b) a process of obtaining mutual intersections of three lines among the estimated lines; and (c) a process of determining the degree of coincidence using the distance between the three intersections as an index.
And (d) estimating the vanishing point by calculating the average position from the three nearest intersections as a result of the evaluation, and (d) estimating the vanishing point. A recording medium on which a program for executing each of the above processes by a computer is recorded.