CN111783666A - Rapid lane line detection method based on continuous video frame corner feature matching - Google Patents
Rapid lane line detection method based on continuous video frame corner feature matching Download PDFInfo
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- G06V20/50—Context or environment of the image
- G06V20/56—Context or environment of the image exterior to a vehicle by using sensors mounted on the vehicle
- G06V20/588—Recognition of the road, e.g. of lane markings; Recognition of the vehicle driving pattern in relation to the road
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- G06V10/00—Arrangements for image or video recognition or understanding
- G06V10/20—Image preprocessing
- G06V10/25—Determination of region of interest [ROI] or a volume of interest [VOI]
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- G06V10/24—Aligning, centring, orientation detection or correction of the image
- G06V10/247—Aligning, centring, orientation detection or correction of the image by affine transforms, e.g. correction due to perspective effects; Quadrilaterals, e.g. trapezoids
Abstract
The invention relates to a rapid lane line detection method based on continuous video frame corner feature matching, which comprises the following steps: calculating an image distortion matrix; carrying out image acquisition and image correction; using a corner detection and matching method to define a dynamic region of interest, if the lane line identification result of the previous frame is failure, selecting the region of interest as a global region, and skipping the step; calculating the coordinate values of the feature point pairs of the front and rear video frames; under the condition that the lane line recognition result of the previous frame of image is true, performing optical flow estimation on points with obvious angular point characteristics in the previous frame of image, and solving coordinate values of characteristic points of the previous and next video frames by adopting a least square solution; estimating the position of a lane line in the image of the frame, and selecting and identifying an interested area; carrying out image binarization processing in the region of interest to obtain a binarized image; carrying out perspective transformation on the image; searching a lane line pixel point on the top view, and performing lane line fitting by using a polynomial equation; and (5) counting the curvature of the lane line and the lane departure distance, and marking the lane line curvature and the lane departure distance into the original image.
Description
Technical Field
The invention belongs to the technology of environment perception and image processing in intelligent vehicles, and particularly relates to a rapid lane line detection method based on continuous video frame corner feature matching.
Background
According to the statistics of the ministry of public security, 3214 thousands of motor vehicles are newly registered in 2019 nationwide, and the number of motor vehicles is kept to 3.48 hundred million. The reserved quantity of private cars firstly breaks through 2 hundred million cars, and reaches 2.07 hundred million cars. The total mileage of Chinese roads reaches 484.65 kilometers, the total mileage of express roads reaches 14.26 kilometers, and the first place in the world is. The automobile holding capacity and the total mileage of the main road are continuously increased, so that the occurrence frequency of traffic accidents is increased; meanwhile, the traffic jam degree is more dramatic due to the relatively concentrated vehicle traveling areas. According to the statistical data of the traffic administration of the ministry of public security, 238351 road traffic accidents occur in 2019 all the country, 67759 people die, 275125 people are injured, and 9.1 million yuan of direct property loss is caused. The frequent occurrence of traffic accidents endangers the life and property safety of people, causes the waste of social resources and causes serious direct and indirect economic losses.
Therefore, each country gives great support to an Intelligent Transportation System (Intelligent Transportation System), and meanwhile, enterprises and scientific research structures of each country in the world also invest a great deal of manpower and material resources to research. Among them, Intelligent Vehicles (Intelligent Vehicles) play a role as a key component of an Intelligent transportation system. The intelligent vehicle senses the environment around the vehicle in real time through sensors such as a vehicle-mounted camera and a radar, resumes a local map through an algorithm according to information obtained by the sensors, and controls the vehicle to act through an intelligent software system, so that the vehicle can run on a road more safely and reliably.
In the state of the art and due to restrictions in network transmission speed, the vehicle cannot be driven completely automatically, and many research institutes have first implemented Advanced Driver Assistance Systems (ADAS) for automobiles. The ADAS integrates the perception of the surrounding environment of the vehicle and the control of the vehicle, and realizes some basic functions of intelligent driving, specifically including the functions of automatic cruising, automatic collision prevention of the vehicle, lane departure early warning, automatic parking and the like. In many sensors of a vehicle body, a camera is widely used because it is inexpensive and contains rich color information, and is mainly used for detecting information such as lane lines, vehicles, road signs, pedestrians, and the like around a vehicle.
The current lane line identification algorithm mostly uses a Hough operator method, a linear equation fitting method and the like. The method has good practicability and can fit the position of the lane line on a straight line road, but the Hough operator method is easy to lose information of a curved road, and the linear equation fitting method needs good lane line edge characteristics as a premise and is easy to be influenced by noise due to no global constraint.
Disclosure of Invention
The invention aims to provide a rapid lane line detection method based on continuous video frame corner feature matching, which is used for solving the problems of lack of curvature information and higher complexity of the existing lane line identification method,
the invention discloses a rapid lane line detection method based on continuous video frame corner feature matching, which comprises the following steps: step 1, calculating an image distortion matrix; step 2, image acquisition and image correction are carried out; step 3, using a corner detection and matching method to define a dynamic region of interest, comprising: if the lane line identification result of the previous frame is failure, selecting the region of interest as the global region, and skipping the step 3; calculating the coordinate values of the feature point pairs of the front and rear video frames; under the condition that the lane line recognition result of the previous frame of image is true, performing optical flow estimation on points with obvious angular point characteristics in the previous frame of image, and solving coordinate values of characteristic points of the previous and next video frames by adopting a least square solution; estimating the position of a lane line in the image of the frame, and selecting and identifying an interested area; step 4, carrying out image binarization processing in the region of interest to obtain a binarized image; step 5, carrying out perspective transformation on the image to obtain a top view; step 6, searching lane line pixel points on the top view, and performing lane line fitting by using a polynomial equation; step 7, counting lane line curvature and lane departure distance, and marking the lane line curvature and the lane departure distance into an original image; and 8, repeating the steps 2 to 6 until the image acquisition fails or a termination identification signal is received.
The invention provides a rapid lane line detection method based on continuous video frame corner point feature matching, wherein corner points, namely intersection points between outlines have the feature of stable property for the same scene even if the visual angle changes. The corner points can effectively reduce the data volume of the information while keeping the important characteristics of the image graph, so that the content of the information is high, the calculation speed is effectively improved, the reliable matching of the image is facilitated, and the real-time processing becomes possible.
Drawings
FIG. 1 is a flow chart of a method according to the present invention;
FIG. 2 is a distortion corrected image;
FIG. 3 is a grayed and binarized image;
FIG. 4 is a perspective transformed image;
FIG. 5 is an image after lane line fitting;
FIG. 6 is an annotated image.
Detailed Description
In order to make the objects, contents, and advantages of the present invention clearer, the following detailed description of the embodiments of the present invention will be made in conjunction with the accompanying drawings and examples.
FIG. 1 is a flow chart of a method according to the present invention; FIG. 2 is a distortion corrected image; FIG. 3 is a grayed and binarized image; FIG. 4 is a perspective transformed image; FIG. 5 is an image after lane line fitting; fig. 6 is an annotated image, and as shown in fig. 1 to 6, the method for detecting a fast lane line based on feature matching of corner points of continuous video frames of the present invention includes the following steps:
step 1, calculating an image distortion matrix
Distortion is introduced due to variations in the camera lens during manufacturing and assembly, resulting in distortion of the original image captured. Therefore, during the use process, the acquired image needs to be corrected in a calibration mode.
Step 1.1, shooting images by using an interface provided by a camera drive, and shooting chessboard calibration images from 20 different angles
Step 1.2, graying the image by using a weighted average method
And step 1.3, searching the inner corner points of the calibration plate in the gray level image and calculating a distortion matrix by using a Zhang-Zhengyou calibration method.
Step 2, image acquisition and image correction
At the beginning of each frame of image processing period, it is first determined whether the current processing period is the primary processing, and if the current processing period is the primary planning, the lane line identification result of the previous frame is marked as False.
An interface provided by a camera drive is called to collect an image in front of the vehicle, and a distortion matrix is used to perform distortion correction on the collected image to obtain a corrected image, as shown in fig. 2.
Step 3, using the corner point detection and matching method to define the dynamic Region of interest (ROI)
Step 3.1, if the lane line identification result of the previous frame is False, the region of interest is selected as the global region, and the step 3 is skipped
Step 3.2, the coordinate values of the characteristic point pairs of the front and the rear video frames are obtained
And under the condition that the lane line recognition result of the previous frame of image is True, performing optical flow estimation on the points with obvious angular point features in the previous frame of image by using an L-K method, wherein the equation of the optical flow estimation is an overdetermined linear equation, and multiple groups of coordinate values of the feature point pairs of the previous and next video frames are obtained by adopting a least square solution.
Step 3.3, the position of the lane line in the image of the frame is estimated, and the region of interest is selected and identified
Step 3.3.1, dividing the coordinate values of the characteristic point pairs into a left group and a right group according to the position of the coordinate in the image relative to a central vertical line
Step 3.3.2, removing foreground pixels
And (3) aiming at the left and right groups of coordinate points, respectively using a DBSCAN clustering algorithm to the coordinate point displacement vectors, and eliminating foreground pixels to obtain main background coordinate points.
Step 3.3.3, solving the relative displacement vector of the front background image by using a weighted mean method
Step 3.3.4, setting the region of interest
Using the derived displacement vector
Respectively calculating estimated curves of the left lane and the right lane, and setting a sliding window with the left width b (b being 50) of the estimated curves as an interested area.
Step 4, carrying out image binarization processing in the region of interest to obtain a binarized image
Step 4.1, carrying out gray processing on the image by using a composite operator
Wherein the Sobel operator calculation method comprises
Where Gx and Gy are the horizontal and vertical edge detected images respectively,
for the planar convolution operation, A is the original image.
The formula for calculating the amplitude and gradient direction of the Sobel operator is as follows:
wherein G and theta are respectively the amplitude and the gradient direction corresponding to the pixel points.
Step 4.1.1, graying the image by using a Sobel operator in the horizontal direction, namely obtaining a Gx corresponding image
Step 4.1.2, graying the image by using a Sobel operator on the amplitude value, namely obtaining the image corresponding to G
Step 4.1.3, performing graying on the image by using a Sobel operator in the gradient direction to obtain a theta corresponding image
Step 4.1.4, taking image saturation channel component
The Hue (Hue), Saturation (Saturation), and luminance (brightness) channel components of an image in the HSL color space are separated, and the Saturation channel component is taken.
And 4.2, averaging the four gray level images to obtain a gray level image of the composite operator, as shown in FIG. 3.
And 5, carrying out perspective transformation on the image to obtain a top view. As shown in fig. 4.
Step 6, finding the lane line pixel points on the top view, and carrying out lane line fitting by using a polynomial equation
Step 6.1, searching the pixel points of the lane lines
Step 6.1.1, calculating the histogram of the image at the lower half part, and counting the peak positions of the histogram at the left side and the right side
Step 6.1.2, segmenting the image
The image is horizontally divided into 9 equal parts, and a rectangular sliding window with the same height of two slices and the width of 200 pixels is used in the bottom slice to cover the left and right peak positions of the histogram.
Step 6.1.3, searching for lane line pixel points
And moving the sliding window from bottom to top, sequentially searching the lane line pixel points in each slice, and repositioning the center of the sliding rectangle in the upper slice.
Step 6.2, second order polynomial fitting Using least squares
And respectively carrying out second-order polynomial fitting on the left and right groups of lane line pixel points by using a least square method to obtain a lane line equation under perspective transformation. Equation of lane line
The formula of (1) is:
wherein the polynomial coefficient a0、a1、a2Is calculated as
Wherein x isiAnd yiAnd 6.1.3, the horizontal and vertical coordinates of the ith group of lane line pixel points searched in the step.
The position of the fitted lane line in the image is shown in fig. 5.
Step 6.3, counting the pixel point parameters of the lane lines and marking the recognition status bits of the lane lines
When the number of pixels is less than the set threshold value 200 or the curvature and the range of the fitted curve exceed the threshold value range, the detection is considered to be failed, the lane line identification state bit is marked as False (the next frame uses global detection through marking), and the detection result of the previous frame of video is used in the current frame; otherwise, marking the lane line identification state bit as True.
Step 7, counting the curvature of the lane line and the lane departure distance, and marking the information into the original image
And 7.1, calculating the curvature of the lane, and converting the unit into meters according to the corresponding relation.
And 7.2, calculating the lane departure distance, and converting the unit into meters according to the corresponding relation.
And 7.3, information labeling.
And marking left and right lane lines on a blank image which is as high as the image after perspective transformation and has the same width as the image, and greening the middle area of the blank image. And fusing the image after inverse perspective transformation with the original image, and finally marking the curvature of the lane line and the lane departure distance to the upper left part of the image by characters. The annotated image is shown in fig. 6.
Step 8, repeating the steps 2 to 6 until the image acquisition fails or the termination identification signal is received
The invention provides another embodiment of a rapid lane line detection method based on continuous video frame corner feature matching, which comprises the following steps:
step 1, calculating an image distortion matrix
Distortion is introduced due to variations in the camera lens during manufacturing and assembly, resulting in distortion of the original image. Therefore, during the use process, the acquired image needs to be corrected.
Step 1.1, shooting chessboard calibration images from 20 different angles by using an interface provided by a camera drive
Step 1.2, graying the image by using a weighted average method
f(i,j)＝0.3*R(i,j)+0.59*G(i,j)+0.11*B(i,j)
Wherein f (i, j) is the gray value corresponding to the pixel point with the coordinate (i, j) after graying, and R (i, j), G (i, j), and B (i, j) are the red, green, and blue channel components of the pixel point with the coordinate (i, j) in the color image, respectively.
Step 1.3, searching inner angular points of a calibration plate in the gray level image and calculating a distortion matrix by using a Zhang-Yongyou calibration method
Step 2, image acquisition and image correction
At the beginning of each frame of image processing period, it is first determined whether the current processing period is the primary processing, and if the current processing period is the primary planning, the lane line identification result of the previous frame is marked as False.
An interface provided by a camera drive is called to collect an image in front of the vehicle, and a distortion matrix is used to perform distortion correction on the collected image to obtain a corrected image, as shown in fig. 2.
Step 3, using the corner point detection and matching method to define the dynamic Region of interest (ROI)
Step 3.1, if the lane line identification result of the previous frame is False, the region of interest is selected as the global region, and the step is skipped
Step 3.2, carry on the light stream estimation, solve the least square solution
Under the condition that the result of recognizing the lane lines in the previous frame of image is True, performing optical flow estimation on points with remarkable angular point characteristics in the previous frame of image by using an L-K method, wherein the equation of the optical flow estimation is an overdetermined linear equation and adopts least square solution as follows:
wherein u and v are relative displacement coordinates of the feature points between the video frames, and the calculation method of each symbol is as follows:
after calculation, a plurality of groups of coordinate values of the feature point pairs of the front and rear video frames are obtained.
Step 3.3, the position of the lane line in the image of the frame is estimated, and the region of interest is selected and identified
Step 3.3.1, dividing the coordinate values of the characteristic point pairs into a left group and a right group according to the position of the coordinate in the image relative to a central vertical line
Step 3.3.2, removing foreground pixels
And (3) aiming at the left and right groups of coordinate points, respectively using a DBSCAN clustering algorithm to the coordinate point displacement vectors, and eliminating foreground pixels to obtain main background coordinate points.
Step 3.3.3, solving the relative displacement vector of the front background image
Using a weighted mean method to solve the relative displacement vector of the front background image, wherein the calculation formula is as follows:
wherein
The obtained relative displacement vector of the front background image is the relative displacement vector of the ith group of characteristic pixel points, and the weight is the reciprocal distance of the ith characteristic pixel point and a lane fitting curve.
Step 3.3.4, setting the region of interest
Using the derived displacement vector
Respectively calculating estimated curves of the left lane and the right lane, and setting a sliding window with the left width b (b being 50) of the estimated curves as an interested area.
Step 4, carrying out image binarization processing in the region of interest to obtain a binarized image
Step 4.1, carrying out gray processing on the image by using a composite operator
Wherein the Sobel operator calculation method comprises
Where Gx and Gy are the horizontal and vertical edge detected images respectively,
for the planar convolution operation, A is the original image.
The formula for calculating the amplitude and gradient direction of the Sobel operator is as follows:
wherein G and theta are respectively the amplitude and the gradient direction corresponding to the pixel points.
Step 4.1.1, graying the image by using a Sobel operator in the horizontal direction, namely obtaining a Gx corresponding image
Step 4.1.2, graying the image by using a Sobel operator on the amplitude value, namely obtaining the image corresponding to G
Step 4.1.3, performing graying on the image by using a Sobel operator in the gradient direction to obtain a theta corresponding image
Step 4.1.4, separating image saturation channel components
The Hue (Hue), Saturation (Saturation), and luminance (brightness) channel components of an image in the HSL color space are separated, and the Saturation channel component is taken.
Step 4.2, averaging the four gray level images to obtain a gray level image of the composite operator, as shown in fig. 3
And 5, carrying out perspective transformation on the image to obtain a top view. As shown in fig. 4
Step 6, finding the lane line pixel points on the top view, and carrying out lane line fitting by using a polynomial equation
Step 6.1, searching the pixel points of the lane lines
Step 6.1.1, calculating the histogram of the image at the lower half part, and counting the peak positions of the histogram at the left side and the right side
Step 6.1.2, horizontally dividing the image into 9 equal parts, using a rectangular sliding window with two slices being equal in height and 200 pixels in width in the bottom slice, and covering the left and right peak positions of the histogram
Step 6.1.3, moving the sliding window from bottom to top, sequentially searching the lane line pixel points in each slice, and repositioning the center of the sliding rectangle in the upper slice
Step 6.2, performing second-order polynomial fitting
Respectively carrying out second-order polynomial fitting on the left and right groups of lane line pixel points by using a least square method to obtain a lane line equation under perspective transformation
Is of the formula
Wherein the polynomial coefficient a0、a1、a2Is calculated as
Wherein x isiAnd yiAnd 6.1.3, the horizontal and vertical coordinates of the ith group of lane line pixel points searched in the step.
The position of the fitted lane line in the image is shown in fig. 5.
Step 6.3, counting the pixel point parameters of the lane lines and marking the recognition status bits of the lane lines
When the number of pixels is less than the set threshold value 200 or the curvature and the range of the fitted curve exceed the threshold value range, the detection is considered to be failed, the lane line identification state bit is marked as False (the next frame uses global detection through marking), and the detection result of the previous frame of video is used in the current frame; otherwise, marking the lane line identification state bit as True.
Step 7, counting the curvature of the lane line and the lane departure distance, and marking the information into the original image
Step 7.1, calculating lane curvature
Respectively counting the curvature mean value of the lane line corresponding to each vertical coordinate in the next half image according to a fitting equation of the left lane line and the right lane line, converting a unit into meters according to the corresponding relation of 3.7 meters/700 pixels in the horizontal direction and 30 meters/720 pixels in the vertical direction, and calculating the mean value of the left average curvature and the right average curvature.
Step 7.2, calculating the lane departure distance
And according to a fitting equation of the left lane line and the right lane line, counting the difference value between the central position of the left lane line and the central position of the right lane line corresponding to each vertical coordinate pixel in the lower half image and the transverse center of the image, and converting the unit into meters according to the corresponding relation of 3.7 meters/700 pixels in the horizontal direction.
Step 7.3, information labeling
And marking left and right lane lines on a blank image which is as high as the image after perspective transformation and has the same width as the image, and greening the middle area of the blank image. And fusing the image after inverse perspective transformation with the original image, and finally marking the curvature of the lane line and the lane departure distance to the upper left part of the image by characters. The annotated image is shown in fig. 6.
Step 8, repeating the steps 2 to 6 until the image acquisition fails or the termination identification signal is received
The invention provides a rapid lane line detection method based on continuous video frame corner feature matching, which is mainly used for lane line identification application in auxiliary driving and automatic driving. The method detects the relative movement of the background in front of the vehicle by introducing a continuous video frame corner matching method, and dynamically pre-estimates the range of the lane line according to the time correlation between video frames to reduce the Region of interest (ROI). Then, the image is subjected to combined graying and binarization processing. And finally, carrying out perspective transformation on the image, searching the lane line pixel points and carrying out lane line fitting by using a second-order polynomial equation.
Aiming at the problems that the existing lane line identification method is lack of curvature information and high in complexity, the invention provides a rapid lane line detection method based on continuous video frame corner point feature matching, wherein corner points, namely intersection points between outlines have the feature of stable property for the same scene even if the visual angle changes. The corner points can effectively reduce the data volume of the information while keeping the important characteristics of the image graph, so that the content of the information is high, the calculation speed is effectively improved, the reliable matching of the image is facilitated, and the real-time processing becomes possible.
The above description is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, several modifications and variations can be made without departing from the technical principle of the present invention, and these modifications and variations should also be regarded as the protection scope of the present invention.
Claims (10)
1. A rapid lane line detection method based on continuous video frame corner feature matching comprises the following steps:
step 1, calculating an image distortion matrix;
step 2, image acquisition and image correction are carried out;
step 3, using a corner detection and matching method to define a dynamic region of interest, comprising:
if the lane line identification result of the previous frame is failure, selecting the region of interest as the global region, and skipping the step 3;
calculating the coordinate values of the feature point pairs of the front and rear video frames;
under the condition that the lane line recognition result of the previous frame of image is true, performing optical flow estimation on points with obvious angular point characteristics in the previous frame of image, and solving coordinate values of characteristic points of the previous and next video frames by adopting a least square solution;
estimating the position of a lane line in the image of the frame, and selecting and identifying an interested area;
step 4, carrying out image binarization processing in the region of interest to obtain a binarized image;
step 5, carrying out perspective transformation on the image to obtain a top view;
step 6, searching lane line pixel points on the top view, and performing lane line fitting by using a polynomial equation;
step 7, counting lane line curvature and lane departure distance, and marking the lane line curvature and the lane departure distance into an original image;
and 8, repeating the steps 2 to 6 until the image acquisition fails or a termination identification signal is received.
2. The fast lane-line detection method based on corner feature matching of continuous video frames as claimed in claim 1, wherein the step 1, calculating the image distortion matrix comprises:
shooting images by using an interface provided by a camera drive, and shooting chessboard calibration images from 20 different angles;
graying the image by using a weighted average method;
and searching the inner angular points of the calibration plate in the gray-scale image and calculating a distortion matrix by using a Zhang-friend calibration method.
3. The fast lane line detection method based on corner feature matching of continuous video frames as claimed in claim 1, wherein the step 2 of image acquisition and image correction comprises:
starting each frame of image processing period, determining whether the current processing period is primary processing, and if the current processing period is primary planning, marking the lane line identification result of the previous frame as failure;
and calling an interface provided by a camera drive to acquire an image in front of the vehicle, and performing distortion correction on the acquired image by using a distortion matrix to obtain a corrected image.
4. The method of claim 1, wherein the removing foreground pixels comprises:
and (3) for the left and right groups of coordinate points, respectively using a DBSCAN clustering algorithm for the coordinate point displacement vectors, and eliminating foreground pixels to obtain main background coordinate points.
5. The method as claimed in claim 1, wherein the step of predicting the position of the lane line in the current frame image and the step of selecting the region of interest includes:
dividing the coordinate values of the feature point pairs into a left group and a right group according to the position of the coordinate in the image relative to a middle vertical line;
removing foreground pixels to obtain main background coordinate points;
solving a relative displacement vector of the front background image by using a weighted mean method;
setting a region of interest;
using the derived displacement vector
Respectively calculating the pre-estimated curves of the left lane and the right lane, setting the left width and the right width of the pre-estimated curves as b, and setting a sliding window as an interested area.
6. The fast lane-line detection method based on corner feature matching of continuous video frames as claimed in claim 1, wherein step 4 comprises:
the calculation method of the Sobel operator comprises the following steps:
where Gx and Gy are horizontal and vertical edge detected images respectively,
a is a plane convolution operation, and A is an original image;
the formula for calculating the amplitude and gradient direction of the Sobel operator is as follows:
g and theta are respectively the amplitude and the gradient direction corresponding to the pixel points;
graying the image by using a Sobel operator in the horizontal direction to obtain a Gx corresponding image;
graying the image by using a Sobel operator on the amplitude value to obtain a G corresponding image;
graying the image by using Sobel operator in the gradient direction, namely obtaining a theta corresponding image
Taking an image saturation channel component;
and obtaining a gray level image of the composite operator.
7. The fast lane line detection method based on feature matching of corner points of continuous video frames as claimed in claim 1, wherein step 6 specifically comprises:
find the lane line pixel, include:
calculating a histogram of the image at the lower half part, and counting the peak positions of the histogram at the left side and the right side;
dividing the image into 9 equal parts horizontally, using two rectangular sliding windows with the same height and 200 pixel width in the bottom slice, and covering the left and right peak positions of the histogram;
moving the sliding window from bottom to top, sequentially searching lane line pixel points in each slice, and repositioning the center of a sliding rectangle in the upper slice;
performing second-order polynomial fitting by using a least square method;
counting the pixel point parameters of the lane lines, marking the recognition status bits of the lane lines as failure when the pixel points are less than a set threshold value 200 or the curvature and the range of a fitting curve exceed the range of the threshold value, and using the detection result of the previous frame of video in the current frame; otherwise, marking the lane line identification state bit as successful.
8. The fast lane line detection method based on feature matching of corner points of continuous video frames as claimed in claim 1, wherein step 7 specifically comprises:
calculating lane curvature, and converting the unit into meter according to the corresponding relation;
calculating lane departure distance, and converting the unit into meters according to the corresponding relation;
marking left and right lane lines on a blank image which has the same height and the same width with the image after perspective transformation, greening the middle area of the blank image, fusing the image with the original image after inverse perspective transformation, and marking the curvature of the lane lines and the lane departure distance on the image by characters.
9. The fast lane line detection method based on corner feature matching of continuous video frames as claimed in claim 7, wherein the performing of second order polynomial fitting using least squares method comprises:
respectively carrying out second-order polynomial fitting on the left and right groups of lane line pixel points by using a least square method to obtain a lane line equation under perspective transformation
The formula of (1) is:
wherein the polynomial coefficient a0、a1And a2The calculation equation of (a) is:
wherein x isiAnd yiThe horizontal and vertical coordinates of the searched ith group of lane line pixel points in the lane line pixel points in each slice are searched.
10. The fast lane detection method based on corner feature matching of successive video frames as claimed in claim 1,
step 3, optical flow estimation is carried out, and the least square solution solving comprises the following steps:
wherein u and v are relative displacement coordinates of the feature points between the video frames, and the calculation method of each symbol is as follows:
after calculation, a plurality of groups of characteristic point pair coordinate values of the front and rear video frames are obtained.
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