In this project, you will use the tools you learned about in the lesson to identify lane lines on the road. You can develop your pipeline on a series of individual images, and later apply the result to a video stream (really just a series of images). Check out the video clip "raw-lines-example.mp4" (also contained in this repository) to see what the output should look like after using the helper functions below.
Once you have a result that looks roughly like "raw-lines-example.mp4", you'll need to get creative and try to average and/or extrapolate the line segments you've detected to map out the full extent of the lane lines. You can see an example of the result you're going for in the video "P1_example.mp4". Ultimately, you would like to draw just one line for the left side of the lane, and one for the right.
Let's have a look at our first image called 'test_images/solidWhiteRight.jpg'. Run the 2 cells below (hit Shift-Enter or the "play" button above) to display the image.
Note: If, at any point, you encounter frozen display windows or other confounding issues, you can always start again with a clean slate by going to the "Kernel" menu above and selecting "Restart & Clear Output".
The tools you have are color selection, region of interest selection, grayscaling, Gaussian smoothing, Canny Edge Detection and Hough Tranform line detection. You are also free to explore and try other techniques that were not presented in the lesson. Your goal is piece together a pipeline to detect the line segments in the image, then average/extrapolate them and draw them onto the image for display (as below). Once you have a working pipeline, try it out on the video stream below.
Your output should look something like this (above) after detecting line segments using the helper functions below
Your goal is to connect/average/extrapolate line segments to get output like this
Run the cell below to import some packages. If you get an import error for a package you've already installed, try changing your kernel (select the Kernel menu above --> Change Kernel). Still have problems? Try relaunching Jupyter Notebook from the terminal prompt. Also, see this forum post for more troubleshooting tips.
In [1]:
#importing some useful packages
import matplotlib.pyplot as plt
import matplotlib.image as mpimg
import numpy as np
import cv2
%matplotlib inline
In [2]:
#reading in an image
image = mpimg.imread('test_images/solidWhiteRight.jpg')
#printing out some stats and plotting
print('This image is:', type(image), 'with dimesions:', image.shape)
plt.imshow(image) # if you wanted to show a single color channel image called 'gray', for example, call as plt.imshow(gray, cmap='gray')
Out[2]:
Some OpenCV functions (beyond those introduced in the lesson) that might be useful for this project are:
cv2.inRange() for color selection
cv2.fillPoly() for regions selection
cv2.line() to draw lines on an image given endpoints
cv2.addWeighted() to coadd / overlay two images
cv2.cvtColor() to grayscale or change color
cv2.imwrite() to output images to file
cv2.bitwise_and() to apply a mask to an image
Check out the OpenCV documentation to learn about these and discover even more awesome functionality!
Below are some helper functions to help get you started. They should look familiar from the lesson!
In [3]:
import math
GREEN = [0, 255, 0]
def grayscale(img):
"""Applies the Grayscale transform
This will return an image with only one color channel
but NOTE: to see the returned image as grayscale
(assuming your grayscaled image is called 'gray')
you should call plt.imshow(gray, cmap='gray')"""
return cv2.cvtColor(img, cv2.COLOR_RGB2GRAY)
# Or use BGR2GRAY if you read an image with cv2.imread()
# return cv2.cvtColor(img, cv2.COLOR_BGR2GRAY)
def canny(img, low_threshold, high_threshold):
"""Applies the Canny transform"""
return cv2.Canny(img, low_threshold, high_threshold)
def gaussian_blur(img, kernel_size):
"""Applies a Gaussian Noise kernel"""
return cv2.GaussianBlur(img, (kernel_size, kernel_size), 0)
def region_of_interest(img, vertices):
"""
Applies an image mask.
Only keeps the region of the image defined by the polygon
formed from `vertices`. The rest of the image is set to black.
"""
#defining a blank mask to start with
mask = np.zeros_like(img)
#defining a 3 channel or 1 channel color to fill the mask with depending on the input image
if len(img.shape) > 2:
channel_count = img.shape[2] # i.e. 3 or 4 depending on your image
ignore_mask_color = (255,) * channel_count
else:
ignore_mask_color = 255
#filling pixels inside the polygon defined by "vertices" with the fill color
cv2.fillPoly(mask, vertices, ignore_mask_color)
#returning the image only where mask pixels are nonzero
masked_image = cv2.bitwise_and(img, mask)
return masked_image
def draw_lines(img, lines, color=[255, 0, 0], thickness=2):
"""
NOTE: this is the function you might want to use as a starting point once you want to
average/extrapolate the line segments you detect to map out the full
extent of the lane (going from the result shown in raw-lines-example.mp4
to that shown in P1_example.mp4).
Think about things like separating line segments by their
slope ((y2-y1)/(x2-x1)) to decide which segments are part of the left
line vs. the right line. Then, you can average the position of each of
the lines and extrapolate to the top and bottom of the lane.
This function draws `lines` with `color` and `thickness`.
Lines are drawn on the image inplace (mutates the image).
If you want to make the lines semi-transparent, think about combining
this function with the weighted_img() function below
"""
for line in lines:
for x1,y1,x2,y2 in line:
cv2.line(img, (x1, y1), (x2, y2), color, thickness)
def hough_lines(img, rho, theta, threshold, min_line_len, max_line_gap):
"""
`img` should be the output of a Canny transform.
Returns an image with hough lines drawn.
"""
lines = cv2.HoughLinesP(img, rho, theta, threshold, np.array([]), minLineLength=min_line_len, maxLineGap=max_line_gap)
line_img = np.zeros((img.shape[0], img.shape[1], 3), dtype=np.uint8)
if (lines is not None):
draw_extrapolated_lines(line_img, lines)
if (DEBUG):
draw_lines(line_img, lines, GREEN)
return line_img
# Python 3 has support for cool math symbols.
def weighted_img(img, initial_img, α=0.8, β=1., λ=0.):
"""
`img` is the output of the hough_lines(), An image with lines drawn on it.
Should be a blank image (all black) with lines drawn on it.
`initial_img` should be the image before any processing.
The result image is computed as follows:
initial_img * α + img * β + λ
NOTE: initial_img and img must be the same shape!
"""
return cv2.addWeighted(initial_img, α, img, β, λ)
In [4]:
import os
test_images = os.listdir("test_images/")
run your solution on all test_images and make copies into the test_images directory).
In [5]:
DEBUG = True # draw debug lines over the image
LOGGING = False # print some logging variables
WHITE = (255, 255, 255)
BLACK = (0, 0, 0)
BLUE = (0, 0, 255)
GAUSSIAN_KERNEL_SIZE = 5
CANNY_LOW_THRESHOLD = 50
CANNY_HIGH_THRESHOLD = 150
HOUGH_RHO = 2 # distance resolution in pixels of the Hough grid
HOUGH_THETA = np.pi/180 # angular resolution in radians of the Hough grid
HOUGH_THRESHOLD = 15 # minimum number of votes (intersections in Hough grid cell)
HOUGH_MIN_LINE_LENGTH = 40 #minimum number of pixels making up a line
HOUGH_MAX_LINE_GAP = 20 # maximum gap in pixels between connectable line segments
VERTICES_TOP_RATIO = 0.6
VERTICES_EDGE_RATIO = 0.45 # 0.443
VERTICES_INSET_RATIO = 0.9
VERTICES_X_INSET = 50
def show(images):
for image in images:
plt.imshow(image)
#plt.imshow(image, cmap='Greys_r')
plt.show()
def load_image(image_file):
image = mpimg.imread('test_images/' + image_file)
return image
def save_image(image, name):
mpimg.imsave('processed-images/' + name, image)
def go_go_gadget(original_image):
shape = original_image.shape
width = shape[1]
height = shape[0]
x_half = width / 2
y_start = height * VERTICES_TOP_RATIO
bottom = height * VERTICES_INSET_RATIO
if (LOGGING):
print("left: {}".format(width * VERTICES_EDGE_RATIO))
print("right: {}".format(width * (1 - VERTICES_EDGE_RATIO)))
print("bottom: {}".format(height))
left_vertices = np.array([[
(VERTICES_X_INSET, bottom),(width * VERTICES_EDGE_RATIO, y_start),
(x_half, y_start), (x_half, bottom)
]], dtype=np.int32)
right_vertices = np.array([[
(x_half, bottom),(x_half, y_start),
(width * (1 - VERTICES_EDGE_RATIO), y_start), (width - VERTICES_X_INSET, bottom)
]], dtype=np.int32)
image = grayscale(original_image)
image = gaussian_blur(image, GAUSSIAN_KERNEL_SIZE)
image = canny(image, CANNY_LOW_THRESHOLD, CANNY_HIGH_THRESHOLD)
left_image = region_of_interest(image, left_vertices)
left_image = hough_lines(left_image, HOUGH_RHO, HOUGH_THETA, HOUGH_THRESHOLD, HOUGH_MIN_LINE_LENGTH, HOUGH_MAX_LINE_GAP)
left_image = weighted_img(left_image, original_image)
right_image = region_of_interest(image, right_vertices)
right_image = hough_lines(right_image, HOUGH_RHO, HOUGH_THETA, HOUGH_THRESHOLD, HOUGH_MIN_LINE_LENGTH, HOUGH_MAX_LINE_GAP)
image = weighted_img(right_image, left_image)
if (DEBUG):
image = cv2.polylines(image, left_vertices, 1, WHITE, 2)
image = cv2.polylines(image, right_vertices, 1, BLACK, 2)
return image
def draw_extrapolated_lines(image, lines, color=[255, 0, 0], thickness=15):
shape = image.shape
width = shape[1]
height = shape[0]
x_array = np.array([])
y_array = np.array([])
for line in lines:
for x1,y1,x2,y2 in line:
x_array= np.append(x_array, [x1, x2])
y_array =np.append(y_array, [y1, y2])
x_coefficients = np.polyfit(x_array, y_array, 1)
y_coefficients = np.polyfit(y_array, x_array, 1)
fy = np.poly1d(x_coefficients)
fx = np.poly1d(y_coefficients)
x1 = int(min(x_array))
y1 = int(fy(min(x_array)))
x2 = int(max(x_array))
y2 = int(fy(max(x_array)))
bottom_x1 = int(fx(height))
bottom_y1 = height
bottom_x2 = x2 if x_coefficients[0] < 0 else x1
bottom_y2 = y2 if x_coefficients[0] < 0 else y1
if (LOGGING):
print(shape)
print("line: ({},{}) ({},{})".format(x1, y1, x2, y2))
print("line ext: ({},{}) ({},{})".format(bottom_x1, bottom_y1, bottom_x2, bottom_y2))
cv2.line(image,(bottom_x1, bottom_y1),(bottom_x2, bottom_y2), color, thickness)
if (DEBUG):
cv2.line(image,(x1, y1),(x2, y2), BLUE, thickness)
images = [load_image(image) for image in test_images]
images = [go_go_gadget(image) for image in images]
#images = [go_go_gadget(images[1])]
[save_image(image, name) for image, name in zip(images, test_images)]
show(images)
You know what's cooler than drawing lanes over images? Drawing lanes over video!
We can test our solution on two provided videos:
solidWhiteRight.mp4
solidYellowLeft.mp4
Note: if you get an import error when you run the next cell, try changing your kernel (select the Kernel menu above --> Change Kernel). Still have problems? Try relaunching Jupyter Notebook from the terminal prompt. Also, check out this forum post for more troubleshooting tips.
If you get an error that looks like this:
NeedDownloadError: Need ffmpeg exe.
You can download it by calling:
imageio.plugins.ffmpeg.download()Follow the instructions in the error message and check out this forum post for more troubleshooting tips across operating systems.
In [6]:
# Import everything needed to edit/save/watch video clips
from moviepy.editor import VideoFileClip
from IPython.display import HTML
In [7]:
def process_image(image):
# NOTE: The output you return should be a color image (3 channel) for processing video below
# TODO: put your pipeline here,
# you should return the final output (image with lines are drawn on lanes)
result = go_go_gadget(image)
return result
Let's try the one with the solid white lane on the right first ...
In [8]:
LOGGING = False
DEBUG = False
white_output = 'white.mp4'
clip1 = VideoFileClip("solidWhiteRight.mp4")
white_clip = clip1.fl_image(process_image) #NOTE: this function expects color images!!
%time white_clip.write_videofile(white_output, audio=False)
Play the video inline, or if you prefer find the video in your filesystem (should be in the same directory) and play it in your video player of choice.
In [9]:
HTML("""
<video width="960" height="540" controls>
<source src="{0}">
</video>
""".format(white_output))
Out[9]:
At this point, if you were successful you probably have the Hough line segments drawn onto the road, but what about identifying the full extent of the lane and marking it clearly as in the example video (P1_example.mp4)? Think about defining a line to run the full length of the visible lane based on the line segments you identified with the Hough Transform. Modify your draw_lines function accordingly and try re-running your pipeline.
Now for the one with the solid yellow lane on the left. This one's more tricky!
In [10]:
LOGGING = False
DEBUG = False
yellow_output = 'yellow.mp4'
clip2 = VideoFileClip('solidYellowLeft.mp4')
yellow_clip = clip2.fl_image(process_image)
%time yellow_clip.write_videofile(yellow_output, audio=False)
In [11]:
HTML("""
<video width="960" height="540" controls>
<source src="{0}">
</video>
""".format(yellow_output))
Out[11]:
Congratulations on finding the lane lines! As the final step in this project, we would like you to share your thoughts on your lane finding pipeline... specifically, how could you imagine making your algorithm better / more robust? Where will your current algorithm be likely to fail?
Please add your thoughts below, and if you're up for making your pipeline more robust, be sure to scroll down and check out the optional challenge video below!
I was about to start calculating all the lines/slopes manually by looping through all of the Hough line segments, but luckily I came accross this forum post which clued me in to Numpy's polyfit and poly1d methods. The algorithm could be made better by figuring out some way to clean up some of the line-noise which comes up every once in a while. Perhaps by removing the outlier lines/points or tweaking the Canny settings, or both. The settings for which areas to look for lines for could probably also be tweaked in a way that they're more intelligent and auto-detect the polygon areas in which to look for lines.
The inability of the current method to filter out outlier lines is probably the main reason it fails at reliably detecting/drawing the lines in the challenge video.
In [12]:
LOGGING = False
DEBUG = True
challenge_output = 'extra.mp4'
clip2 = VideoFileClip('challenge.mp4')
challenge_clip = clip2.fl_image(process_image)
%time challenge_clip.write_videofile(challenge_output, audio=False)
In [13]:
HTML("""
<video width="960" height="540" controls>
<source src="{0}">
</video>
""".format(challenge_output))
Out[13]:
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