/// <summary>
/// Called when videoPlayer receives a new frame.
/// </summary>
/// <param name="sender"></param>
/// <param name="image"></param>
private void videoPlayer_NewFrame(object sender, ref Bitmap image)
{
// convert image to grayscale
var gray = new GrayscaleBT709();
var frame = gray.Apply(image);
// threshold image to only keep light pixels
var threshold = new Threshold(125);
threshold.ApplyInPlace(frame);
// blank out everything but the road
var horizonY = (int)(image.Height * 0.65);
var fill = new CanvasFill(new Rectangle(0, 0, image.Width, horizonY), Color.Red);
fill.ApplyInPlace(frame);
// detect edges
var edgeDetector = new CannyEdgeDetector();
edgeDetector.ApplyInPlace(frame);
// do a hough line transformation, which will search for straight lines in the frame
var transform = new HoughLineTransformation();
transform.ProcessImage(frame);
var rawLines = transform.GetMostIntensiveLines(50);
// only keep non-horizontal lines that cross the horizon at the vanishing point
var lines = from l in rawLines
let range = new Range(-75, -65)
where range.IsInside(l.Radius) &&
(l.Theta <= 85 || l.Theta >= 95)
select l;
// show the edge detection view in the bottom left box
edgeBox.Image = frame;
// show the lane detection view in the bottom right box
var laneImg = new Bitmap(image.Width, image.Height);
Utility.DrawHoughLines(lines, laneImg, Color.White, 1);
laneBox.Image = laneImg;
// draw the lanes on the main camera image too
Utility.DrawHoughLines(lines, image, Color.LightGreen, 2);
}
/// <summary>
/// Detect the highway lane boundaries.
/// </summary>
/// <param name="image">The camera frame to process</param>
/// <returns>The detected lane lines in the frame</returns>
private HoughLine[] DetectLaneLines(Bitmap image)
{
// convert image to grayscale
var frame = Grayscale.CommonAlgorithms.BT709.Apply(image);
// threshold image to only keep light pixels
var threshold = new Threshold(125);
threshold.ApplyInPlace(frame);
// blank out everything but the road
var horizonY = (int)(image.Height * 0.65);
var fill = new CanvasFill(new Rectangle(0, 0, image.Width, horizonY), Color.Red);
fill.ApplyInPlace(frame);
// detect edges
var edgeDetector = new CannyEdgeDetector();
edgeDetector.ApplyInPlace(frame);
// do a hough line transformation, which will search for straight lines in the frame
var transform = new HoughLineTransformation();
transform.ProcessImage(frame);
var rawLines = transform.GetMostIntensiveLines(50);
// only keep non-horizontal lines that cross the horizon at the vanishing point
var lines = from l in rawLines
let range = new Range(-75, -65)
where range.IsInside(l.Radius) &&
(l.Theta <= 85 || l.Theta >= 95)
select l;
// show the edge detection view in the bottom left box
edgeBox.Image = (Bitmap)frame.Clone();
// return lines
return(lines.ToArray());
}
