Function test2DLineFitting

examples/cpp_example.cpp:704–850

An example function showing how to fit calculate a 2D line to a set of 2D points by Graph-Cut RANSAC

// An example function showing how to fit calculate a 2D line to a set of 2D points by Graph-Cut RANSAC
void test2DLineFitting(
	const std::string& image_path_, // The path where the ground truth pose can be found
	const double confidence_, // The RANSAC confidence value
	const double inlier_outlier_threshold_, // The used inlier-outlier threshold in GC-RANSAC.
	const double spatial_coherence_weight_, // The weight of the spatial coherence term in the graph-cut energy minimization.
	const double sphere_radius_,  // The radius of the sphere used for determining the neighborhood-graph
	const double minimum_inlier_ratio_for_sprt_) // An assumption about the minimum inlier ratio used for the SPRT test
{
	// Load the image
	cv::Mat image = cv::imread(image_path_),
		image_gray;

	// Checking if the image has been loaded
	if (image.empty())
	{
		fprintf(stderr, "Image '%s' has not been loaded correctly.\n", image_path_.c_str());
		return;
	}

	// Applying Canny edge detection
	constexpr double
		low_threshold = 50,
		max_low_threshold = 100,
		kernel_size = 3,
		ratio = 3;

	cv::Mat detected_edges;
	cv::cvtColor(image, image_gray, cv::COLOR_BGR2GRAY);
	cv::blur(image_gray, detected_edges, cv::Size(3, 3));

	cv::Canny(detected_edges,
		detected_edges,
		low_threshold,
		low_threshold * ratio,
		kernel_size);

	// Storing the points for line fitting
	cv::Mat points(0, 2, CV_64F),
		point(1, 2, CV_64F);
	for (size_t row = 0; row < detected_edges.rows; row += 1)
		for (size_t col = 0; col < detected_edges.cols; col += 1)
			if (detected_edges.at<uchar>(row, col) > std::numeric_limits<int>::epsilon())
			{
				point.at<double>(0) = col;
				point.at<double>(1) = row;
				points.push_back(point);
			}

	// Initialize the neighborhood used in Graph-cut RANSAC and, perhaps,
	// in the sampler if NAPSAC or Progressive-NAPSAC sampling is applied.
	std::chrono::time_point<std::chrono::system_clock> start, end; // Variables for time measurement
	start = std::chrono::system_clock::now(); // The starting time of the neighborhood calculation
	neighborhood::GridNeighborhoodGraph<2> neighborhood(&points, // The data points
		{ image.cols / 16.0,
			image.rows / 16.0 },
		16); // The radius of the neighborhood sphere used for determining the neighborhood structure
	end = std::chrono::system_clock::now(); // The end time of the neighborhood calculation
	std::chrono::duration<double> elapsed_seconds = end - start; // The elapsed time in seconds