Example Detect Calibration Target

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  Red dots are detected calibration points on a chessboard target. The entire target must be visible for detection to work.

BoofCV provides fully automated calibration target detection. Once detected calibration point locations are returned with a high level of precision. While intended for camera calibration, they can also be used for other applications, such as augmented reality. In this example it is demonstrated how to detect different types of grid based targets.

Example File: ExampleDetectCalibrationPoints.java

Concepts:

• Fiducials / Markers
• Calibration

Related Examples/Tutorials:

• Tutorial Camera Calibration
• Chessboard Detector Paper

Videos:

• Circle Asymmetric Grid
• X-Corner Chessboard Detector

Example Code

/**
 * Example that demonstrates how to detect calibration targets. Calibration points are found on the
 * targets to a high level of precision. It is assumed that a single image only shows a single target
 * and that the entire target is visible. If these conditions are not meet then the target is likely
 * to not be detected.
 *
 * @author Peter Abeles
 */
public class ExampleDetectCalibrationPoints {
	public static void main( String[] args ) {
		// load the test image
//		String directory = UtilIO.pathExample("calibration/stereo/Bumblebee2_Square");
		String directory = UtilIO.pathExample("calibration/stereo/Bumblebee2_Chess");

		BufferedImage orig = UtilImageIO.loadImageNotNull(directory + "/left01.jpg");
		GrayF32 input = ConvertBufferedImage.convertFrom(orig, (GrayF32)null);

		// To select different types of detectors add or remove comments below
		DetectSingleFiducialCalibration detector;

		// For chessboard targets, tune RADIUS parameter for your images
//		detector = FactoryFiducialCalibration.squareGrid(null, new ConfigGridDimen(4, 3, 30, 30));
		detector = FactoryFiducialCalibration.chessboardX(null, new ConfigGridDimen(/*rows*/ 7, /*cols*/ 5, /*shape size*/ 30));

		// process the image and check for failure condition
		if (!detector.process(input))
			throw new RuntimeException("Target detection failed!");

		// Ordered observations of calibration points on the target
		CalibrationObservation set = detector.getDetectedPoints();

		// render and display the results
		Graphics2D g2 = orig.createGraphics();
		for (PointIndex2D_F64 p : set.points)
			VisualizeFeatures.drawPoint(g2, p.p.x, p.p.y, 3, Color.RED, true);

		ShowImages.showWindow(orig, "Calibration Points", true);
	}
}