Example Fiducial Square Image

Demonstration how to detect square image fiducials. After the fiducial detector has been created a description of each image it detects is passed in. These images are converted into binary images and resized if needed. A large number of unique fiducials can be detected with a linear growth in computational time.

Example Code:

Concepts:

• Fiducials
• Pose estimation

Relevant Examples/Tutorials:

Videos

Example Code

```/**
* Detects square binary fiducials inside an image, writes out there pose, and visualizes a virtual flat cube
* above them in the input image.
*
* @author Peter Abeles
*/
public class ExampleFiducialImage {
public static void main( String[] args ) {
String imagePath = UtilIO.pathExample("fiducial/image/examples/");
String patternPath = UtilIO.pathExample("fiducial/image/patterns/");

//		String imageName = "image00.jpg";
String imageName = "image01.jpg";
//		String imageName = "image02.jpg";

// load the lens distortion parameters and the input image
CameraPinholeBrown param = CalibrationIO.load(new File(imagePath, "intrinsic.yaml"));
LensDistortionNarrowFOV lensDistortion = new LensDistortionBrown(param);
GrayF32 original = ConvertBufferedImage.convertFrom(input, true, ImageType.single(GrayF32.class));

// Detect the fiducial
SquareImage_to_FiducialDetector<GrayF32> detector = FactoryFiducial.squareImage(
new ConfigFiducialImage(), ConfigThreshold.local(ThresholdType.LOCAL_MEAN, 21), GrayF32.class);
//				new ConfigFiducialImage(), ConfigThreshold.fixed(100), GrayF32.class);

// give it a description of all the targets
double width = 4; // 4 cm

detector.setLensDistortion(lensDistortion, param.width, param.height);

detector.detect(original);

// print the results
Graphics2D g2 = input.createGraphics();
var targetToSensor = new Se3_F64();
var locationPixel = new Point2D_F64();
var bounds = new Polygon2D_F64();
for (int i = 0; i < detector.totalFound(); i++) {
detector.getCenter(i, locationPixel);
detector.getBounds(i, bounds);

g2.setColor(new Color(50, 50, 255));
g2.setStroke(new BasicStroke(10));
VisualizeShapes.drawPolygon(bounds, true, 1.0, g2);

if (detector.hasID())
System.out.println("Target ID = " + detector.getId(i));
if (detector.hasMessage())
System.out.println("Message   = " + detector.getMessage(i));
System.out.println("2D Image Location = " + locationPixel);

if (detector.is3D()) {
detector.getFiducialToCamera(i, targetToSensor);
System.out.println("3D Location:");
System.out.println(targetToSensor);
VisualizeFiducial.drawCube(targetToSensor, param, detector.getWidth(i), 3, g2);
VisualizeFiducial.drawLabelCenter(targetToSensor, param, "" + detector.getId(i), g2);
} else {
VisualizeFiducial.drawLabel(locationPixel, "" + detector.getId(i), g2);
}
}

ShowImages.showWindow(input, "Fiducials", true);
}
}
```