Example Detect Corners - Revision history

Peter at 23:05, 2 September 2022

2022-09-02T23:05:47Z

← Older revision		Revision as of 23:05, 2 September 2022
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	* Image Features		* Image Features
	* SFM		* SFM

			Related:
			* [[Example_Feature_Selector_Limit\| Feature Selector Limit]]

	= Example Code =		= Example Code =

Peter at 20:53, 17 January 2022

2022-01-17T20:53:20Z

← Older revision		Revision as of 20:53, 17 January 2022
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	Example Code:		Example Code:
	* [https://github.com/lessthanoptimal/BoofCV/blob/v0.38/examples/src/boofcv/examples/features/ExampleCornerFeature.java ExampleCornerFeature.java]		* [https://github.com/lessthanoptimal/BoofCV/blob/v0.40/examples/src/boofcv/examples/features/ExampleCornerFeature.java ExampleCornerFeature.java]

	Concepts:		Concepts:
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	ImageGradient<GrayU8, GrayS16> sobel = FactoryDerivative.sobel(GrayU8.class, GrayS16.class);		ImageGradient<GrayU8, GrayS16> sobel = FactoryDerivative.sobel(GrayU8.class, GrayS16.class);

	BufferedImage image = UtilImageIO.~~loadImage~~(UtilIO.pathExample("calibration/mono/Sony_DSC-HX5V_Chess/frame05.jpg"));		BufferedImage image = UtilImageIO.loadImageNotNull(UtilIO.pathExample("calibration/mono/Sony_DSC-HX5V_Chess/frame05.jpg"));

	// Convert the image into a usable format and predeclare memory		// Convert the image into a usable format and predeclare memory

Peter at 17:38, 12 July 2021

2021-07-12T17:38:51Z

← Older revision		Revision as of 17:38, 12 July 2021
Line 8:		Line 8:

	Example Code:		Example Code:
	* [https://github.com/lessthanoptimal/BoofCV/blob/v0.37/examples/src/boofcv/examples/features/ExampleCornerFeature.java ExampleCornerFeature.java]		* [https://github.com/lessthanoptimal/BoofCV/blob/v0.38/examples/src/boofcv/examples/features/ExampleCornerFeature.java ExampleCornerFeature.java]

	Concepts:		Concepts:
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	*/		*/
	public class ExampleCornerFeature {		public class ExampleCornerFeature {
	public static void main(String[] args) {		public static void main( String[] args ) {
	ConfigGeneralDetector configNonMax = new ConfigGeneralDetector();		ConfigGeneralDetector configNonMax = new ConfigGeneralDetector();
	// a large radius is used to exaggerate weighted/unweighted affects. Try 1 or 2 for a typical value		// a large radius is used to exaggerate weighted/unweighted affects. Try 1 or 2 for a typical value
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	// set weighted to false and see what happens to the feature's locations. unweighted is much faster		// set weighted to false and see what happens to the feature's locations. unweighted is much faster
	GeneralFeatureDetector<GrayU8,GrayS16> detector = FactoryDetectPoint.createShiTomasi(configNonMax,configCorner, GrayS16.class);		GeneralFeatureDetector<GrayU8, GrayS16> detector = FactoryDetectPoint.createShiTomasi(configNonMax, configCorner, GrayS16.class);
	ImageGradient<GrayU8, GrayS16> sobel = FactoryDerivative.sobel(GrayU8.class,GrayS16.class);		ImageGradient<GrayU8, GrayS16> sobel = FactoryDerivative.sobel(GrayU8.class, GrayS16.class);

	BufferedImage image = UtilImageIO.loadImage(UtilIO.pathExample("calibration/mono/Sony_DSC-HX5V_Chess/frame05.jpg"));		BufferedImage image = UtilImageIO.loadImage(UtilIO.pathExample("calibration/mono/Sony_DSC-HX5V_Chess/frame05.jpg"));

	// Convert the image into a usable format and predeclare memory		// Convert the image into a usable format and predeclare memory
	GrayU8 gray = ConvertBufferedImage.convertFrom(image,(GrayU8)null);		GrayU8 gray = ConvertBufferedImage.convertFrom(image, (GrayU8)null);
	GrayS16 derivX = new GrayS16(gray.width,gray.height);		GrayS16 derivX = new GrayS16(gray.width, gray.height);
	GrayS16 derivY = new GrayS16(gray.width,gray.height);		GrayS16 derivY = new GrayS16(gray.width, gray.height);

	// The first image derivatives are needed		// The first image derivatives are needed
	sobel.process(gray, derivX,derivY);		sobel.process(gray, derivX, derivY);

	// Compute the corners		// Compute the corners
	detector.process(gray,derivX,derivY,null,null,null);		detector.process(gray, derivX, derivY, null, null, null);

	// Visualize the results		// Visualize the results
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	for (int i = 0; i < corners.size; i++) {		for (int i = 0; i < corners.size; i++) {
	Point2D_I16 c = corners.get(i);		Point2D_I16 c = corners.get(i);
	VisualizeFeatures.drawPoint(g2,c.x,c.y,4,Color.RED,true);		VisualizeFeatures.drawPoint(g2, c.x, c.y, 4, Color.RED, true);
	}		}

	ShowImages.showWindow(image,"Corners",true);		ShowImages.showWindow(image, "Corners", true);
	}		}
	}		}
	</syntaxhighlight>		</syntaxhighlight>

Peter at 19:57, 21 December 2020

2020-12-21T19:57:36Z

← Older revision		Revision as of 19:57, 21 December 2020
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	Example Code:		Example Code:
	* [https://github.com/lessthanoptimal/BoofCV/blob/v0.34/examples/src/boofcv/examples/features/ExampleCornerFeature.java ExampleCornerFeature.java]		* [https://github.com/lessthanoptimal/BoofCV/blob/v0.37/examples/src/boofcv/examples/features/ExampleCornerFeature.java ExampleCornerFeature.java]

	Concepts:		Concepts:

Peter: Created page with " file:Example_corner_points.png | Detected Shi-Tomasi corner points. Corner features and other point feature..."

2019-07-07T18:14:10Z

Created page with "<center> <gallery widths=640px heights=260px> file:Example_corner_points.png | Detected Shi-Tomasi corner points. </gallery> </center> Corner features and other point feature..."

New page

<center>
<gallery widths=640px heights=260px>
file:Example_corner_points.png | Detected Shi-Tomasi corner points.
</gallery>
</center>

Corner features and other point features (e.g. Laplacian) are commonly used in SFM and 2D geometric applications. Perhaps the most well known corner feature is Shi-Tomasi (a.k.a. Good Features) and Harris corner features.

Example Code:
* [https://github.com/lessthanoptimal/BoofCV/blob/v0.34/examples/src/boofcv/examples/features/ExampleCornerFeature.java ExampleCornerFeature.java]

Concepts:
* Image Features
* SFM

= Example Code =

<syntaxhighlight lang="java">
/**
* Example showing how corner features can be detected. These features are not scale invariant, but are
* fast to compute. In OpenCV Shi-Tomasi has the name of goodFeaturesToTrack and uses the unweighted variant.
*
* @author Peter Abeles
*/
public class ExampleCornerFeature {
public static void main(String[] args) {
ConfigGeneralDetector configNonMax = new ConfigGeneralDetector();
// a large radius is used to exaggerate weighted/unweighted affects. Try 1 or 2 for a typical value
configNonMax.radius = 10;
configNonMax.threshold = 100;
configNonMax.maxFeatures = 100;
ConfigShiTomasi configCorner = new ConfigShiTomasi();
configCorner.radius = configNonMax.radius; // in general you should use the same radius here
configCorner.weighted = true; // weighted corners will appear at the corners on a chessboard

// set weighted to false and see what happens to the feature's locations. unweighted is much faster
GeneralFeatureDetector<GrayU8,GrayS16> detector = FactoryDetectPoint.createShiTomasi(configNonMax,configCorner, GrayS16.class);
ImageGradient<GrayU8, GrayS16> sobel = FactoryDerivative.sobel(GrayU8.class,GrayS16.class);

BufferedImage image = UtilImageIO.loadImage(UtilIO.pathExample("calibration/mono/Sony_DSC-HX5V_Chess/frame05.jpg"));

// Convert the image into a usable format and predeclare memory
GrayU8 gray = ConvertBufferedImage.convertFrom(image,(GrayU8)null);
GrayS16 derivX = new GrayS16(gray.width,gray.height);
GrayS16 derivY = new GrayS16(gray.width,gray.height);

// The first image derivatives are needed
sobel.process(gray, derivX,derivY);

// Compute the corners
detector.process(gray,derivX,derivY,null,null,null);

// Visualize the results
QueueCorner corners = detector.getMaximums();
Graphics2D g2 = image.createGraphics();
for (int i = 0; i < corners.size; i++) {
Point2D_I16 c = corners.get(i);
VisualizeFeatures.drawPoint(g2,c.x,c.y,4,Color.RED,true);
}

ShowImages.showWindow(image,"Corners",true);
}
}
</syntaxhighlight>