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BoofCV is an open source Java library for real-time computer vision and robotics applications.

There is a newer version: 1.1.7

/*
 * Copyright (c) 2021, Peter Abeles. All Rights Reserved.
 *
 * This file is part of BoofCV (http://boofcv.org).
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *   http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package boofcv.alg.geo.robust;

import boofcv.struct.geo.AssociatedPair;
import georegression.struct.affine.Affine2D_F64;
import georegression.struct.point.Point2D_F64;
import georegression.transform.affine.AffinePointOps_F64;
import org.ddogleg.fitting.modelset.DistanceFromModel;

import java.util.List;

/**
 * 
 * Applies an affine transformation to the associated pair and computes the euclidean distance
 * squared between their locations. This reduces computations by avoiding the square root
 * functions, which is computationally expensive. While both this error metric and euclidean
 * distance have the same minimum, this exaggerates the magnitude of outliers.
 * The transform is applied to the "keyLoc".
 * 
 *
 * @author Peter Abeles
 */
@SuppressWarnings({"NullAway.Init"})
public class DistanceAffine2DSq implements DistanceFromModel {

	Affine2D_F64 model;
	Point2D_F64 expected = new Point2D_F64();

	@Override
	public void setModel( Affine2D_F64 model ) {
		this.model = model;
	}

	@Override
	public double distance( AssociatedPair pt ) {
		AffinePointOps_F64.transform(model, pt.p1, expected);

		return expected.distance2(pt.p2);
	}

	@Override
	public void distances( List points, double[] distance ) {
		for (int i = 0; i < points.size(); i++) {
			AssociatedPair p = points.get(i);
			AffinePointOps_F64.transform(model, p.p1, expected);

			distance[i] = expected.distance2(p.p2);
		}
	}

	@Override
	public Class getPointType() {
		return AssociatedPair.class;
	}

	@Override
	public Class getModelType() {
		return Affine2D_F64.class;
	}
}