boofcv.alg.geo.h.HomographyInducedStereoLinePt Maven / Gradle / Ivy
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/*
* 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.h;
import boofcv.alg.geo.MultiViewOps;
import boofcv.struct.geo.AssociatedPair;
import boofcv.struct.geo.PairLineNorm;
import georegression.geometry.GeometryMath_F64;
import georegression.struct.point.Point3D_F64;
import org.ejml.data.DMatrixRMaj;
import org.ejml.dense.row.CommonOps_DDRM;
import org.jetbrains.annotations.Nullable;
/**
*
* Computes the homography induced by a plane from correspondences of a line and a point. Works with both
* calibrated and uncalibrated cameras. The Fundamental/Essential matrix must be known. The found homography will be
* from view 1 to view 2. The passed in Fundamental matrix must have the following properties for each set of
* point correspondences: x2*F*x1 = 0, where x1 and x2 are views of the point in image 1 and image 2 respectively.
* For more information see [1].
*
*
*
* NOTE: Any line which is parallel to camera baseline can't be used. The lines in both cameras will have the same
* slope, causing their intersection to be a plane instead of a line. This can be a significant issue since for
* many stereo rigs it would mean no perfectly horizontal lines can be used.
*
*
*
* [1] R. Hartley, and A. Zisserman, "Multiple View Geometry in Computer Vision", 2nd Ed, Cambridge 2003
*
*
* @author Peter Abeles
*/
@SuppressWarnings({"NullAway.Init"})
public class HomographyInducedStereoLinePt {
// Fundamental matrix
private DMatrixRMaj F;
// Epipole in camera 2
private final Point3D_F64 e2 = new Point3D_F64();
// The found homography from view 1 to view 2
private final DMatrixRMaj H = new DMatrixRMaj(3, 3);
// pick a reasonable scale and sign
private final AdjustHomographyMatrix adjust = new AdjustHomographyMatrix();
// storage for intermediate results
private final DMatrixRMaj el = new DMatrixRMaj(3, 3);
private final DMatrixRMaj lf = new DMatrixRMaj(3, 3);
private final Point3D_F64 Fx = new Point3D_F64();
private final Point3D_F64 t0 = new Point3D_F64();
private final Point3D_F64 t1 = new Point3D_F64();
/**
* Specify the fundamental matrix and the camera 2 epipole.
*
* @param F Fundamental matrix.
* @param e2 Epipole for camera 2. If null it will be computed internally.
*/
public void setFundamental( DMatrixRMaj F, @Nullable Point3D_F64 e2 ) {
this.F = F;
if (e2 != null)
this.e2.setTo(e2);
else {
MultiViewOps.extractEpipoles(F, new Point3D_F64(), this.e2);
}
}
/**
* Computes the homography based on a line and point on the plane
*
* @param line Line on the plane
* @param point Point on the plane
*/
public void process( PairLineNorm line, AssociatedPair point ) {
// t0 = (F*x) cross l'
GeometryMath_F64.mult(F, point.p1, Fx);
GeometryMath_F64.cross(Fx, line.getL2(), t0);
// t1 = x' cross ((f*x) cross l')
GeometryMath_F64.cross(point.p2, t0, t1);
// t0 = x' cross e'
GeometryMath_F64.cross(point.p2, e2, t0);
double top = GeometryMath_F64.dot(t0, t1);
double bottom = t0.normSq()*(line.l1.x*point.p1.x + line.l1.y*point.p1.y + line.l1.z);
// e' * l^T
GeometryMath_F64.outerProd(e2, line.l1, el);
// cross(l')*F
GeometryMath_F64.multCrossA(line.l2, F, lf);
CommonOps_DDRM.add(lf, top/bottom, el, H);
// pick a good scale and sign for H
adjust.adjust(H, point);
}
public DMatrixRMaj getHomography() {
return H;
}
}