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GeoRegression is a free Java based geometry library for scientific computing in fields such as robotics and computer vision with a focus on 2D/3D space.
/*
* Copyright (C) 2011-2015, Peter Abeles. All Rights Reserved.
*
* This file is part of Geometric Regression Library (GeoRegression).
*
* 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 georegression.transform.homography;
import georegression.struct.homography.Homography2D_F64;
import georegression.struct.point.Point2D_F64;
/**
* Applies homography transform to 2D points.
*
* @author Peter Abeles
*/
public class HomographyPointOps_F64 {
/**
* Applies a 2D homography transform to the point and stores the results in another
* variable. b = H*a, where 'a' is the input/orig point, 'b' is the output/result point, and 'H'
* is a homography from a to b.
*
* @param H Homography transform
* @param orig Original point being transformed. Not modified.
* @param result Where the results are stored. Can be the same as orig. If null a new
* instance is created. Modified.
* @return Transformed point.
*/
public static Point2D_F64 transform( Homography2D_F64 H, Point2D_F64 orig, Point2D_F64 result ) {
if( result == null ) {
result = new Point2D_F64();
}
// copy the values so that no errors happen if orig and result are the same instance
double x = orig.x;
double y = orig.y;
double z = H.a31 * x + H.a32 * y + H.a33;
result.x = (H.a11 * x + H.a12 * y + H.a13)/z;
result.y = (H.a21 * x + H.a22 * y + H.a23)/z;
return result;
}
/**
* Applies a 2D homography transform to the point and stores the results in another
* variable. b = H*a, where 'a' is the input/orig point, 'b' is the output/result point, and 'H'
* is a homography from a to b.
*
* @param H Homography transform
* @param x Original x-coordinate
* @param y Original y-coordinate
* @param result Where the results are stored. Can be the same as orig. If null a new
* instance is created. Modified.
* @return Transformed point.
*/
public static Point2D_F64 transform( Homography2D_F64 H, double x , double y , Point2D_F64 result ) {
if( result == null ) {
result = new Point2D_F64();
}
double z = H.a31 * x + H.a32 * y + H.a33;
result.x = (H.a11 * x + H.a12 * y + H.a13)/z;
result.y = (H.a21 * x + H.a22 * y + H.a23)/z;
return result;
}
}