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BoofCV is an open source Java library for real-time computer vision and robotics applications.
/*
* 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.distort.kanbra;
/**
* Common functions for computing the forward and inverse model.
*
* @author Peter Abeles
*/
public class KannalaBrandtUtils_F64 {
public static double polynomial( double[] coefs, double x ) {
double pow = x;
double result = 0;
for (int i = 0; i < coefs.length; i++) {
result += coefs[i]*pow;
pow *= x*x;
}
return result;
}
public static double polytrig( double[] coefs, double cos, double sin ) {
if (coefs.length == 0)
return 0.0;
double result = 0;
result += coefs[0]*cos;
result += coefs[1]*sin;
// sin(2*phi) = 2*cos(phi)*sin(phi)
// cos(2*phi) = 2*cos^2(phi)-1
result += coefs[2]*2.0*cos*sin;
result += coefs[3]*(2.0*cos*cos - 1.0);
return result;
}
/**
* Computes the gradient as a function of the coefficients
*/
public static void polytrigGradient( double cos, double sin, double[] gradient ) {
gradient[0] = cos;
gradient[1] = sin;
gradient[2] = 2.0*cos*sin;
gradient[3] = 2.0*cos*cos - 1.0;
}
public static double polynomialDerivative( double[] coefs, double x ) {
double pow = 1.0;
double left = 1.0;
double result = 0.0;
for (int i = 0; i < coefs.length; i++) {
result += left*coefs[i]*pow;
pow *= x*x;
left += 2;
}
return result;
}
public static double polytrigDerivative( double[] coefs, double cos, double sin ) {
if (coefs.length == 0)
return 0.0;
double result = 0;
result -= coefs[0]*sin;
result += coefs[1]*cos;
result += 2*coefs[2]*(cos*cos - sin*sin);
result -= 4*coefs[3]*cos*sin;
return result;
}
}