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// Copyright (c) 2010 libmv authors.
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to
// deal in the Software without restriction, including without limitation the
// rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
// sell copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in
// all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
// FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
// IN THE SOFTWARE.
#include "libmv/multiview/conditioning.h"
#include "libmv/multiview/projection.h"
namespace libmv {
// HZ 4.4.4 pag.109: Point conditioning (non isotropic)
void PreconditionerFromPoints(const Mat &points, Mat3 *T) {
Vec mean, variance;
MeanAndVarianceAlongRows(points, &mean, &variance);
double xfactor = sqrt(2.0 / variance(0));
double yfactor = sqrt(2.0 / variance(1));
// If variance is equal to 0.0 set scaling factor to identity.
// -> Else it will provide nan value (because division by 0).
if (variance(0) < 1e-8)
xfactor = mean(0) = 1.0;
if (variance(1) < 1e-8)
yfactor = mean(1) = 1.0;
*T << xfactor, 0, -xfactor * mean(0),
0, yfactor, -yfactor * mean(1),
0, 0, 1;
}
// HZ 4.4.4 pag.107: Point conditioning (isotropic)
void IsotropicPreconditionerFromPoints(const Mat &points, Mat3 *T) {
Vec mean, variance;
MeanAndVarianceAlongRows(points, &mean, &variance);
double var_norm = variance.norm();
double factor = sqrt(2.0 / var_norm);
// If variance is equal to 0.0 set scaling factor to identity.
// -> Else it will provide nan value (because division by 0).
if (var_norm < 1e-8) {
factor = 1.0;
mean.setOnes();
}
*T << factor, 0, -factor * mean(0),
0, factor, -factor * mean(1),
0, 0, 1;
}
void ApplyTransformationToPoints(const Mat &points,
const Mat3 &T,
Mat *transformed_points) {
int n = points.cols();
transformed_points->resize(2, n);
Mat3X p(3, n);
EuclideanToHomogeneous(points, &p);
p = T * p;
HomogeneousToEuclidean(p, transformed_points);
}
void NormalizePoints(const Mat &points,
Mat *normalized_points,
Mat3 *T) {
PreconditionerFromPoints(points, T);
ApplyTransformationToPoints(points, *T, normalized_points);
}
void NormalizeIsotropicPoints(const Mat &points,
Mat *normalized_points,
Mat3 *T) {
IsotropicPreconditionerFromPoints(points, T);
ApplyTransformationToPoints(points, *T, normalized_points);
}
// Denormalize the results. See HZ page 109.
void UnnormalizerT::Unnormalize(const Mat3 &T1, const Mat3 &T2, Mat3 *H) {
*H = T2.transpose() * (*H) * T1;
}
void UnnormalizerI::Unnormalize(const Mat3 &T1, const Mat3 &T2, Mat3 *H) {
*H = T2.inverse() * (*H) * T1;
}
} // namespace libmv
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