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* Copyright 2008-2009 Marius Muja (mariusm@cs.ubc.ca). All rights reserved.
* Copyright 2008-2009 David G. Lowe (lowe@cs.ubc.ca). All rights reserved.
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#ifndef OPENCV_FLANN_GROUND_TRUTH_H_
#define OPENCV_FLANN_GROUND_TRUTH_H_
#include "dist.h"
#include "matrix.h"
namespace cvflann
{
template <typename Distance>
void find_nearest(const Matrix<typename Distance::ElementType>& dataset, typename Distance::ElementType* query, int* matches, int nn,
int skip = 0, Distance distance = Distance())
{
typedef typename Distance::ResultType DistanceType;
int n = nn + skip;
std::vector<int> match(n);
std::vector<DistanceType> dists(n);
dists[0] = distance(dataset[0], query, dataset.cols);
match[0] = 0;
int dcnt = 1;
for (size_t i=1; i<dataset.rows; ++i) {
DistanceType tmp = distance(dataset[i], query, dataset.cols);
if (dcnt<n) {
match[dcnt] = (int)i;
dists[dcnt++] = tmp;
}
else if (tmp < dists[dcnt-1]) {
dists[dcnt-1] = tmp;
match[dcnt-1] = (int)i;
}
int j = dcnt-1;
// bubble up
while (j>=1 && dists[j]<dists[j-1]) {
std::swap(dists[j],dists[j-1]);
std::swap(match[j],match[j-1]);
j--;
}
}
for (int i=0; i<nn; ++i) {
matches[i] = match[i+skip];
}
}
template <typename Distance>
void compute_ground_truth(const Matrix<typename Distance::ElementType>& dataset, const Matrix<typename Distance::ElementType>& testset, Matrix<int>& matches,
int skip=0, Distance d = Distance())
{
for (size_t i=0; i<testset.rows; ++i) {
find_nearest<Distance>(dataset, testset[i], matches[i], (int)matches.cols, skip, d);
}
}
}
#endif //OPENCV_FLANN_GROUND_TRUTH_H_