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opencv/modules/features2d/src/brisk.cpp

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/*********************************************************************
* Software License Agreement (BSD License)
*
* Copyright (C) 2011 The Autonomous Systems Lab (ASL), ETH Zurich,
* Stefan Leutenegger, Simon Lynen and Margarita Chli.
* Copyright (c) 2009, Willow Garage, Inc.
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* * Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* * Redistributions in binary form must reproduce the above
* copyright notice, this list of conditions and the following
* disclaimer in the documentation and/or other materials provided
* with the distribution.
* * Neither the name of the Willow Garage nor the names of its
* contributors may be used to endorse or promote products derived
* from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
* CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
* ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*********************************************************************/
/*
BRISK - Binary Robust Invariant Scalable Keypoints
Reference implementation of
[1] Stefan Leutenegger,Margarita Chli and Roland Siegwart, BRISK:
Binary Robust Invariant Scalable Keypoints, in Proceedings of
the IEEE International Conference on Computer Vision (ICCV2011).
*/
#include "precomp.hpp"
#include <fstream>
#include <stdlib.h>
#include "agast_score.hpp"
namespace cv
{
class BRISK_Impl CV_FINAL : public BRISK
{
public:
explicit BRISK_Impl(int thresh=30, int octaves=3, float patternScale=1.0f);
// custom setup
explicit BRISK_Impl(const std::vector<float> &radiusList, const std::vector<int> &numberList,
float dMax=5.85f, float dMin=8.2f, const std::vector<int> indexChange=std::vector<int>());
explicit BRISK_Impl(int thresh, int octaves, const std::vector<float> &radiusList,
const std::vector<int> &numberList, float dMax=5.85f, float dMin=8.2f,
const std::vector<int> indexChange=std::vector<int>());
virtual ~BRISK_Impl();
int descriptorSize() const CV_OVERRIDE
{
return strings_;
}
int descriptorType() const CV_OVERRIDE
{
return CV_8U;
}
int defaultNorm() const CV_OVERRIDE
{
return NORM_HAMMING;
}
virtual void setThreshold(int threshold_in) CV_OVERRIDE
{
threshold = threshold_in;
}
virtual int getThreshold() const CV_OVERRIDE
{
return threshold;
}
virtual void setOctaves(int octaves_in) CV_OVERRIDE
{
octaves = octaves_in;
}
virtual int getOctaves() const CV_OVERRIDE
{
return octaves;
}
// call this to generate the kernel:
// circle of radius r (pixels), with n points;
// short pairings with dMax, long pairings with dMin
void generateKernel(const std::vector<float> &radiusList,
const std::vector<int> &numberList, float dMax=5.85f, float dMin=8.2f,
const std::vector<int> &indexChange=std::vector<int>());
void detectAndCompute( InputArray image, InputArray mask,
CV_OUT std::vector<KeyPoint>& keypoints,
OutputArray descriptors,
bool useProvidedKeypoints ) CV_OVERRIDE;
protected:
void computeKeypointsNoOrientation(InputArray image, InputArray mask, std::vector<KeyPoint>& keypoints) const;
void computeDescriptorsAndOrOrientation(InputArray image, InputArray mask, std::vector<KeyPoint>& keypoints,
OutputArray descriptors, bool doDescriptors, bool doOrientation,
bool useProvidedKeypoints) const;
// Feature parameters
CV_PROP_RW int threshold;
CV_PROP_RW int octaves;
// some helper structures for the Brisk pattern representation
struct BriskPatternPoint{
float x; // x coordinate relative to center
float y; // x coordinate relative to center
float sigma; // Gaussian smoothing sigma
};
struct BriskShortPair{
unsigned int i; // index of the first pattern point
unsigned int j; // index of other pattern point
};
struct BriskLongPair{
unsigned int i; // index of the first pattern point
unsigned int j; // index of other pattern point
int weighted_dx; // 1024.0/dx
int weighted_dy; // 1024.0/dy
};
inline int smoothedIntensity(const cv::Mat& image,
const cv::Mat& integral,const float key_x,
const float key_y, const unsigned int scale,
const unsigned int rot, const unsigned int point) const;
// pattern properties
BriskPatternPoint* patternPoints_; //[i][rotation][scale]
unsigned int points_; // total number of collocation points
float* scaleList_; // lists the scaling per scale index [scale]
unsigned int* sizeList_; // lists the total pattern size per scale index [scale]
static const unsigned int scales_; // scales discretization
static const float scalerange_; // span of sizes 40->4 Octaves - else, this needs to be adjusted...
static const unsigned int n_rot_; // discretization of the rotation look-up
// pairs
int strings_; // number of uchars the descriptor consists of
float dMax_; // short pair maximum distance
float dMin_; // long pair maximum distance
BriskShortPair* shortPairs_; // d<_dMax
BriskLongPair* longPairs_; // d>_dMin
unsigned int noShortPairs_; // number of shortParis
unsigned int noLongPairs_; // number of longParis
// general
static const float basicSize_;
private:
BRISK_Impl(const BRISK_Impl &); // copy disabled
BRISK_Impl& operator=(const BRISK_Impl &); // assign disabled
};
// a layer in the Brisk detector pyramid
class BriskLayer
{
public:
// constructor arguments
struct CommonParams
{
static const int HALFSAMPLE = 0;
static const int TWOTHIRDSAMPLE = 1;
};
// construct a base layer
BriskLayer(const cv::Mat& img, float scale = 1.0f, float offset = 0.0f);
// derive a layer
BriskLayer(const BriskLayer& layer, int mode);
// Agast without non-max suppression
void
getAgastPoints(int threshold, std::vector<cv::KeyPoint>& keypoints);
// get scores - attention, this is in layer coordinates, not scale=1 coordinates!
inline int
getAgastScore(int x, int y, int threshold) const;
inline int
getAgastScore_5_8(int x, int y, int threshold) const;
inline int
getAgastScore(float xf, float yf, int threshold, float scale = 1.0f) const;
// accessors
inline const cv::Mat&
img() const
{
return img_;
}
inline const cv::Mat&
scores() const
{
return scores_;
}
inline float
scale() const
{
return scale_;
}
inline float
offset() const
{
return offset_;
}
// half sampling
static inline void
halfsample(const cv::Mat& srcimg, cv::Mat& dstimg);
// two third sampling
static inline void
twothirdsample(const cv::Mat& srcimg, cv::Mat& dstimg);
private:
// access gray values (smoothed/interpolated)
inline int
value(const cv::Mat& mat, float xf, float yf, float scale) const;
// the image
cv::Mat img_;
// its Agast scores
cv::Mat_<uchar> scores_;
// coordinate transformation
float scale_;
float offset_;
// agast
cv::Ptr<cv::AgastFeatureDetector> oast_9_16_;
int pixel_5_8_[25];
int pixel_9_16_[25];
};
class BriskScaleSpace
{
public:
// construct telling the octaves number:
BriskScaleSpace(int _octaves = 3);
~BriskScaleSpace();
// construct the image pyramids
void
constructPyramid(const cv::Mat& image);
// get Keypoints
void
getKeypoints(const int _threshold, std::vector<cv::KeyPoint>& keypoints);
protected:
// nonmax suppression:
inline bool
isMax2D(const int layer, const int x_layer, const int y_layer);
// 1D (scale axis) refinement:
inline float
refine1D(const float s_05, const float s0, const float s05, float& max) const; // around octave
inline float
refine1D_1(const float s_05, const float s0, const float s05, float& max) const; // around intra
inline float
refine1D_2(const float s_05, const float s0, const float s05, float& max) const; // around octave 0 only
// 2D maximum refinement:
inline float
subpixel2D(const int s_0_0, const int s_0_1, const int s_0_2, const int s_1_0, const int s_1_1, const int s_1_2,
const int s_2_0, const int s_2_1, const int s_2_2, float& delta_x, float& delta_y) const;
// 3D maximum refinement centered around (x_layer,y_layer)
inline float
refine3D(const int layer, const int x_layer, const int y_layer, float& x, float& y, float& scale, bool& ismax) const;
// interpolated score access with recalculation when needed:
inline int
getScoreAbove(const int layer, const int x_layer, const int y_layer) const;
inline int
getScoreBelow(const int layer, const int x_layer, const int y_layer) const;
// return the maximum of score patches above or below
inline float
getScoreMaxAbove(const int layer, const int x_layer, const int y_layer, const int threshold, bool& ismax,
float& dx, float& dy) const;
inline float
getScoreMaxBelow(const int layer, const int x_layer, const int y_layer, const int threshold, bool& ismax,
float& dx, float& dy) const;
// the image pyramids:
int layers_;
std::vector<BriskLayer> pyramid_;
// some constant parameters:
static const float safetyFactor_;
static const float basicSize_;
};
const float BRISK_Impl::basicSize_ = 12.0f;
const unsigned int BRISK_Impl::scales_ = 64;
const float BRISK_Impl::scalerange_ = 30.f; // 40->4 Octaves - else, this needs to be adjusted...
const unsigned int BRISK_Impl::n_rot_ = 1024; // discretization of the rotation look-up
const float BriskScaleSpace::safetyFactor_ = 1.0f;
const float BriskScaleSpace::basicSize_ = 12.0f;
// constructors
BRISK_Impl::BRISK_Impl(int thresh, int octaves_in, float patternScale)
{
threshold = thresh;
octaves = octaves_in;
std::vector<float> rList;
std::vector<int> nList;
// this is the standard pattern found to be suitable also
rList.resize(5);
nList.resize(5);
const double f = 0.85 * patternScale;
rList[0] = (float)(f * 0.);
rList[1] = (float)(f * 2.9);
rList[2] = (float)(f * 4.9);
rList[3] = (float)(f * 7.4);
rList[4] = (float)(f * 10.8);
nList[0] = 1;
nList[1] = 10;
nList[2] = 14;
nList[3] = 15;
nList[4] = 20;
generateKernel(rList, nList, (float)(5.85 * patternScale), (float)(8.2 * patternScale));
}
BRISK_Impl::BRISK_Impl(const std::vector<float> &radiusList,
const std::vector<int> &numberList,
float dMax, float dMin,
const std::vector<int> indexChange)
{
generateKernel(radiusList, numberList, dMax, dMin, indexChange);
threshold = 20;
octaves = 3;
}
BRISK_Impl::BRISK_Impl(int thresh,
int octaves_in,
const std::vector<float> &radiusList,
const std::vector<int> &numberList,
float dMax, float dMin,
const std::vector<int> indexChange)
{
generateKernel(radiusList, numberList, dMax, dMin, indexChange);
threshold = thresh;
octaves = octaves_in;
}
void
BRISK_Impl::generateKernel(const std::vector<float> &radiusList,
const std::vector<int> &numberList,
float dMax, float dMin,
const std::vector<int>& _indexChange)
{
std::vector<int> indexChange = _indexChange;
dMax_ = dMax;
dMin_ = dMin;
// get the total number of points
const int rings = (int)radiusList.size();
CV_Assert(radiusList.size() != 0 && radiusList.size() == numberList.size());
points_ = 0; // remember the total number of points
for (int ring = 0; ring < rings; ring++)
{
points_ += numberList[ring];
}
// set up the patterns
patternPoints_ = new BriskPatternPoint[points_ * scales_ * n_rot_];
BriskPatternPoint* patternIterator = patternPoints_;
// define the scale discretization:
static const float lb_scale = (float)(std::log(scalerange_) / std::log(2.0));
static const float lb_scale_step = lb_scale / (scales_);
scaleList_ = new float[scales_];
sizeList_ = new unsigned int[scales_];
const float sigma_scale = 1.3f;
for (unsigned int scale = 0; scale < scales_; ++scale)
{
scaleList_[scale] = (float)std::pow((double) 2.0, (double) (scale * lb_scale_step));
sizeList_[scale] = 0;
// generate the pattern points look-up
double alpha, theta;
for (size_t rot = 0; rot < n_rot_; ++rot)
{
theta = double(rot) * 2 * CV_PI / double(n_rot_); // this is the rotation of the feature
for (int ring = 0; ring < rings; ++ring)
{
for (int num = 0; num < numberList[ring]; ++num)
{
// the actual coordinates on the circle
alpha = (double(num)) * 2 * CV_PI / double(numberList[ring]);
patternIterator->x = (float)(scaleList_[scale] * radiusList[ring] * cos(alpha + theta)); // feature rotation plus angle of the point
patternIterator->y = (float)(scaleList_[scale] * radiusList[ring] * sin(alpha + theta));
// and the gaussian kernel sigma
if (ring == 0)
{
patternIterator->sigma = sigma_scale * scaleList_[scale] * 0.5f;
}
else
{
patternIterator->sigma = (float)(sigma_scale * scaleList_[scale] * (double(radiusList[ring]))
* sin(CV_PI / numberList[ring]));
}
// adapt the sizeList if necessary
const unsigned int size = cvCeil(((scaleList_[scale] * radiusList[ring]) + patternIterator->sigma)) + 1;
if (sizeList_[scale] < size)
{
sizeList_[scale] = size;
}
// increment the iterator
++patternIterator;
}
}
}
}
// now also generate pairings
shortPairs_ = new BriskShortPair[points_ * (points_ - 1) / 2];
longPairs_ = new BriskLongPair[points_ * (points_ - 1) / 2];
noShortPairs_ = 0;
noLongPairs_ = 0;
// fill indexChange with 0..n if empty
unsigned int indSize = (unsigned int)indexChange.size();
if (indSize == 0)
{
indexChange.resize(points_ * (points_ - 1) / 2);
indSize = (unsigned int)indexChange.size();
for (unsigned int i = 0; i < indSize; i++)
indexChange[i] = i;
}
const float dMin_sq = dMin_ * dMin_;
const float dMax_sq = dMax_ * dMax_;
for (unsigned int i = 1; i < points_; i++)
{
for (unsigned int j = 0; j < i; j++)
{ //(find all the pairs)
// point pair distance:
const float dx = patternPoints_[j].x - patternPoints_[i].x;
const float dy = patternPoints_[j].y - patternPoints_[i].y;
const float norm_sq = (dx * dx + dy * dy);
if (norm_sq > dMin_sq)
{
// save to long pairs
BriskLongPair& longPair = longPairs_[noLongPairs_];
longPair.weighted_dx = int((dx / (norm_sq)) * 2048.0 + 0.5);
longPair.weighted_dy = int((dy / (norm_sq)) * 2048.0 + 0.5);
longPair.i = i;
longPair.j = j;
++noLongPairs_;
}
else if (norm_sq < dMax_sq)
{
// save to short pairs
CV_Assert(noShortPairs_ < indSize);
// make sure the user passes something sensible
BriskShortPair& shortPair = shortPairs_[indexChange[noShortPairs_]];
shortPair.j = j;
shortPair.i = i;
++noShortPairs_;
}
}
}
// no bits:
strings_ = (int) ceil((float(noShortPairs_)) / 128.0) * 4 * 4;
}
// simple alternative:
inline int
BRISK_Impl::smoothedIntensity(const cv::Mat& image, const cv::Mat& integral, const float key_x,
const float key_y, const unsigned int scale, const unsigned int rot,
const unsigned int point) const
{
// get the float position
const BriskPatternPoint& briskPoint = patternPoints_[scale * n_rot_ * points_ + rot * points_ + point];
const float xf = briskPoint.x + key_x;
const float yf = briskPoint.y + key_y;
const int x = int(xf);
const int y = int(yf);
const int& imagecols = image.cols;
// get the sigma:
const float sigma_half = briskPoint.sigma;
const float area = 4.0f * sigma_half * sigma_half;
// calculate output:
int ret_val;
if (sigma_half < 0.5)
{
//interpolation multipliers:
const int r_x = (int)((xf - x) * 1024);
const int r_y = (int)((yf - y) * 1024);
const int r_x_1 = (1024 - r_x);
const int r_y_1 = (1024 - r_y);
const uchar* ptr = &image.at<uchar>(y, x);
size_t step = image.step;
// just interpolate:
ret_val = r_x_1 * r_y_1 * ptr[0] + r_x * r_y_1 * ptr[1] +
r_x * r_y * ptr[step] + r_x_1 * r_y * ptr[step+1];
return (ret_val + 512) / 1024;
}
// this is the standard case (simple, not speed optimized yet):
// scaling:
const int scaling = (int)(4194304.0 / area);
const int scaling2 = int(float(scaling) * area / 1024.0);
CV_Assert(scaling2 != 0);
// the integral image is larger:
const int integralcols = imagecols + 1;
// calculate borders
const float x_1 = xf - sigma_half;
const float x1 = xf + sigma_half;
const float y_1 = yf - sigma_half;
const float y1 = yf + sigma_half;
const int x_left = int(x_1 + 0.5);
const int y_top = int(y_1 + 0.5);
const int x_right = int(x1 + 0.5);
const int y_bottom = int(y1 + 0.5);
// overlap area - multiplication factors:
const float r_x_1 = float(x_left) - x_1 + 0.5f;
const float r_y_1 = float(y_top) - y_1 + 0.5f;
const float r_x1 = x1 - float(x_right) + 0.5f;
const float r_y1 = y1 - float(y_bottom) + 0.5f;
const int dx = x_right - x_left - 1;
const int dy = y_bottom - y_top - 1;
const int A = (int)((r_x_1 * r_y_1) * scaling);
const int B = (int)((r_x1 * r_y_1) * scaling);
const int C = (int)((r_x1 * r_y1) * scaling);
const int D = (int)((r_x_1 * r_y1) * scaling);
const int r_x_1_i = (int)(r_x_1 * scaling);
const int r_y_1_i = (int)(r_y_1 * scaling);
const int r_x1_i = (int)(r_x1 * scaling);
const int r_y1_i = (int)(r_y1 * scaling);
if (dx + dy > 2)
{
// now the calculation:
const uchar* ptr = image.ptr() + x_left + imagecols * y_top;
// first the corners:
ret_val = A * int(*ptr);
ptr += dx + 1;
ret_val += B * int(*ptr);
ptr += dy * imagecols + 1;
ret_val += C * int(*ptr);
ptr -= dx + 1;
ret_val += D * int(*ptr);
// next the edges:
const int* ptr_integral = integral.ptr<int>() + x_left + integralcols * y_top + 1;
// find a simple path through the different surface corners
const int tmp1 = (*ptr_integral);
ptr_integral += dx;
const int tmp2 = (*ptr_integral);
ptr_integral += integralcols;
const int tmp3 = (*ptr_integral);
ptr_integral++;
const int tmp4 = (*ptr_integral);
ptr_integral += dy * integralcols;
const int tmp5 = (*ptr_integral);
ptr_integral--;
const int tmp6 = (*ptr_integral);
ptr_integral += integralcols;
const int tmp7 = (*ptr_integral);
ptr_integral -= dx;
const int tmp8 = (*ptr_integral);
ptr_integral -= integralcols;
const int tmp9 = (*ptr_integral);
ptr_integral--;
const int tmp10 = (*ptr_integral);
ptr_integral -= dy * integralcols;
const int tmp11 = (*ptr_integral);
ptr_integral++;
const int tmp12 = (*ptr_integral);
// assign the weighted surface integrals:
const int upper = (tmp3 - tmp2 + tmp1 - tmp12) * r_y_1_i;
const int middle = (tmp6 - tmp3 + tmp12 - tmp9) * scaling;
const int left = (tmp9 - tmp12 + tmp11 - tmp10) * r_x_1_i;
const int right = (tmp5 - tmp4 + tmp3 - tmp6) * r_x1_i;
const int bottom = (tmp7 - tmp6 + tmp9 - tmp8) * r_y1_i;
return (ret_val + upper + middle + left + right + bottom + scaling2 / 2) / scaling2;
}
// now the calculation:
const uchar* ptr = image.ptr() + x_left + imagecols * y_top;
// first row:
ret_val = A * int(*ptr);
ptr++;
const uchar* end1 = ptr + dx;
for (; ptr < end1; ptr++)
{
ret_val += r_y_1_i * int(*ptr);
}
ret_val += B * int(*ptr);
// middle ones:
ptr += imagecols - dx - 1;
const uchar* end_j = ptr + dy * imagecols;
for (; ptr < end_j; ptr += imagecols - dx - 1)
{
ret_val += r_x_1_i * int(*ptr);
ptr++;
const uchar* end2 = ptr + dx;
for (; ptr < end2; ptr++)
{
ret_val += int(*ptr) * scaling;
}
ret_val += r_x1_i * int(*ptr);
}
// last row:
ret_val += D * int(*ptr);
ptr++;
const uchar* end3 = ptr + dx;
for (; ptr < end3; ptr++)
{
ret_val += r_y1_i * int(*ptr);
}
ret_val += C * int(*ptr);
return (ret_val + scaling2 / 2) / scaling2;
}
inline bool
RoiPredicate(const float minX, const float minY, const float maxX, const float maxY, const KeyPoint& keyPt)
{
const Point2f& pt = keyPt.pt;
return (pt.x < minX) || (pt.x >= maxX) || (pt.y < minY) || (pt.y >= maxY);
}
// computes the descriptor
void
BRISK_Impl::detectAndCompute( InputArray _image, InputArray _mask, std::vector<KeyPoint>& keypoints,
OutputArray _descriptors, bool useProvidedKeypoints)
{
bool doOrientation=true;
// If the user specified cv::noArray(), this will yield false. Otherwise it will return true.
bool doDescriptors = _descriptors.needed();
computeDescriptorsAndOrOrientation(_image, _mask, keypoints, _descriptors, doDescriptors, doOrientation,
useProvidedKeypoints);
}
void
BRISK_Impl::computeDescriptorsAndOrOrientation(InputArray _image, InputArray _mask, std::vector<KeyPoint>& keypoints,
OutputArray _descriptors, bool doDescriptors, bool doOrientation,
bool useProvidedKeypoints) const
{
Mat image = _image.getMat(), mask = _mask.getMat();
if( image.type() != CV_8UC1 )
cvtColor(image, image, COLOR_BGR2GRAY);
if (!useProvidedKeypoints)
{
doOrientation = true;
computeKeypointsNoOrientation(_image, _mask, keypoints);
}
//Remove keypoints very close to the border
size_t ksize = keypoints.size();
std::vector<int> kscales; // remember the scale per keypoint
kscales.resize(ksize);
static const float log2 = 0.693147180559945f;
static const float lb_scalerange = (float)(std::log(scalerange_) / (log2));
std::vector<cv::KeyPoint>::iterator beginning = keypoints.begin();
std::vector<int>::iterator beginningkscales = kscales.begin();
static const float basicSize06 = basicSize_ * 0.6f;
for (size_t k = 0; k < ksize; k++)
{
unsigned int scale;
scale = std::max((int) (scales_ / lb_scalerange * (std::log(keypoints[k].size / (basicSize06)) / log2) + 0.5), 0);
// saturate
if (scale >= scales_)
scale = scales_ - 1;
kscales[k] = scale;
const int border = sizeList_[scale];
const int border_x = image.cols - border;
const int border_y = image.rows - border;
if (RoiPredicate((float)border, (float)border, (float)border_x, (float)border_y, keypoints[k]))
{
keypoints.erase(beginning + k);
kscales.erase(beginningkscales + k);
if (k == 0)
{
beginning = keypoints.begin();
beginningkscales = kscales.begin();
}
ksize--;
k--;
}
}
// first, calculate the integral image over the whole image:
// current integral image
cv::Mat _integral; // the integral image
cv::integral(image, _integral);
int* _values = new int[points_]; // for temporary use
// resize the descriptors:
cv::Mat descriptors;
if (doDescriptors)
{
_descriptors.create((int)ksize, strings_, CV_8U);
descriptors = _descriptors.getMat();
descriptors.setTo(0);
}
// now do the extraction for all keypoints:
// temporary variables containing gray values at sample points:
int t1;
int t2;
// the feature orientation
const uchar* ptr = descriptors.ptr();
for (size_t k = 0; k < ksize; k++)
{
cv::KeyPoint& kp = keypoints[k];
const int& scale = kscales[k];
const float& x = kp.pt.x;
const float& y = kp.pt.y;
if (doOrientation)
{
// get the gray values in the unrotated pattern
for (unsigned int i = 0; i < points_; i++)
{
_values[i] = smoothedIntensity(image, _integral, x, y, scale, 0, i);
}
int direction0 = 0;
int direction1 = 0;
// now iterate through the long pairings
const BriskLongPair* max = longPairs_ + noLongPairs_;
for (BriskLongPair* iter = longPairs_; iter < max; ++iter)
{
CV_Assert(iter->i < points_ && iter->j < points_);
t1 = *(_values + iter->i);
t2 = *(_values + iter->j);
const int delta_t = (t1 - t2);
// update the direction:
const int tmp0 = delta_t * (iter->weighted_dx) / 1024;
const int tmp1 = delta_t * (iter->weighted_dy) / 1024;
direction0 += tmp0;
direction1 += tmp1;
}
kp.angle = (float)(atan2((float) direction1, (float) direction0) / CV_PI * 180.0);
if (!doDescriptors)
{
if (kp.angle < 0)
kp.angle += 360.f;
}
}
if (!doDescriptors)
continue;
int theta;
if (kp.angle==-1)
{
// don't compute the gradient direction, just assign a rotation of 0
theta = 0;
}
else
{
theta = (int) (n_rot_ * (kp.angle / (360.0)) + 0.5);
if (theta < 0)
theta += n_rot_;
if (theta >= int(n_rot_))
theta -= n_rot_;
}
if (kp.angle < 0)
kp.angle += 360.f;
// now also extract the stuff for the actual direction:
// let us compute the smoothed values
int shifter = 0;
//unsigned int mean=0;
// get the gray values in the rotated pattern
for (unsigned int i = 0; i < points_; i++)
{
_values[i] = smoothedIntensity(image, _integral, x, y, scale, theta, i);
}
// now iterate through all the pairings
unsigned int* ptr2 = (unsigned int*) ptr;
const BriskShortPair* max = shortPairs_ + noShortPairs_;
for (BriskShortPair* iter = shortPairs_; iter < max; ++iter)
{
CV_Assert(iter->i < points_ && iter->j < points_);
t1 = *(_values + iter->i);
t2 = *(_values + iter->j);
if (t1 > t2)
{
*ptr2 |= ((1) << shifter);
} // else already initialized with zero
// take care of the iterators:
++shifter;
if (shifter == 32)
{
shifter = 0;
++ptr2;
}
}
ptr += strings_;
}
// clean-up
delete[] _values;
}
BRISK_Impl::~BRISK_Impl()
{
delete[] patternPoints_;
delete[] shortPairs_;
delete[] longPairs_;
delete[] scaleList_;
delete[] sizeList_;
}
void
BRISK_Impl::computeKeypointsNoOrientation(InputArray _image, InputArray _mask, std::vector<KeyPoint>& keypoints) const
{
Mat image = _image.getMat(), mask = _mask.getMat();
if( image.type() != CV_8UC1 )
cvtColor(_image, image, COLOR_BGR2GRAY);
BriskScaleSpace briskScaleSpace(octaves);
briskScaleSpace.constructPyramid(image);
briskScaleSpace.getKeypoints(threshold, keypoints);
// remove invalid points
KeyPointsFilter::runByPixelsMask(keypoints, mask);
}
// construct telling the octaves number:
BriskScaleSpace::BriskScaleSpace(int _octaves)
{
if (_octaves == 0)
layers_ = 1;
else
layers_ = 2 * _octaves;
}
BriskScaleSpace::~BriskScaleSpace()
{
}
// construct the image pyramids
void
BriskScaleSpace::constructPyramid(const cv::Mat& image)
{
// set correct size:
pyramid_.clear();
// fill the pyramid:
pyramid_.push_back(BriskLayer(image.clone()));
if (layers_ > 1)
{
pyramid_.push_back(BriskLayer(pyramid_.back(), BriskLayer::CommonParams::TWOTHIRDSAMPLE));
}
const int octaves2 = layers_;
for (uchar i = 2; i < octaves2; i += 2)
{
pyramid_.push_back(BriskLayer(pyramid_[i - 2], BriskLayer::CommonParams::HALFSAMPLE));
pyramid_.push_back(BriskLayer(pyramid_[i - 1], BriskLayer::CommonParams::HALFSAMPLE));
}
}
void
BriskScaleSpace::getKeypoints(const int threshold_, std::vector<cv::KeyPoint>& keypoints)
{
// make sure keypoints is empty
keypoints.resize(0);
keypoints.reserve(2000);
// assign thresholds
int safeThreshold_ = (int)(threshold_ * safetyFactor_);
std::vector<std::vector<cv::KeyPoint> > agastPoints;
agastPoints.resize(layers_);
// go through the octaves and intra layers and calculate agast corner scores:
for (int i = 0; i < layers_; i++)
{
// call OAST16_9 without nms
BriskLayer& l = pyramid_[i];
l.getAgastPoints(safeThreshold_, agastPoints[i]);
}
if (layers_ == 1)
{
// just do a simple 2d subpixel refinement...
const size_t num = agastPoints[0].size();
for (size_t n = 0; n < num; n++)
{
const cv::Point2f& point = agastPoints.at(0)[n].pt;
// first check if it is a maximum:
if (!isMax2D(0, (int)point.x, (int)point.y))
continue;
// let's do the subpixel and float scale refinement:
BriskLayer& l = pyramid_[0];
int s_0_0 = l.getAgastScore(point.x - 1, point.y - 1, 1);
int s_1_0 = l.getAgastScore(point.x, point.y - 1, 1);
int s_2_0 = l.getAgastScore(point.x + 1, point.y - 1, 1);
int s_2_1 = l.getAgastScore(point.x + 1, point.y, 1);
int s_1_1 = l.getAgastScore(point.x, point.y, 1);
int s_0_1 = l.getAgastScore(point.x - 1, point.y, 1);
int s_0_2 = l.getAgastScore(point.x - 1, point.y + 1, 1);
int s_1_2 = l.getAgastScore(point.x, point.y + 1, 1);
int s_2_2 = l.getAgastScore(point.x + 1, point.y + 1, 1);
float delta_x, delta_y;
float max = subpixel2D(s_0_0, s_0_1, s_0_2, s_1_0, s_1_1, s_1_2, s_2_0, s_2_1, s_2_2, delta_x, delta_y);
// store:
keypoints.push_back(cv::KeyPoint(float(point.x) + delta_x, float(point.y) + delta_y, basicSize_, -1, max, 0));
}
return;
}
float x, y, scale, score;
for (int i = 0; i < layers_; i++)
{
BriskLayer& l = pyramid_[i];
const size_t num = agastPoints[i].size();
if (i == layers_ - 1)
{
for (size_t n = 0; n < num; n++)
{
const cv::Point2f& point = agastPoints.at(i)[n].pt;
// consider only 2D maxima...
if (!isMax2D(i, (int)point.x, (int)point.y))
continue;
bool ismax;
float dx, dy;
getScoreMaxBelow(i, (int)point.x, (int)point.y, l.getAgastScore(point.x, point.y, safeThreshold_), ismax, dx, dy);
if (!ismax)
continue;
// get the patch on this layer:
int s_0_0 = l.getAgastScore(point.x - 1, point.y - 1, 1);
int s_1_0 = l.getAgastScore(point.x, point.y - 1, 1);
int s_2_0 = l.getAgastScore(point.x + 1, point.y - 1, 1);
int s_2_1 = l.getAgastScore(point.x + 1, point.y, 1);
int s_1_1 = l.getAgastScore(point.x, point.y, 1);
int s_0_1 = l.getAgastScore(point.x - 1, point.y, 1);
int s_0_2 = l.getAgastScore(point.x - 1, point.y + 1, 1);
int s_1_2 = l.getAgastScore(point.x, point.y + 1, 1);
int s_2_2 = l.getAgastScore(point.x + 1, point.y + 1, 1);
float delta_x, delta_y;
float max = subpixel2D(s_0_0, s_0_1, s_0_2, s_1_0, s_1_1, s_1_2, s_2_0, s_2_1, s_2_2, delta_x, delta_y);
// store:
keypoints.push_back(
cv::KeyPoint((float(point.x) + delta_x) * l.scale() + l.offset(),
(float(point.y) + delta_y) * l.scale() + l.offset(), basicSize_ * l.scale(), -1, max, i));
}
}
else
{
// not the last layer:
for (size_t n = 0; n < num; n++)
{
const cv::Point2f& point = agastPoints.at(i)[n].pt;
// first check if it is a maximum:
if (!isMax2D(i, (int)point.x, (int)point.y))
continue;
// let's do the subpixel and float scale refinement:
bool ismax=false;
score = refine3D(i, (int)point.x, (int)point.y, x, y, scale, ismax);
if (!ismax)
{
continue;
}
// finally store the detected keypoint:
if (score > float(threshold_))
{
keypoints.push_back(cv::KeyPoint(x, y, basicSize_ * scale, -1, score, i));
}
}
}
}
}
// interpolated score access with recalculation when needed:
inline int
BriskScaleSpace::getScoreAbove(const int layer, const int x_layer, const int y_layer) const
{
CV_Assert(layer < layers_-1);
const BriskLayer& l = pyramid_[layer + 1];
if (layer % 2 == 0)
{ // octave
const int sixths_x = 4 * x_layer - 1;
const int x_above = sixths_x / 6;
const int sixths_y = 4 * y_layer - 1;
const int y_above = sixths_y / 6;
const int r_x = (sixths_x % 6);
const int r_x_1 = 6 - r_x;
const int r_y = (sixths_y % 6);
const int r_y_1 = 6 - r_y;
uchar score = 0xFF
& ((r_x_1 * r_y_1 * l.getAgastScore(x_above, y_above, 1) + r_x * r_y_1
* l.getAgastScore(x_above + 1, y_above, 1)
+ r_x_1 * r_y * l.getAgastScore(x_above, y_above + 1, 1)
+ r_x * r_y * l.getAgastScore(x_above + 1, y_above + 1, 1) + 18)
/ 36);
return score;
}
else
{ // intra
const int eighths_x = 6 * x_layer - 1;
const int x_above = eighths_x / 8;
const int eighths_y = 6 * y_layer - 1;
const int y_above = eighths_y / 8;
const int r_x = (eighths_x % 8);
const int r_x_1 = 8 - r_x;
const int r_y = (eighths_y % 8);
const int r_y_1 = 8 - r_y;
uchar score = 0xFF
& ((r_x_1 * r_y_1 * l.getAgastScore(x_above, y_above, 1) + r_x * r_y_1
* l.getAgastScore(x_above + 1, y_above, 1)
+ r_x_1 * r_y * l.getAgastScore(x_above, y_above + 1, 1)
+ r_x * r_y * l.getAgastScore(x_above + 1, y_above + 1, 1) + 32)
/ 64);
return score;
}
}
inline int
BriskScaleSpace::getScoreBelow(const int layer, const int x_layer, const int y_layer) const
{
CV_Assert(layer);
const BriskLayer& l = pyramid_[layer - 1];
int sixth_x;
int quarter_x;
float xf;
int sixth_y;
int quarter_y;
float yf;
// scaling:
float offs;
float area;
int scaling;
int scaling2;
if (layer % 2 == 0)
{ // octave
sixth_x = 8 * x_layer + 1;
xf = float(sixth_x) / 6.0f;
sixth_y = 8 * y_layer + 1;
yf = float(sixth_y) / 6.0f;
// scaling:
offs = 2.0f / 3.0f;
area = 4.0f * offs * offs;
scaling = (int)(4194304.0 / area);
scaling2 = (int)(float(scaling) * area);
}
else
{
quarter_x = 6 * x_layer + 1;
xf = float(quarter_x) / 4.0f;
quarter_y = 6 * y_layer + 1;
yf = float(quarter_y) / 4.0f;
// scaling:
offs = 3.0f / 4.0f;
area = 4.0f * offs * offs;
scaling = (int)(4194304.0 / area);
scaling2 = (int)(float(scaling) * area);
}
// calculate borders
const float x_1 = xf - offs;
const float x1 = xf + offs;
const float y_1 = yf - offs;
const float y1 = yf + offs;
const int x_left = int(x_1 + 0.5);
const int y_top = int(y_1 + 0.5);
const int x_right = int(x1 + 0.5);
const int y_bottom = int(y1 + 0.5);
// overlap area - multiplication factors:
const float r_x_1 = float(x_left) - x_1 + 0.5f;
const float r_y_1 = float(y_top) - y_1 + 0.5f;
const float r_x1 = x1 - float(x_right) + 0.5f;
const float r_y1 = y1 - float(y_bottom) + 0.5f;
const int dx = x_right - x_left - 1;
const int dy = y_bottom - y_top - 1;
const int A = (int)((r_x_1 * r_y_1) * scaling);
const int B = (int)((r_x1 * r_y_1) * scaling);
const int C = (int)((r_x1 * r_y1) * scaling);
const int D = (int)((r_x_1 * r_y1) * scaling);
const int r_x_1_i = (int)(r_x_1 * scaling);
const int r_y_1_i = (int)(r_y_1 * scaling);
const int r_x1_i = (int)(r_x1 * scaling);
const int r_y1_i = (int)(r_y1 * scaling);
// first row:
int ret_val = A * int(l.getAgastScore(x_left, y_top, 1));
for (int X = 1; X <= dx; X++)
{
ret_val += r_y_1_i * int(l.getAgastScore(x_left + X, y_top, 1));
}
ret_val += B * int(l.getAgastScore(x_left + dx + 1, y_top, 1));
// middle ones:
for (int Y = 1; Y <= dy; Y++)
{
ret_val += r_x_1_i * int(l.getAgastScore(x_left, y_top + Y, 1));
for (int X = 1; X <= dx; X++)
{
ret_val += int(l.getAgastScore(x_left + X, y_top + Y, 1)) * scaling;
}
ret_val += r_x1_i * int(l.getAgastScore(x_left + dx + 1, y_top + Y, 1));
}
// last row:
ret_val += D * int(l.getAgastScore(x_left, y_top + dy + 1, 1));
for (int X = 1; X <= dx; X++)
{
ret_val += r_y1_i * int(l.getAgastScore(x_left + X, y_top + dy + 1, 1));
}
ret_val += C * int(l.getAgastScore(x_left + dx + 1, y_top + dy + 1, 1));
return ((ret_val + scaling2 / 2) / scaling2);
}
inline bool
BriskScaleSpace::isMax2D(const int layer, const int x_layer, const int y_layer)
{
const cv::Mat& scores = pyramid_[layer].scores();
const int scorescols = scores.cols;
const uchar* data = scores.ptr() + y_layer * scorescols + x_layer;
// decision tree:
const uchar center = (*data);
data--;
const uchar s_10 = *data;
if (center < s_10)
return false;
data += 2;
const uchar s10 = *data;
if (center < s10)
return false;
data -= (scorescols + 1);
const uchar s0_1 = *data;
if (center < s0_1)
return false;
data += 2 * scorescols;
const uchar s01 = *data;
if (center < s01)
return false;
data--;
const uchar s_11 = *data;
if (center < s_11)
return false;
data += 2;
const uchar s11 = *data;
if (center < s11)
return false;
data -= 2 * scorescols;
const uchar s1_1 = *data;
if (center < s1_1)
return false;
data -= 2;
const uchar s_1_1 = *data;
if (center < s_1_1)
return false;
// reject neighbor maxima
std::vector<int> delta;
// put together a list of 2d-offsets to where the maximum is also reached
if (center == s_1_1)
{
delta.push_back(-1);
delta.push_back(-1);
}
if (center == s0_1)
{
delta.push_back(0);
delta.push_back(-1);
}
if (center == s1_1)
{
delta.push_back(1);
delta.push_back(-1);
}
if (center == s_10)
{
delta.push_back(-1);
delta.push_back(0);
}
if (center == s10)
{
delta.push_back(1);
delta.push_back(0);
}
if (center == s_11)
{
delta.push_back(-1);
delta.push_back(1);
}
if (center == s01)
{
delta.push_back(0);
delta.push_back(1);
}
if (center == s11)
{
delta.push_back(1);
delta.push_back(1);
}
const unsigned int deltasize = (unsigned int)delta.size();
if (deltasize != 0)
{
// in this case, we have to analyze the situation more carefully:
// the values are gaussian blurred and then we really decide
int smoothedcenter = 4 * center + 2 * (s_10 + s10 + s0_1 + s01) + s_1_1 + s1_1 + s_11 + s11;
for (unsigned int i = 0; i < deltasize; i += 2)
{
data = scores.ptr() + (y_layer - 1 + delta[i + 1]) * scorescols + x_layer + delta[i] - 1;
int othercenter = *data;
data++;
othercenter += 2 * (*data);
data++;
othercenter += *data;
data += scorescols;
othercenter += 2 * (*data);
data--;
othercenter += 4 * (*data);
data--;
othercenter += 2 * (*data);
data += scorescols;
othercenter += *data;
data++;
othercenter += 2 * (*data);
data++;
othercenter += *data;
if (othercenter > smoothedcenter)
return false;
}
}
return true;
}
// 3D maximum refinement centered around (x_layer,y_layer)
inline float
BriskScaleSpace::refine3D(const int layer, const int x_layer, const int y_layer, float& x, float& y, float& scale,
bool& ismax) const
{
ismax = true;
const BriskLayer& thisLayer = pyramid_[layer];
const int center = thisLayer.getAgastScore(x_layer, y_layer, 1);
// check and get above maximum:
float delta_x_above = 0, delta_y_above = 0;
float max_above = getScoreMaxAbove(layer, x_layer, y_layer, center, ismax, delta_x_above, delta_y_above);
if (!ismax)
return 0.0f;
float max; // to be returned
if (layer % 2 == 0)
{ // on octave
// treat the patch below:
float delta_x_below, delta_y_below;
float max_below_float;
int max_below = 0;
if (layer == 0)
{
// guess the lower intra octave...
const BriskLayer& l = pyramid_[0];
int s_0_0 = l.getAgastScore_5_8(x_layer - 1, y_layer - 1, 1);
max_below = s_0_0;
int s_1_0 = l.getAgastScore_5_8(x_layer, y_layer - 1, 1);
max_below = std::max(s_1_0, max_below);
int s_2_0 = l.getAgastScore_5_8(x_layer + 1, y_layer - 1, 1);
max_below = std::max(s_2_0, max_below);
int s_2_1 = l.getAgastScore_5_8(x_layer + 1, y_layer, 1);
max_below = std::max(s_2_1, max_below);
int s_1_1 = l.getAgastScore_5_8(x_layer, y_layer, 1);
max_below = std::max(s_1_1, max_below);
int s_0_1 = l.getAgastScore_5_8(x_layer - 1, y_layer, 1);
max_below = std::max(s_0_1, max_below);
int s_0_2 = l.getAgastScore_5_8(x_layer - 1, y_layer + 1, 1);
max_below = std::max(s_0_2, max_below);
int s_1_2 = l.getAgastScore_5_8(x_layer, y_layer + 1, 1);
max_below = std::max(s_1_2, max_below);
int s_2_2 = l.getAgastScore_5_8(x_layer + 1, y_layer + 1, 1);
max_below = std::max(s_2_2, max_below);
subpixel2D(s_0_0, s_0_1, s_0_2, s_1_0, s_1_1, s_1_2, s_2_0, s_2_1, s_2_2, delta_x_below, delta_y_below);
max_below_float = (float)max_below;
}
else
{
max_below_float = getScoreMaxBelow(layer, x_layer, y_layer, center, ismax, delta_x_below, delta_y_below);
if (!ismax)
return 0;
}
// get the patch on this layer:
int s_0_0 = thisLayer.getAgastScore(x_layer - 1, y_layer - 1, 1);
int s_1_0 = thisLayer.getAgastScore(x_layer, y_layer - 1, 1);
int s_2_0 = thisLayer.getAgastScore(x_layer + 1, y_layer - 1, 1);
int s_2_1 = thisLayer.getAgastScore(x_layer + 1, y_layer, 1);
int s_1_1 = thisLayer.getAgastScore(x_layer, y_layer, 1);
int s_0_1 = thisLayer.getAgastScore(x_layer - 1, y_layer, 1);
int s_0_2 = thisLayer.getAgastScore(x_layer - 1, y_layer + 1, 1);
int s_1_2 = thisLayer.getAgastScore(x_layer, y_layer + 1, 1);
int s_2_2 = thisLayer.getAgastScore(x_layer + 1, y_layer + 1, 1);
float delta_x_layer, delta_y_layer;
float max_layer = subpixel2D(s_0_0, s_0_1, s_0_2, s_1_0, s_1_1, s_1_2, s_2_0, s_2_1, s_2_2, delta_x_layer,
delta_y_layer);
// calculate the relative scale (1D maximum):
if (layer == 0)
{
scale = refine1D_2(max_below_float, std::max(float(center), max_layer), max_above, max);
}
else
scale = refine1D(max_below_float, std::max(float(center), max_layer), max_above, max);
if (scale > 1.0)
{
// interpolate the position:
const float r0 = (1.5f - scale) / .5f;
const float r1 = 1.0f - r0;
x = (r0 * delta_x_layer + r1 * delta_x_above + float(x_layer)) * thisLayer.scale() + thisLayer.offset();
y = (r0 * delta_y_layer + r1 * delta_y_above + float(y_layer)) * thisLayer.scale() + thisLayer.offset();
}
else
{
if (layer == 0)
{
// interpolate the position:
const float r0 = (scale - 0.5f) / 0.5f;
const float r_1 = 1.0f - r0;
x = r0 * delta_x_layer + r_1 * delta_x_below + float(x_layer);
y = r0 * delta_y_layer + r_1 * delta_y_below + float(y_layer);
}
else
{
// interpolate the position:
const float r0 = (scale - 0.75f) / 0.25f;
const float r_1 = 1.0f - r0;
x = (r0 * delta_x_layer + r_1 * delta_x_below + float(x_layer)) * thisLayer.scale() + thisLayer.offset();
y = (r0 * delta_y_layer + r_1 * delta_y_below + float(y_layer)) * thisLayer.scale() + thisLayer.offset();
}
}
}
else
{
// on intra
// check the patch below:
float delta_x_below, delta_y_below;
float max_below = getScoreMaxBelow(layer, x_layer, y_layer, center, ismax, delta_x_below, delta_y_below);
if (!ismax)
return 0.0f;
// get the patch on this layer:
int s_0_0 = thisLayer.getAgastScore(x_layer - 1, y_layer - 1, 1);
int s_1_0 = thisLayer.getAgastScore(x_layer, y_layer - 1, 1);
int s_2_0 = thisLayer.getAgastScore(x_layer + 1, y_layer - 1, 1);
int s_2_1 = thisLayer.getAgastScore(x_layer + 1, y_layer, 1);
int s_1_1 = thisLayer.getAgastScore(x_layer, y_layer, 1);
int s_0_1 = thisLayer.getAgastScore(x_layer - 1, y_layer, 1);
int s_0_2 = thisLayer.getAgastScore(x_layer - 1, y_layer + 1, 1);
int s_1_2 = thisLayer.getAgastScore(x_layer, y_layer + 1, 1);
int s_2_2 = thisLayer.getAgastScore(x_layer + 1, y_layer + 1, 1);
float delta_x_layer, delta_y_layer;
float max_layer = subpixel2D(s_0_0, s_0_1, s_0_2, s_1_0, s_1_1, s_1_2, s_2_0, s_2_1, s_2_2, delta_x_layer,
delta_y_layer);
// calculate the relative scale (1D maximum):
scale = refine1D_1(max_below, std::max(float(center), max_layer), max_above, max);
if (scale > 1.0)
{
// interpolate the position:
const float r0 = 4.0f - scale * 3.0f;
const float r1 = 1.0f - r0;
x = (r0 * delta_x_layer + r1 * delta_x_above + float(x_layer)) * thisLayer.scale() + thisLayer.offset();
y = (r0 * delta_y_layer + r1 * delta_y_above + float(y_layer)) * thisLayer.scale() + thisLayer.offset();
}
else
{
// interpolate the position:
const float r0 = scale * 3.0f - 2.0f;
const float r_1 = 1.0f - r0;
x = (r0 * delta_x_layer + r_1 * delta_x_below + float(x_layer)) * thisLayer.scale() + thisLayer.offset();
y = (r0 * delta_y_layer + r_1 * delta_y_below + float(y_layer)) * thisLayer.scale() + thisLayer.offset();
}
}
// calculate the absolute scale:
scale *= thisLayer.scale();
// that's it, return the refined maximum:
return max;
}
// return the maximum of score patches above or below
inline float
BriskScaleSpace::getScoreMaxAbove(const int layer, const int x_layer, const int y_layer, const int threshold,
bool& ismax, float& dx, float& dy) const
{
ismax = false;
// relevant floating point coordinates
float x_1;
float x1;
float y_1;
float y1;
// the layer above
CV_Assert(layer + 1 < layers_);
const BriskLayer& layerAbove = pyramid_[layer + 1];
if (layer % 2 == 0)
{
// octave
x_1 = float(4 * (x_layer) - 1 - 2) / 6.0f;
x1 = float(4 * (x_layer) - 1 + 2) / 6.0f;
y_1 = float(4 * (y_layer) - 1 - 2) / 6.0f;
y1 = float(4 * (y_layer) - 1 + 2) / 6.0f;
}
else
{
// intra
x_1 = float(6 * (x_layer) - 1 - 3) / 8.0f;
x1 = float(6 * (x_layer) - 1 + 3) / 8.0f;
y_1 = float(6 * (y_layer) - 1 - 3) / 8.0f;
y1 = float(6 * (y_layer) - 1 + 3) / 8.0f;
}
// check the first row
int max_x = (int)x_1 + 1;
int max_y = (int)y_1 + 1;
float tmp_max;
float maxval = (float)layerAbove.getAgastScore(x_1, y_1, 1);
if (maxval > threshold)
return 0;
for (int x = (int)x_1 + 1; x <= int(x1); x++)
{
tmp_max = (float)layerAbove.getAgastScore(float(x), y_1, 1);
if (tmp_max > threshold)
return 0;
if (tmp_max > maxval)
{
maxval = tmp_max;
max_x = x;
}
}
tmp_max = (float)layerAbove.getAgastScore(x1, y_1, 1);
if (tmp_max > threshold)
return 0;
if (tmp_max > maxval)
{
maxval = tmp_max;
max_x = int(x1);
}
// middle rows
for (int y = (int)y_1 + 1; y <= int(y1); y++)
{
tmp_max = (float)layerAbove.getAgastScore(x_1, float(y), 1);
if (tmp_max > threshold)
return 0;
if (tmp_max > maxval)
{
maxval = tmp_max;
max_x = int(x_1 + 1);
max_y = y;
}
for (int x = (int)x_1 + 1; x <= int(x1); x++)
{
tmp_max = (float)layerAbove.getAgastScore(x, y, 1);
if (tmp_max > threshold)
return 0;
if (tmp_max > maxval)
{
maxval = tmp_max;
max_x = x;
max_y = y;
}
}
tmp_max = (float)layerAbove.getAgastScore(x1, float(y), 1);
if (tmp_max > threshold)
return 0;
if (tmp_max > maxval)
{
maxval = tmp_max;
max_x = int(x1);
max_y = y;
}
}
// bottom row
tmp_max = (float)layerAbove.getAgastScore(x_1, y1, 1);
if (tmp_max > maxval)
{
maxval = tmp_max;
max_x = int(x_1 + 1);
max_y = int(y1);
}
for (int x = (int)x_1 + 1; x <= int(x1); x++)
{
tmp_max = (float)layerAbove.getAgastScore(float(x), y1, 1);
if (tmp_max > maxval)
{
maxval = tmp_max;
max_x = x;
max_y = int(y1);
}
}
tmp_max = (float)layerAbove.getAgastScore(x1, y1, 1);
if (tmp_max > maxval)
{
maxval = tmp_max;
max_x = int(x1);
max_y = int(y1);
}
//find dx/dy:
int s_0_0 = layerAbove.getAgastScore(max_x - 1, max_y - 1, 1);
int s_1_0 = layerAbove.getAgastScore(max_x, max_y - 1, 1);
int s_2_0 = layerAbove.getAgastScore(max_x + 1, max_y - 1, 1);
int s_2_1 = layerAbove.getAgastScore(max_x + 1, max_y, 1);
int s_1_1 = layerAbove.getAgastScore(max_x, max_y, 1);
int s_0_1 = layerAbove.getAgastScore(max_x - 1, max_y, 1);
int s_0_2 = layerAbove.getAgastScore(max_x - 1, max_y + 1, 1);
int s_1_2 = layerAbove.getAgastScore(max_x, max_y + 1, 1);
int s_2_2 = layerAbove.getAgastScore(max_x + 1, max_y + 1, 1);
float dx_1, dy_1;
float refined_max = subpixel2D(s_0_0, s_0_1, s_0_2, s_1_0, s_1_1, s_1_2, s_2_0, s_2_1, s_2_2, dx_1, dy_1);
// calculate dx/dy in above coordinates
float real_x = float(max_x) + dx_1;
float real_y = float(max_y) + dy_1;
bool returnrefined = true;
if (layer % 2 == 0)
{
dx = (real_x * 6.0f + 1.0f) / 4.0f - float(x_layer);
dy = (real_y * 6.0f + 1.0f) / 4.0f - float(y_layer);
}
else
{
dx = (real_x * 8.0f + 1.0f) / 6.0f - float(x_layer);
dy = (real_y * 8.0f + 1.0f) / 6.0f - float(y_layer);
}
// saturate
if (dx > 1.0f)
{
dx = 1.0f;
returnrefined = false;
}
if (dx < -1.0f)
{
dx = -1.0f;
returnrefined = false;
}
if (dy > 1.0f)
{
dy = 1.0f;
returnrefined = false;
}
if (dy < -1.0f)
{
dy = -1.0f;
returnrefined = false;
}
// done and ok.
ismax = true;
if (returnrefined)
{
return std::max(refined_max, maxval);
}
return maxval;
}
inline float
BriskScaleSpace::getScoreMaxBelow(const int layer, const int x_layer, const int y_layer, const int threshold,
bool& ismax, float& dx, float& dy) const
{
ismax = false;
// relevant floating point coordinates
float x_1;
float x1;
float y_1;
float y1;
if (layer % 2 == 0)
{
// octave
x_1 = float(8 * (x_layer) + 1 - 4) / 6.0f;
x1 = float(8 * (x_layer) + 1 + 4) / 6.0f;
y_1 = float(8 * (y_layer) + 1 - 4) / 6.0f;
y1 = float(8 * (y_layer) + 1 + 4) / 6.0f;
}
else
{
x_1 = float(6 * (x_layer) + 1 - 3) / 4.0f;
x1 = float(6 * (x_layer) + 1 + 3) / 4.0f;
y_1 = float(6 * (y_layer) + 1 - 3) / 4.0f;
y1 = float(6 * (y_layer) + 1 + 3) / 4.0f;
}
// the layer below
CV_Assert(layer > 0);
const BriskLayer& layerBelow = pyramid_[layer - 1];
// check the first row
int max_x = (int)x_1 + 1;
int max_y = (int)y_1 + 1;
float tmp_max;
float max = (float)layerBelow.getAgastScore(x_1, y_1, 1);
if (max > threshold)
return 0;
for (int x = (int)x_1 + 1; x <= int(x1); x++)
{
tmp_max = (float)layerBelow.getAgastScore(float(x), y_1, 1);
if (tmp_max > threshold)
return 0;
if (tmp_max > max)
{
max = tmp_max;
max_x = x;
}
}
tmp_max = (float)layerBelow.getAgastScore(x1, y_1, 1);
if (tmp_max > threshold)
return 0;
if (tmp_max > max)
{
max = tmp_max;
max_x = int(x1);
}
// middle rows
for (int y = (int)y_1 + 1; y <= int(y1); y++)
{
tmp_max = (float)layerBelow.getAgastScore(x_1, float(y), 1);
if (tmp_max > threshold)
return 0;
if (tmp_max > max)
{
max = tmp_max;
max_x = int(x_1 + 1);
max_y = y;
}
for (int x = (int)x_1 + 1; x <= int(x1); x++)
{
tmp_max = (float)layerBelow.getAgastScore(x, y, 1);
if (tmp_max > threshold)
return 0;
if (tmp_max == max)
{
const int t1 = 2
* (layerBelow.getAgastScore(x - 1, y, 1) + layerBelow.getAgastScore(x + 1, y, 1)
+ layerBelow.getAgastScore(x, y + 1, 1) + layerBelow.getAgastScore(x, y - 1, 1))
+ (layerBelow.getAgastScore(x + 1, y + 1, 1) + layerBelow.getAgastScore(x - 1, y + 1, 1)
+ layerBelow.getAgastScore(x + 1, y - 1, 1) + layerBelow.getAgastScore(x - 1, y - 1, 1));
const int t2 = 2
* (layerBelow.getAgastScore(max_x - 1, max_y, 1) + layerBelow.getAgastScore(max_x + 1, max_y, 1)
+ layerBelow.getAgastScore(max_x, max_y + 1, 1) + layerBelow.getAgastScore(max_x, max_y - 1, 1))
+ (layerBelow.getAgastScore(max_x + 1, max_y + 1, 1) + layerBelow.getAgastScore(max_x - 1,
max_y + 1, 1)
+ layerBelow.getAgastScore(max_x + 1, max_y - 1, 1)
+ layerBelow.getAgastScore(max_x - 1, max_y - 1, 1));
if (t1 > t2)
{
max_x = x;
max_y = y;
}
}
if (tmp_max > max)
{
max = tmp_max;
max_x = x;
max_y = y;
}
}
tmp_max = (float)layerBelow.getAgastScore(x1, float(y), 1);
if (tmp_max > threshold)
return 0;
if (tmp_max > max)
{
max = tmp_max;
max_x = int(x1);
max_y = y;
}
}
// bottom row
tmp_max = (float)layerBelow.getAgastScore(x_1, y1, 1);
if (tmp_max > max)
{
max = tmp_max;
max_x = int(x_1 + 1);
max_y = int(y1);
}
for (int x = (int)x_1 + 1; x <= int(x1); x++)
{
tmp_max = (float)layerBelow.getAgastScore(float(x), y1, 1);
if (tmp_max > max)
{
max = tmp_max;
max_x = x;
max_y = int(y1);
}
}
tmp_max = (float)layerBelow.getAgastScore(x1, y1, 1);
if (tmp_max > max)
{
max = tmp_max;
max_x = int(x1);
max_y = int(y1);
}
//find dx/dy:
int s_0_0 = layerBelow.getAgastScore(max_x - 1, max_y - 1, 1);
int s_1_0 = layerBelow.getAgastScore(max_x, max_y - 1, 1);
int s_2_0 = layerBelow.getAgastScore(max_x + 1, max_y - 1, 1);
int s_2_1 = layerBelow.getAgastScore(max_x + 1, max_y, 1);
int s_1_1 = layerBelow.getAgastScore(max_x, max_y, 1);
int s_0_1 = layerBelow.getAgastScore(max_x - 1, max_y, 1);
int s_0_2 = layerBelow.getAgastScore(max_x - 1, max_y + 1, 1);
int s_1_2 = layerBelow.getAgastScore(max_x, max_y + 1, 1);
int s_2_2 = layerBelow.getAgastScore(max_x + 1, max_y + 1, 1);
float dx_1, dy_1;
float refined_max = subpixel2D(s_0_0, s_0_1, s_0_2, s_1_0, s_1_1, s_1_2, s_2_0, s_2_1, s_2_2, dx_1, dy_1);
// calculate dx/dy in above coordinates
float real_x = float(max_x) + dx_1;
float real_y = float(max_y) + dy_1;
bool returnrefined = true;
if (layer % 2 == 0)
{
dx = (float)((real_x * 6.0 + 1.0) / 8.0) - float(x_layer);
dy = (float)((real_y * 6.0 + 1.0) / 8.0) - float(y_layer);
}
else
{
dx = (float)((real_x * 4.0 - 1.0) / 6.0) - float(x_layer);
dy = (float)((real_y * 4.0 - 1.0) / 6.0) - float(y_layer);
}
// saturate
if (dx > 1.0)
{
dx = 1.0f;
returnrefined = false;
}
if (dx < -1.0f)
{
dx = -1.0f;
returnrefined = false;
}
if (dy > 1.0f)
{
dy = 1.0f;
returnrefined = false;
}
if (dy < -1.0f)
{
dy = -1.0f;
returnrefined = false;
}
// done and ok.
ismax = true;
if (returnrefined)
{
return std::max(refined_max, max);
}
return max;
}
inline float
BriskScaleSpace::refine1D(const float s_05, const float s0, const float s05, float& max) const
{
int i_05 = int(1024.0 * s_05 + 0.5);
int i0 = int(1024.0 * s0 + 0.5);
int i05 = int(1024.0 * s05 + 0.5);
// 16.0000 -24.0000 8.0000
// -40.0000 54.0000 -14.0000
// 24.0000 -27.0000 6.0000
int three_a = 16 * i_05 - 24 * i0 + 8 * i05;
// second derivative must be negative:
if (three_a >= 0)
{
if (s0 >= s_05 && s0 >= s05)
{
max = s0;
return 1.0f;
}
if (s_05 >= s0 && s_05 >= s05)
{
max = s_05;
return 0.75f;
}
if (s05 >= s0 && s05 >= s_05)
{
max = s05;
return 1.5f;
}
}
int three_b = -40 * i_05 + 54 * i0 - 14 * i05;
// calculate max location:
float ret_val = -float(three_b) / float(2 * three_a);
// saturate and return
if (ret_val < 0.75)
ret_val = 0.75;
else if (ret_val > 1.5)
ret_val = 1.5; // allow to be slightly off bounds ...?
int three_c = +24 * i_05 - 27 * i0 + 6 * i05;
max = float(three_c) + float(three_a) * ret_val * ret_val + float(three_b) * ret_val;
max /= 3072.0f;
return ret_val;
}
inline float
BriskScaleSpace::refine1D_1(const float s_05, const float s0, const float s05, float& max) const
{
int i_05 = int(1024.0 * s_05 + 0.5);
int i0 = int(1024.0 * s0 + 0.5);
int i05 = int(1024.0 * s05 + 0.5);
// 4.5000 -9.0000 4.5000
//-10.5000 18.0000 -7.5000
// 6.0000 -8.0000 3.0000
int two_a = 9 * i_05 - 18 * i0 + 9 * i05;
// second derivative must be negative:
if (two_a >= 0)
{
if (s0 >= s_05 && s0 >= s05)
{
max = s0;
return 1.0f;
}
if (s_05 >= s0 && s_05 >= s05)
{
max = s_05;
return 0.6666666666666666666666666667f;
}
if (s05 >= s0 && s05 >= s_05)
{
max = s05;
return 1.3333333333333333333333333333f;
}
}
int two_b = -21 * i_05 + 36 * i0 - 15 * i05;
// calculate max location:
float ret_val = -float(two_b) / float(2 * two_a);
// saturate and return
if (ret_val < 0.6666666666666666666666666667f)
ret_val = 0.666666666666666666666666667f;
else if (ret_val > 1.33333333333333333333333333f)
ret_val = 1.333333333333333333333333333f;
int two_c = +12 * i_05 - 16 * i0 + 6 * i05;
max = float(two_c) + float(two_a) * ret_val * ret_val + float(two_b) * ret_val;
max /= 2048.0f;
return ret_val;
}
inline float
BriskScaleSpace::refine1D_2(const float s_05, const float s0, const float s05, float& max) const
{
int i_05 = int(1024.0 * s_05 + 0.5);
int i0 = int(1024.0 * s0 + 0.5);
int i05 = int(1024.0 * s05 + 0.5);
// 18.0000 -30.0000 12.0000
// -45.0000 65.0000 -20.0000
// 27.0000 -30.0000 8.0000
int a = 2 * i_05 - 4 * i0 + 2 * i05;
// second derivative must be negative:
if (a >= 0)
{
if (s0 >= s_05 && s0 >= s05)
{
max = s0;
return 1.0f;
}
if (s_05 >= s0 && s_05 >= s05)
{
max = s_05;
return 0.7f;
}
if (s05 >= s0 && s05 >= s_05)
{
max = s05;
return 1.5f;
}
}
int b = -5 * i_05 + 8 * i0 - 3 * i05;
// calculate max location:
float ret_val = -float(b) / float(2 * a);
// saturate and return
if (ret_val < 0.7f)
ret_val = 0.7f;
else if (ret_val > 1.5f)
ret_val = 1.5f; // allow to be slightly off bounds ...?
int c = +3 * i_05 - 3 * i0 + 1 * i05;
max = float(c) + float(a) * ret_val * ret_val + float(b) * ret_val;
max /= 1024;
return ret_val;
}
inline float
BriskScaleSpace::subpixel2D(const int s_0_0, const int s_0_1, const int s_0_2, const int s_1_0, const int s_1_1,
const int s_1_2, const int s_2_0, const int s_2_1, const int s_2_2, float& delta_x,
float& delta_y) const
{
// the coefficients of the 2d quadratic function least-squares fit:
int tmp1 = s_0_0 + s_0_2 - 2 * s_1_1 + s_2_0 + s_2_2;
int coeff1 = 3 * (tmp1 + s_0_1 - ((s_1_0 + s_1_2) << 1) + s_2_1);
int coeff2 = 3 * (tmp1 - ((s_0_1 + s_2_1) << 1) + s_1_0 + s_1_2);
int tmp2 = s_0_2 - s_2_0;
int tmp3 = (s_0_0 + tmp2 - s_2_2);
int tmp4 = tmp3 - 2 * tmp2;
int coeff3 = -3 * (tmp3 + s_0_1 - s_2_1);
int coeff4 = -3 * (tmp4 + s_1_0 - s_1_2);
int coeff5 = (s_0_0 - s_0_2 - s_2_0 + s_2_2) << 2;
int coeff6 = -(s_0_0 + s_0_2 - ((s_1_0 + s_0_1 + s_1_2 + s_2_1) << 1) - 5 * s_1_1 + s_2_0 + s_2_2) << 1;
// 2nd derivative test:
int H_det = 4 * coeff1 * coeff2 - coeff5 * coeff5;
if (H_det == 0)
{
delta_x = 0.0f;
delta_y = 0.0f;
return float(coeff6) / 18.0f;
}
if (!(H_det > 0 && coeff1 < 0))
{
// The maximum must be at the one of the 4 patch corners.
int tmp_max = coeff3 + coeff4 + coeff5;
delta_x = 1.0f;
delta_y = 1.0f;
int tmp = -coeff3 + coeff4 - coeff5;
if (tmp > tmp_max)
{
tmp_max = tmp;
delta_x = -1.0f;
delta_y = 1.0f;
}
tmp = coeff3 - coeff4 - coeff5;
if (tmp > tmp_max)
{
tmp_max = tmp;
delta_x = 1.0f;
delta_y = -1.0f;
}
tmp = -coeff3 - coeff4 + coeff5;
if (tmp > tmp_max)
{
tmp_max = tmp;
delta_x = -1.0f;
delta_y = -1.0f;
}
return float(tmp_max + coeff1 + coeff2 + coeff6) / 18.0f;
}
// this is hopefully the normal outcome of the Hessian test
delta_x = float(2 * coeff2 * coeff3 - coeff4 * coeff5) / float(-H_det);
delta_y = float(2 * coeff1 * coeff4 - coeff3 * coeff5) / float(-H_det);
// TODO: this is not correct, but easy, so perform a real boundary maximum search:
bool tx = false;
bool tx_ = false;
bool ty = false;
bool ty_ = false;
if (delta_x > 1.0)
tx = true;
else if (delta_x < -1.0)
tx_ = true;
if (delta_y > 1.0)
ty = true;
if (delta_y < -1.0)
ty_ = true;
if (tx || tx_ || ty || ty_)
{
// get two candidates:
float delta_x1 = 0.0f, delta_x2 = 0.0f, delta_y1 = 0.0f, delta_y2 = 0.0f;
if (tx)
{
delta_x1 = 1.0f;
delta_y1 = -float(coeff4 + coeff5) / float(2 * coeff2);
if (delta_y1 > 1.0f)
delta_y1 = 1.0f;
else if (delta_y1 < -1.0f)
delta_y1 = -1.0f;
}
else if (tx_)
{
delta_x1 = -1.0f;
delta_y1 = -float(coeff4 - coeff5) / float(2 * coeff2);
if (delta_y1 > 1.0f)
delta_y1 = 1.0f;
else if (delta_y1 < -1.0)
delta_y1 = -1.0f;
}
if (ty)
{
delta_y2 = 1.0f;
delta_x2 = -float(coeff3 + coeff5) / float(2 * coeff1);
if (delta_x2 > 1.0f)
delta_x2 = 1.0f;
else if (delta_x2 < -1.0f)
delta_x2 = -1.0f;
}
else if (ty_)
{
delta_y2 = -1.0f;
delta_x2 = -float(coeff3 - coeff5) / float(2 * coeff1);
if (delta_x2 > 1.0f)
delta_x2 = 1.0f;
else if (delta_x2 < -1.0f)
delta_x2 = -1.0f;
}
// insert both options for evaluation which to pick
float max1 = (coeff1 * delta_x1 * delta_x1 + coeff2 * delta_y1 * delta_y1 + coeff3 * delta_x1 + coeff4 * delta_y1
+ coeff5 * delta_x1 * delta_y1 + coeff6)
/ 18.0f;
float max2 = (coeff1 * delta_x2 * delta_x2 + coeff2 * delta_y2 * delta_y2 + coeff3 * delta_x2 + coeff4 * delta_y2
+ coeff5 * delta_x2 * delta_y2 + coeff6)
/ 18.0f;
if (max1 > max2)
{
delta_x = delta_x1;
delta_y = delta_y1;
return max1;
}
else
{
delta_x = delta_x2;
delta_y = delta_y2;
return max2;
}
}
// this is the case of the maximum inside the boundaries:
return (coeff1 * delta_x * delta_x + coeff2 * delta_y * delta_y + coeff3 * delta_x + coeff4 * delta_y
+ coeff5 * delta_x * delta_y + coeff6)
/ 18.0f;
}
// construct a layer
BriskLayer::BriskLayer(const cv::Mat& img_in, float scale_in, float offset_in)
{
img_ = img_in;
scores_ = cv::Mat_<uchar>::zeros(img_in.rows, img_in.cols);
// attention: this means that the passed image reference must point to persistent memory
scale_ = scale_in;
offset_ = offset_in;
// create an agast detector
oast_9_16_ = AgastFeatureDetector::create(1, false, AgastFeatureDetector::OAST_9_16);
makeAgastOffsets(pixel_5_8_, (int)img_.step, AgastFeatureDetector::AGAST_5_8);
makeAgastOffsets(pixel_9_16_, (int)img_.step, AgastFeatureDetector::OAST_9_16);
}
// derive a layer
BriskLayer::BriskLayer(const BriskLayer& layer, int mode)
{
if (mode == CommonParams::HALFSAMPLE)
{
img_.create(layer.img().rows / 2, layer.img().cols / 2, CV_8U);
halfsample(layer.img(), img_);
scale_ = layer.scale() * 2;
offset_ = 0.5f * scale_ - 0.5f;
}
else
{
img_.create(2 * (layer.img().rows / 3), 2 * (layer.img().cols / 3), CV_8U);
twothirdsample(layer.img(), img_);
scale_ = layer.scale() * 1.5f;
offset_ = 0.5f * scale_ - 0.5f;
}
scores_ = cv::Mat::zeros(img_.rows, img_.cols, CV_8U);
oast_9_16_ = AgastFeatureDetector::create(1, false, AgastFeatureDetector::OAST_9_16);
makeAgastOffsets(pixel_5_8_, (int)img_.step, AgastFeatureDetector::AGAST_5_8);
makeAgastOffsets(pixel_9_16_, (int)img_.step, AgastFeatureDetector::OAST_9_16);
}
// Agast
// wraps the agast class
void
BriskLayer::getAgastPoints(int threshold, std::vector<KeyPoint>& keypoints)
{
oast_9_16_->setThreshold(threshold);
oast_9_16_->detect(img_, keypoints);
// also write scores
const size_t num = keypoints.size();
for (size_t i = 0; i < num; i++)
scores_((int)keypoints[i].pt.y, (int)keypoints[i].pt.x) = saturate_cast<uchar>(keypoints[i].response);
}
inline int
BriskLayer::getAgastScore(int x, int y, int threshold) const
{
if (x < 3 || y < 3)
return 0;
if (x >= img_.cols - 3 || y >= img_.rows - 3)
return 0;
uchar& score = (uchar&)scores_(y, x);
if (score > 2)
{
return score;
}
score = (uchar)agast_cornerScore<AgastFeatureDetector::OAST_9_16>(&img_.at<uchar>(y, x), pixel_9_16_, threshold - 1);
if (score < threshold)
score = 0;
return score;
}
inline int
BriskLayer::getAgastScore_5_8(int x, int y, int threshold) const
{
if (x < 2 || y < 2)
return 0;
if (x >= img_.cols - 2 || y >= img_.rows - 2)
return 0;
int score = agast_cornerScore<AgastFeatureDetector::AGAST_5_8>(&img_.at<uchar>(y, x), pixel_5_8_, threshold - 1);
if (score < threshold)
score = 0;
return score;
}
inline int
BriskLayer::getAgastScore(float xf, float yf, int threshold_in, float scale_in) const
{
if (scale_in <= 1.0f)
{
// just do an interpolation inside the layer
const int x = int(xf);
const float rx1 = xf - float(x);
const float rx = 1.0f - rx1;
const int y = int(yf);
const float ry1 = yf - float(y);
const float ry = 1.0f - ry1;
return (uchar)(rx * ry * getAgastScore(x, y, threshold_in) + rx1 * ry * getAgastScore(x + 1, y, threshold_in)
+ rx * ry1 * getAgastScore(x, y + 1, threshold_in) + rx1 * ry1 * getAgastScore(x + 1, y + 1, threshold_in));
}
else
{
// this means we overlap area smoothing
const float halfscale = scale_in / 2.0f;
// get the scores first:
for (int x = int(xf - halfscale); x <= int(xf + halfscale + 1.0f); x++)
{
for (int y = int(yf - halfscale); y <= int(yf + halfscale + 1.0f); y++)
{
getAgastScore(x, y, threshold_in);
}
}
// get the smoothed value
return value(scores_, xf, yf, scale_in);
}
}
// access gray values (smoothed/interpolated)
inline int
BriskLayer::value(const cv::Mat& mat, float xf, float yf, float scale_in) const
{
CV_Assert(!mat.empty());
// get the position
const int x = cvFloor(xf);
const int y = cvFloor(yf);
const cv::Mat& image = mat;
const int& imagecols = image.cols;
// get the sigma_half:
const float sigma_half = scale_in / 2;
const float area = 4.0f * sigma_half * sigma_half;
// calculate output:
int ret_val;
if (sigma_half < 0.5)
{
//interpolation multipliers:
const int r_x = (int)((xf - x) * 1024);
const int r_y = (int)((yf - y) * 1024);
const int r_x_1 = (1024 - r_x);
const int r_y_1 = (1024 - r_y);
const uchar* ptr = image.ptr() + x + y * imagecols;
// just interpolate:
ret_val = (r_x_1 * r_y_1 * int(*ptr));
ptr++;
ret_val += (r_x * r_y_1 * int(*ptr));
ptr += imagecols;
ret_val += (r_x * r_y * int(*ptr));
ptr--;
ret_val += (r_x_1 * r_y * int(*ptr));
return 0xFF & ((ret_val + 512) / 1024 / 1024);
}
// this is the standard case (simple, not speed optimized yet):
// scaling:
const int scaling = (int)(4194304.0f / area);
const int scaling2 = (int)(float(scaling) * area / 1024.0f);
CV_Assert(scaling2 != 0);
// calculate borders
const float x_1 = xf - sigma_half;
const float x1 = xf + sigma_half;
const float y_1 = yf - sigma_half;
const float y1 = yf + sigma_half;
const int x_left = int(x_1 + 0.5);
const int y_top = int(y_1 + 0.5);
const int x_right = int(x1 + 0.5);
const int y_bottom = int(y1 + 0.5);
// overlap area - multiplication factors:
const float r_x_1 = float(x_left) - x_1 + 0.5f;
const float r_y_1 = float(y_top) - y_1 + 0.5f;
const float r_x1 = x1 - float(x_right) + 0.5f;
const float r_y1 = y1 - float(y_bottom) + 0.5f;
const int dx = x_right - x_left - 1;
const int dy = y_bottom - y_top - 1;
const int A = (int)((r_x_1 * r_y_1) * scaling);
const int B = (int)((r_x1 * r_y_1) * scaling);
const int C = (int)((r_x1 * r_y1) * scaling);
const int D = (int)((r_x_1 * r_y1) * scaling);
const int r_x_1_i = (int)(r_x_1 * scaling);
const int r_y_1_i = (int)(r_y_1 * scaling);
const int r_x1_i = (int)(r_x1 * scaling);
const int r_y1_i = (int)(r_y1 * scaling);
// now the calculation:
const uchar* ptr = image.ptr() + x_left + imagecols * y_top;
// first row:
ret_val = A * int(*ptr);
ptr++;
const uchar* end1 = ptr + dx;
for (; ptr < end1; ptr++)
{
ret_val += r_y_1_i * int(*ptr);
}
ret_val += B * int(*ptr);
// middle ones:
ptr += imagecols - dx - 1;
const uchar* end_j = ptr + dy * imagecols;
for (; ptr < end_j; ptr += imagecols - dx - 1)
{
ret_val += r_x_1_i * int(*ptr);
ptr++;
const uchar* end2 = ptr + dx;
for (; ptr < end2; ptr++)
{
ret_val += int(*ptr) * scaling;
}
ret_val += r_x1_i * int(*ptr);
}
// last row:
ret_val += D * int(*ptr);
ptr++;
const uchar* end3 = ptr + dx;
for (; ptr < end3; ptr++)
{
ret_val += r_y1_i * int(*ptr);
}
ret_val += C * int(*ptr);
return 0xFF & ((ret_val + scaling2 / 2) / scaling2 / 1024);
}
// half sampling
inline void
BriskLayer::halfsample(const cv::Mat& srcimg, cv::Mat& dstimg)
{
// make sure the destination image is of the right size:
CV_Assert(srcimg.cols / 2 == dstimg.cols);
CV_Assert(srcimg.rows / 2 == dstimg.rows);
// handle non-SSE case
resize(srcimg, dstimg, dstimg.size(), 0, 0, INTER_AREA);
}
inline void
BriskLayer::twothirdsample(const cv::Mat& srcimg, cv::Mat& dstimg)
{
// make sure the destination image is of the right size:
CV_Assert((srcimg.cols / 3) * 2 == dstimg.cols);
CV_Assert((srcimg.rows / 3) * 2 == dstimg.rows);
resize(srcimg, dstimg, dstimg.size(), 0, 0, INTER_AREA);
}
Ptr<BRISK> BRISK::create(int thresh, int octaves, float patternScale)
{
return makePtr<BRISK_Impl>(thresh, octaves, patternScale);
}
// custom setup
Ptr<BRISK> BRISK::create(const std::vector<float> &radiusList, const std::vector<int> &numberList,
float dMax, float dMin, const std::vector<int>& indexChange)
{
return makePtr<BRISK_Impl>(radiusList, numberList, dMax, dMin, indexChange);
}
Ptr<BRISK> BRISK::create(int thresh, int octaves, const std::vector<float> &radiusList,
const std::vector<int> &numberList, float dMax, float dMin,
const std::vector<int>& indexChange)
{
return makePtr<BRISK_Impl>(thresh, octaves, radiusList, numberList, dMax, dMin, indexChange);
}
String BRISK::getDefaultName() const
{
return (Feature2D::getDefaultName() + ".BRISK");
}
}