/**
@brief Detect regions on the image and compute their attributes (description)
@param image Image.
@param regions The detected regions and attributes (the caller must delete the allocated data)
@param mask 8-bit gray image for keypoint filtering (optional).
Non-zero values depict the region of interest.
*/
bool Describe(const image::Image<unsigned char>& image,
std::unique_ptr<Regions> ®ions,
const image::Image<unsigned char> * mask = nullptr)
{
// Convert for opencv
cv::Mat img;
cv::eigen2cv(image.GetMat(), img);
// Convert mask image into cv::Mat
cv::Mat m_mask;
if(mask != nullptr) {
cv::eigen2cv(mask->GetMat(), m_mask);
}
// Create a SIFT detector
std::vector< cv::KeyPoint > v_keypoints;
cv::Mat m_desc;
cv::Ptr<cv::Feature2D> siftdetector = cv::xfeatures2d::SIFT::create();
// Process SIFT computation
siftdetector->detectAndCompute(img, m_mask, v_keypoints, m_desc);
Allocate(regions);
// Build alias to cached data
SIFT_Regions * regionsCasted = dynamic_cast<SIFT_Regions*>(regions.get());
// reserve some memory for faster keypoint saving
regionsCasted->Features().reserve(v_keypoints.size());
regionsCasted->Descriptors().reserve(v_keypoints.size());
// Prepare a column vector with the sum of each descriptor
cv::Mat m_siftsum;
cv::reduce(m_desc, m_siftsum, 1, cv::REDUCE_SUM);
// Copy keypoints and descriptors in the regions
int cpt = 0;
for(std::vector< cv::KeyPoint >::const_iterator i_kp = v_keypoints.begin();
i_kp != v_keypoints.end();
++i_kp, ++cpt)
{
SIOPointFeature feat((*i_kp).pt.x, (*i_kp).pt.y, (*i_kp).size, (*i_kp).angle);
regionsCasted->Features().push_back(feat);
Descriptor<unsigned char, 128> desc;
for(int j = 0; j < 128; j++)
{
desc[j] = static_cast<unsigned char>(512.0*sqrt(m_desc.at<float>(cpt, j)/m_siftsum.at<float>(cpt, 0)));
}
regionsCasted->Descriptors().push_back(desc);
}
return true;
};
/**
@brief Detect regions on the image and compute their attributes (description)
@param image Image.
@param regions The detected regions and attributes (the caller must delete the allocated data)
@param mask 8-bit gray image for keypoint filtering (optional).
Non-zero values depict the region of interest.
*/
bool Describe
(
const image::Image<unsigned char>& image,
std::unique_ptr<Regions> ®ions,
const image::Image<unsigned char> * mask = nullptr
) override
{
const int w = image.Width(), h = image.Height();
// Convert to float in range [0;1]
const image::Image<float> If(image.GetMat().cast<float>()/255.0f);
// compute sift keypoints
Allocate(regions);
// Build alias to cached data
SIFT_Regions * regionsCasted = dynamic_cast<SIFT_Regions*>(regions.get());
{
using namespace openMVG::features::sift;
const int supplementary_images = 3;
// => in order to ensure each gaussian slice is used in the process 3 extra images are required:
// +1 for dog computation
// +2 for 3d discrete extrema definition
HierarchicalGaussianScaleSpace octave_gen(
params_.num_octaves_,
params_.num_scales_,
(params_.first_octave_ == -1)
? GaussianScaleSpaceParams(1.6f/2.0f, 1.0f/2.0f, 0.5f, supplementary_images)
: GaussianScaleSpaceParams(1.6f, 1.0f, 0.5f, supplementary_images));
octave_gen.SetImage( If );
std::vector<Keypoint> keypoints;
keypoints.reserve(5000);
Octave octave;
while ( octave_gen.NextOctave( octave ) )
{
std::vector< Keypoint > keys;
// Find Keypoints
SIFT_KeypointExtractor keypointDetector(
params_.peak_threshold_ / octave_gen.NbSlice(),
params_.edge_threshold_);
keypointDetector(octave, keys);
// Find Keypoints orientation and compute their description
Sift_DescriptorExtractor descriptorExtractor;
descriptorExtractor(octave, keys);
// Concatenate the found keypoints
std::move(keys.begin(), keys.end(), std::back_inserter(keypoints));
}
for (const auto & k : keypoints)
{
// Feature masking
if (mask)
{
const image::Image<unsigned char> & maskIma = *mask;
if (maskIma(k.y, k.x) == 0)
continue;
}
Descriptor<unsigned char, 128> descriptor;
descriptor << (k.descr.cast<unsigned char>());
{
regionsCasted->Descriptors().emplace_back(descriptor);
regionsCasted->Features().emplace_back(k.x, k.y, k.sigma, k.theta);
}
}
}
return true;
};
/**
@brief Detect regions on the image and compute their attributes (description)
@param image Image.
@param regions The detected regions and attributes (the caller must delete the allocated data)
@param mask 8-bit gray image for keypoint filtering (optional).
Non-zero values depict the region of interest.
*/
bool Describe(const image::Image<unsigned char>& image,
std::unique_ptr<Regions> ®ions,
const image::Image<unsigned char> * mask = NULL)
{
const int w = image.Width(), h = image.Height();
//Convert to float
const image::Image<float> If(image.GetMat().cast<float>());
VlSiftFilt *filt = vl_sift_new(w, h,
_params._num_octaves, _params._num_scales, _params._first_octave);
if (_params._edge_threshold >= 0)
vl_sift_set_edge_thresh(filt, _params._edge_threshold);
if (_params._peak_threshold >= 0)
vl_sift_set_peak_thresh(filt, 255*_params._peak_threshold/_params._num_scales);
Descriptor<vl_sift_pix, 128> descr;
Descriptor<unsigned char, 128> descriptor;
// Process SIFT computation
vl_sift_process_first_octave(filt, If.data());
Allocate(regions);
// Build alias to cached data
SIFT_Regions * regionsCasted = dynamic_cast<SIFT_Regions*>(regions.get());
// reserve some memory for faster keypoint saving
regionsCasted->Features().reserve(2000);
regionsCasted->Descriptors().reserve(2000);
while (true) {
vl_sift_detect(filt);
VlSiftKeypoint const *keys = vl_sift_get_keypoints(filt);
const int nkeys = vl_sift_get_nkeypoints(filt);
// Update gradient before launching parallel extraction
vl_sift_update_gradient(filt);
#ifdef OPENMVG_USE_OPENMP
#pragma omp parallel for private(descr, descriptor)
#endif
for (int i = 0; i < nkeys; ++i) {
// Feature masking
if (mask)
{
const image::Image<unsigned char> & maskIma = *mask;
if (maskIma(keys[i].y, keys[i].x) == 0)
continue;
}
double angles [4] = {0.0, 0.0, 0.0, 0.0};
int nangles = 1; // by default (1 upright feature)
if (_bOrientation)
{ // compute from 1 to 4 orientations
nangles = vl_sift_calc_keypoint_orientations(filt, angles, keys+i);
}
for (int q=0 ; q < nangles ; ++q) {
vl_sift_calc_keypoint_descriptor(filt, &descr[0], keys+i, angles[q]);
const SIOPointFeature fp(keys[i].x, keys[i].y,
keys[i].sigma, static_cast<float>(angles[q]));
siftDescToUChar(&descr[0], descriptor, _params._root_sift);
#ifdef OPENMVG_USE_OPENMP
#pragma omp critical
#endif
{
regionsCasted->Descriptors().push_back(descriptor);
regionsCasted->Features().push_back(fp);
}
}
}
if (vl_sift_process_next_octave(filt))
break; // Last octave
}
vl_sift_delete(filt);
return true;
};
