/**
@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,
OPENMVG_UNIQUE_PTR<Regions> ®ions,
const image::Image<unsigned char> * mask = NULL)
{
_params._options.fDesc_factor =
(_params._eAkazeDescriptor == AKAZE_MSURF ||
_params._eAkazeDescriptor == AKAZE_LIOP) ? 10.f*sqrtf(2.f)
: 11.f*sqrtf(2.f); // MLDB
AKAZE akaze(image, _params._options);
akaze.Compute_AKAZEScaleSpace();
std::vector<AKAZEKeypoint> kpts;
kpts.reserve(5000);
akaze.Feature_Detection(kpts);
akaze.Do_Subpixel_Refinement(kpts);
Allocate(regions);
switch(_params._eAkazeDescriptor)
{
case AKAZE_MSURF:
{
// Build alias to cached data
AKAZE_Float_Regions * regionsCasted = dynamic_cast<AKAZE_Float_Regions*>(regions.get());
regionsCasted->Features().resize(kpts.size());
regionsCasted->Descriptors().resize(kpts.size());
#ifdef OPENMVG_USE_OPENMP
#pragma omp parallel for
#endif
for (int i = 0; i < static_cast<int>(kpts.size()); ++i)
{
AKAZEKeypoint ptAkaze = kpts[i];
// Feature masking
if (mask)
{
const image::Image<unsigned char> & maskIma = *mask;
if (maskIma(ptAkaze.y, ptAkaze.x) > 0)
continue;
}
const TEvolution & cur_slice = akaze.getSlices()[ptAkaze.class_id];
if (_bOrientation)
akaze.Compute_Main_Orientation(ptAkaze, cur_slice.Lx, cur_slice.Ly);
else
ptAkaze.angle = 0.0f;
regionsCasted->Features()[i] =
SIOPointFeature(ptAkaze.x, ptAkaze.y, ptAkaze.size, ptAkaze.angle);
ComputeMSURFDescriptor(cur_slice.Lx, cur_slice.Ly, ptAkaze.octave,
regionsCasted->Features()[i],
regionsCasted->Descriptors()[i]);
}
}
break;
case AKAZE_LIOP:
{
// Build alias to cached data
AKAZE_Liop_Regions * regionsCasted = dynamic_cast<AKAZE_Liop_Regions*>(regions.get());
regionsCasted->Features().resize(kpts.size());
regionsCasted->Descriptors().resize(kpts.size());
// Init LIOP extractor
LIOP::Liop_Descriptor_Extractor liop_extractor;
#ifdef OPENMVG_USE_OPENMP
#pragma omp parallel for
#endif
for (int i = 0; i < static_cast<int>(kpts.size()); ++i)
{
AKAZEKeypoint ptAkaze = kpts[i];
// Feature masking
if (mask)
{
const image::Image<unsigned char> & maskIma = *mask;
if (maskIma(ptAkaze.y, ptAkaze.x) > 0)
continue;
}
const TEvolution & cur_slice = akaze.getSlices()[ptAkaze.class_id];
if (_bOrientation)
akaze.Compute_Main_Orientation(ptAkaze, cur_slice.Lx, cur_slice.Ly);
else
ptAkaze.angle = 0.0f;
regionsCasted->Features()[i] =
SIOPointFeature(ptAkaze.x, ptAkaze.y, ptAkaze.size, ptAkaze.angle);
// Compute LIOP descriptor (do not need rotation computation, since
// LIOP descriptor is rotation invariant).
// Rescale for LIOP patch extraction
const SIOPointFeature fp =
SIOPointFeature(ptAkaze.x, ptAkaze.y,
ptAkaze.size/2.0, ptAkaze.angle);
float desc[144];
liop_extractor.extract(image, fp, desc);
for(int j=0; j < 144; ++j)
regionsCasted->Descriptors()[i][j] =
static_cast<unsigned char>(desc[j] * 255.f +.5f);
}
}
break;
case AKAZE_MLDB:
{
// Build alias to cached data
AKAZE_Binary_Regions * regionsCasted = dynamic_cast<AKAZE_Binary_Regions*>(regions.get());
regionsCasted->Features().resize(kpts.size());
regionsCasted->Descriptors().resize(kpts.size());
#ifdef OPENMVG_USE_OPENMP
#pragma omp parallel for
#endif
for (int i = 0; i < static_cast<int>(kpts.size()); ++i)
{
AKAZEKeypoint ptAkaze = kpts[i];
// Feature masking
if (mask)
{
const image::Image<unsigned char> & maskIma = *mask;
if (maskIma(ptAkaze.y, ptAkaze.x) > 0)
continue;
}
const TEvolution & cur_slice = akaze.getSlices()[ptAkaze.class_id];
if (_bOrientation)
akaze.Compute_Main_Orientation(ptAkaze, cur_slice.Lx, cur_slice.Ly);
else
ptAkaze.angle = 0.0f;
regionsCasted->Features()[i] =
SIOPointFeature(ptAkaze.x, ptAkaze.y, ptAkaze.size, ptAkaze.angle);
// Compute MLDB descriptor
Descriptor<bool,486> desc;
ComputeMLDBDescriptor(cur_slice.cur, cur_slice.Lx, cur_slice.Ly,
ptAkaze.octave, regionsCasted->Features()[i], desc);
// convert the bool vector to the binary unsigned char array
unsigned char * ptr = reinterpret_cast<unsigned char*>(®ionsCasted->Descriptors()[i]);
memset(ptr, 0, regionsCasted->DescriptorLength()*sizeof(unsigned char));
// For each byte
for (int j = 0; j < std::ceil(486./8.); ++j, ++ptr) {
// set the corresponding 8bits to the good values
for (int iBit = 0; iBit < 8 && j*8+iBit < 486; ++iBit) {
*ptr |= desc[j*8+iBit] << iBit;
}
}
}
}
break;
}
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;
};
