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Merge pull request #18037 from danielenricocahall:improve-brisk-init-perf

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This commit is contained in:
Alexander Alekhin 2020-08-18 20:06:17 +00:00
commit 2c1f3487a4
1 changed files with 58 additions and 36 deletions
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94
modules/features2d/src/brisk.cpp
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@ -353,13 +353,30 @@ BRISK_Impl::generateKernel(const std::vector<float> &radiusList,
const int rings = (int)radiusList.size();
CV_Assert(radiusList.size() != 0 && radiusList.size() == numberList.size());
points_ = 0; // remember the total number of points
double sineThetaLookupTable[n_rot_];
double cosThetaLookupTable[n_rot_];
for (int ring = 0; ring < rings; ring++)
{
points_ += numberList[ring];
}
// using a sine/cosine approximation for the lookup table
// utilizes the trig identities:
// sin(a + b) = sin(a)cos(b) + cos(a)sin(b)
// cos(a + b) = cos(a)cos(b) - sin(a)sin(b)
// and the fact that sin(0) = 0, cos(0) = 1
double cosval = 1., sinval = 0.;
double dcos = cos(2*CV_PI/double(n_rot_)), dsin = sin(2*CV_PI/double(n_rot_));
for( size_t rot = 0; rot < n_rot_; ++rot)
{
sineThetaLookupTable[rot] = sinval;
cosThetaLookupTable[rot] = cosval;
double t = sinval*dcos + cosval*dsin;
cosval = cosval*dcos - sinval*dsin;
sinval = t;
}
// 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));
@ -370,46 +387,51 @@ BRISK_Impl::generateKernel(const std::vector<float> &radiusList,
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]));
for (unsigned int scale = 0; scale < scales_; ++scale) {
scaleList_[scale] = (float) std::pow((double) 2.0, (double) (scale * lb_scale_step));
sizeList_[scale] = 0;
BriskPatternPoint *patternIteratorOuter = patternPoints_ + (scale * n_rot_ * points_);
// generate the pattern points look-up
for (int ring = 0; ring < rings; ++ring) {
double scaleRadiusProduct = scaleList_[scale] * radiusList[ring];
float patternSigma = 0.0f;
if (ring == 0) {
patternSigma = sigma_scale * scaleList_[scale] * 0.5f;
} else {
patternSigma = (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;
const unsigned int size = cvCeil(((scaleList_[scale] * radiusList[ring]) + patternSigma)) + 1;
if (sizeList_[scale] < size) {
sizeList_[scale] = size;
}
for (int num = 0; num < numberList[ring]; ++num) {
BriskPatternPoint *patternIterator = patternIteratorOuter;
double alpha = (double(num)) * 2 * CV_PI / double(numberList[ring]);
double sine_alpha = sin(alpha);
double cosine_alpha = cos(alpha);
// increment the iterator
++patternIterator;
}
for (size_t rot = 0; rot < n_rot_; ++rot) {
double cosine_theta = cosThetaLookupTable[rot];
double sine_theta = sineThetaLookupTable[rot];
// the actual coordinates on the circle
// sin(a + b) = sin(a) cos(b) + cos(a) sin(b)
// cos(a + b) = cos(a) cos(b) - sin(a) sin(b)
patternIterator->x = (float) (scaleRadiusProduct *
(cosine_theta * cosine_alpha -
sine_theta * sine_alpha)); // feature rotation plus angle of the point
patternIterator->y = (float) (scaleRadiusProduct *
(sine_theta * cosine_alpha + cosine_theta * sine_alpha));
patternIterator->sigma = patternSigma;
// and the gaussian kernel sigma
// increment the iterator
patternIterator += points_;
}
++patternIteratorOuter;
}
}
}
}
// now also generate pairings