static inline void check_guide(kd_tree *t, int *coeffs, int off,
int *scores, int *pos)
{
if (t->start + off >= t->end) return;
int *points = t->start + off;
int attempt = patch_score(coeffs, points, t->k);
if (attempt < scores[0]) {
pos[0] = off;
scores[0] = attempt;
if (scores[0] < scores[1]) swap2(scores, pos);
}
}
bool Matcher::findEpipolarMatchDirect(
const Frame& ref_frame,
const Frame& cur_frame,
const Feature& ref_ftr,
const double d_estimate,
const double d_min,
const double d_max,
double& depth)
{
SE3 T_cur_ref = cur_frame.T_f_w_ * ref_frame.T_f_w_.inverse();
int zmssd_best = PatchScore::threshold();
Vector2d uv_best;
// Compute start and end of epipolar line in old_kf for match search, on unit plane!
Vector2d A = vk::project2d(T_cur_ref * (ref_ftr.f*d_min));
Vector2d B = vk::project2d(T_cur_ref * (ref_ftr.f*d_max));
epi_dir_ = A - B;
// Compute affine warp matrix
warp::getWarpMatrixAffine(
*ref_frame.cam_, *cur_frame.cam_, ref_ftr.px, ref_ftr.f,
d_estimate, T_cur_ref, ref_ftr.level, A_cur_ref_);
// feature pre-selection
reject_ = false;
if(ref_ftr.type == Feature::EDGELET && options_.epi_search_edgelet_filtering)
{
const Vector2d grad_cur = (A_cur_ref_ * ref_ftr.grad).normalized();
const double cosangle = fabs(grad_cur.dot(epi_dir_.normalized()));
if(cosangle < options_.epi_search_edgelet_max_angle) {
reject_ = true;
return false;
}
}
search_level_ = warp::getBestSearchLevel(A_cur_ref_, Config::nPyrLevels()-1);
// Find length of search range on epipolar line
Vector2d px_A(cur_frame.cam_->world2cam(A));
Vector2d px_B(cur_frame.cam_->world2cam(B));
epi_length_ = (px_A-px_B).norm() / (1<<search_level_);
// Warp reference patch at ref_level
warp::warpAffine(A_cur_ref_, ref_frame.img_pyr_[ref_ftr.level], ref_ftr.px,
ref_ftr.level, search_level_, halfpatch_size_+1, patch_with_border_);
createPatchFromPatchWithBorder();
if(epi_length_ < 2.0)
{
px_cur_ = (px_A+px_B)/2.0;
Vector2d px_scaled(px_cur_/(1<<search_level_));
bool res;
if(options_.align_1d)
res = feature_alignment::align1D(
cur_frame.img_pyr_[search_level_], (px_A-px_B).cast<float>().normalized(),
patch_with_border_, patch_, options_.align_max_iter, px_scaled, h_inv_);
else
res = feature_alignment::align2D(
cur_frame.img_pyr_[search_level_], patch_with_border_, patch_,
options_.align_max_iter, px_scaled);
if(res)
{
px_cur_ = px_scaled*(1<<search_level_);
if(depthFromTriangulation(T_cur_ref, ref_ftr.f, cur_frame.cam_->cam2world(px_cur_), depth))
return true;
}
return false;
}
size_t n_steps = epi_length_/0.7; // one step per pixel
Vector2d step = epi_dir_/n_steps;
if(n_steps > options_.max_epi_search_steps)
{
printf("WARNING: skip epipolar search: %zu evaluations, px_lenght=%f, d_min=%f, d_max=%f.\n",
n_steps, epi_length_, d_min, d_max);
return false;
}
// for matching, precompute sum and sum2 of warped reference patch
int pixel_sum = 0;
int pixel_sum_square = 0;
PatchScore patch_score(patch_);
// now we sample along the epipolar line
Vector2d uv = B-step;
Vector2i last_checked_pxi(0,0);
++n_steps;
for(size_t i=0; i<n_steps; ++i, uv+=step)
{
Vector2d px(cur_frame.cam_->world2cam(uv));
Vector2i pxi(px[0]/(1<<search_level_)+0.5,
px[1]/(1<<search_level_)+0.5); // +0.5 to round to closest int
if(pxi == last_checked_pxi)
continue;
last_checked_pxi = pxi;
// check if the patch is full within the new frame
if(!cur_frame.cam_->isInFrame(pxi, patch_size_, search_level_))
continue;
// TODO interpolation would probably be a good idea
uint8_t* cur_patch_ptr = cur_frame.img_pyr_[search_level_].data
+ (pxi[1]-halfpatch_size_)*cur_frame.img_pyr_[search_level_].cols
+ (pxi[0]-halfpatch_size_);
int zmssd = patch_score.computeScore(cur_patch_ptr, cur_frame.img_pyr_[search_level_].cols);
if(zmssd < zmssd_best) {
zmssd_best = zmssd;
uv_best = uv;
}
}
if(zmssd_best < PatchScore::threshold())
{
if(options_.subpix_refinement)
{
px_cur_ = cur_frame.cam_->world2cam(uv_best);
Vector2d px_scaled(px_cur_/(1<<search_level_));
bool res;
if(options_.align_1d)
res = feature_alignment::align1D(
cur_frame.img_pyr_[search_level_], (px_A-px_B).cast<float>().normalized(),
patch_with_border_, patch_, options_.align_max_iter, px_scaled, h_inv_);
else
res = feature_alignment::align2D(
cur_frame.img_pyr_[search_level_], patch_with_border_, patch_,
options_.align_max_iter, px_scaled);
if(res)
{
px_cur_ = px_scaled*(1<<search_level_);
if(depthFromTriangulation(T_cur_ref, ref_ftr.f, cur_frame.cam_->cam2world(px_cur_), depth))
return true;
}
return false;
}
px_cur_ = cur_frame.cam_->world2cam(uv_best);
if(depthFromTriangulation(T_cur_ref, ref_ftr.f, vk::unproject2d(uv_best).normalized(), depth))
return true;
}
return false;
}
