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vio/CPU_version/svo/src/feature_detection.cpp
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2021-05-05 11:19:06 +02:00

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// This file is part of SVO - Semi-direct Visual Odometry.
//
// Copyright (C) 2014 Christian Forster <forster at ifi dot uzh dot ch>
// (Robotics and Perception Group, University of Zurich, Switzerland).
//
// SVO is free software: you can redistribute it and/or modify it under the
// terms of the GNU General Public License as published by the Free Software
// Foundation, either version 3 of the License, or any later version.
//
// SVO is distributed in the hope that it will be useful, but WITHOUT ANY
// WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
// FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with this program. If not, see <http://www.gnu.org/licenses/>.
#include <svo/feature_detection.h>
#include <svo/feature.h>
#include <fast/fast.h>
#include <vikit/vision.h>
namespace svo {
namespace feature_detection {
AbstractDetector::AbstractDetector(
const int img_width,
const int img_height,
const int cell_size,
const int n_pyr_levels) :
cell_size_(cell_size),
n_pyr_levels_(n_pyr_levels),
grid_n_cols_(ceil(static_cast<double>(img_width)/cell_size_)),
grid_n_rows_(ceil(static_cast<double>(img_height)/cell_size_)),
grid_occupancy_(grid_n_cols_*grid_n_rows_, false)
{}
void AbstractDetector::resetGrid()
{
std::fill(grid_occupancy_.begin(), grid_occupancy_.end(), false);
}
void AbstractDetector::setExistingFeatures(const Features& fts)
{
std::for_each(fts.begin(), fts.end(), [&](Feature* i){
grid_occupancy_.at(
static_cast<int>(i->px[1]/cell_size_)*grid_n_cols_
+ static_cast<int>(i->px[0]/cell_size_)) = true;
});
}
void AbstractDetector::setGridOccpuancy(const Vector2d& px)
{
grid_occupancy_.at(
static_cast<int>(px[1]/cell_size_)*grid_n_cols_
+ static_cast<int>(px[0]/cell_size_)) = true;
}
FastDetector::FastDetector(
const int img_width,
const int img_height,
const int cell_size,
const int n_pyr_levels) :
AbstractDetector(img_width, img_height, cell_size, n_pyr_levels)
{}
void FastDetector::detect(
Frame* frame,
const ImgPyr& img_pyr,
const double detection_threshold,
Features& fts)
{
Corners corners(grid_n_cols_*grid_n_rows_, Corner(0,0,detection_threshold,0,0.0f));
for(int L=0; L<n_pyr_levels_; ++L)
{
const int scale = (1<<L);
vector<fast::fast_xy> fast_corners;
#if __SSE2__
fast::fast_corner_detect_10_sse2(
(fast::fast_byte*) img_pyr[L].data, img_pyr[L].cols,
img_pyr[L].rows, img_pyr[L].cols, 20, fast_corners);
#elif HAVE_FAST_NEON
fast::fast_corner_detect_9_neon(
(fast::fast_byte*) img_pyr[L].data, img_pyr[L].cols,
img_pyr[L].rows, img_pyr[L].cols, 20, fast_corners);
#else
fast::fast_corner_detect_10(
(fast::fast_byte*) img_pyr[L].data, img_pyr[L].cols,
img_pyr[L].rows, img_pyr[L].cols, 20, fast_corners);
#endif
vector<int> scores, nm_corners;
fast::fast_corner_score_10((fast::fast_byte*) img_pyr[L].data, img_pyr[L].cols, fast_corners, 20, scores);
fast::fast_nonmax_3x3(fast_corners, scores, nm_corners);
for(auto it=nm_corners.begin(), ite=nm_corners.end(); it!=ite; ++it)
{
fast::fast_xy& xy = fast_corners.at(*it);
const int k = static_cast<int>((xy.y*scale)/cell_size_)*grid_n_cols_
+ static_cast<int>((xy.x*scale)/cell_size_);
if(grid_occupancy_[k])
continue;
const float score = vk::shiTomasiScore(img_pyr[L], xy.x, xy.y);
if(score > corners.at(k).score)
corners.at(k) = Corner(xy.x*scale, xy.y*scale, score, L, 0.0f);
}
}
// Create feature for every corner that has high enough corner score
std::for_each(corners.begin(), corners.end(), [&](Corner& c) {
if(c.score > detection_threshold)
fts.push_back(new Feature(frame, Vector2d(c.x, c.y), c.level));
});
resetGrid();
}
} // namespace feature_detection
} // namespace svo