I want to use the calcOptialFlowPyrLK to track FAST feature points and use non-maximum suppression to select feature points. But what does it mean now? OpenCV Error: Assertion failed ((npoints = prevPtsMat.checkVector(2, CV_32F, true)) >= 0) in calcOpticalFlowPyrLK, file /home/jiaxw/opencv/opencv-3.1.0/modules/video/src/lkpyramid.cpp, line 1114 terminate called after throwing an instance of 'cv::Exception' what(): /home/jiaxw/opencv/opencv-3.1.0/modules/video/src/lkpyramid.cpp:1114: error: (-215) (npoints = prevPtsMat.checkVector(2, CV_32F, true)) >= 0 in function calcOpticalFlowPyrLK
Here is my code:
include <iostream>
include <fstream>
include <list>
include <vector>
include <chrono>
using namespace std;
include <opencv2 core="" core.hpp="">
include <opencv2 highgui="" highgui.hpp="">
include <opencv2 features2d="" features2d.hpp="">
include <opencv2 video="" tracking.hpp="">
void selectMax( int window, cv::Mat gray, std::vector<cv::keypoint> & kp_0){ int r = window /2; if( window != 0) {
for( int i = 0; i < kp_0.size(); i++){
for( int j = 0; j < kp_0.size(); j++)
{
if( (abs(kp_0[i].pt.x - kp_0[j].pt.x) + abs(kp_0[i].pt.y - kp_0[j].pt.y) ) <= 2*r){
if( kp_0[i].response < kp_0[j].response){
std::vector<cv::KeyPoint>:: iterator it = kp_0.begin() + i;
kp_0.erase(it);
selectMax(window, gray, kp_0);
}
else{
std::vector<cv::KeyPoint>::iterator it = kp_0.begin() + j;
kp_0.erase(it);
selectMax(window, gray, kp_0);
}
}
}
}
}
}
int main( int argc, char** argv ) { if ( argc != 2 ) { cout<<"usage: useLK path_to_dataset"<<endl; return="" 1;="" }="" string="" path_to_dataset="argv[1];" string="" associate_file="path_to_dataset" +="" "="" associate.txt";<="" p="">
ifstream fin( associate_file );
if ( !fin )
{
cerr<<"I cann't find associate.txt!"<<endl;
return 1;
}
string rgb_file, depth_file, time_rgb, time_depth;
list< cv::Point2f > keypoints;
cv::Mat color, depth, last_color;
for ( int index=0; index<800; index++ )
{
fin>>time_rgb>>rgb_file>>time_depth>>depth_file;
color = cv::imread( path_to_dataset+"/"+rgb_file );
depth = cv::imread( path_to_dataset+"/"+depth_file, -1 );
std::vector<cv::KeyPoint> kp;
cv::Mat gray;
cv::cvtColor( color, gray, cv::COLOR_BGR2GRAY);
if (index ==0 )
{
std::vector<cv::KeyPoint> kps;
std::vector<cv::KeyPoint>kp_select;
cv::Ptr<cv::FastFeatureDetector> detector = cv::FastFeatureDetector::create();
detector->detect( color, kps );
int window = 7;
selectMax(window, gray, kps);
kp_select.assign(kps.begin(), kps.end());
for ( auto kp:kp_select )
keypoints.push_back( kp.pt );
last_color = color;
continue;
}
if ( color.data==nullptr || depth.data==nullptr )
continue;
vector<cv::Point2f> next_keypoints;
vector<cv::Point2f> prev_keypoints;
for ( auto kp:keypoints )
prev_keypoints.push_back(kp);
vector<unsigned char> status;
vector<float> error;
chrono::steady_clock::time_point t1 = chrono::steady_clock::now();
cv::calcOpticalFlowPyrLK( last_color, color, prev_keypoints, next_keypoints, status, error );
chrono::steady_clock::time_point t2 = chrono::steady_clock::now();
chrono::duration<double> time_used = chrono::duration_cast<chrono::duration<double>>( t2-t1 );
cout<<"LK Flow use time："<<time_used.count()<<" seconds."<<endl;
int i=0;
for ( auto iter=keypoints.begin(); iter!=keypoints.end(); i++)
{
if ( status[i] == 0 )
{
iter = keypoints.erase(iter);
continue;
}
*iter = next_keypoints[i];
iter++;
}
cout<<"tracked keypoints: "<<keypoints.size()<<endl;
if (keypoints.size() == 0)
{
cout<<"all keypoints are lost."<<endl;
break;
}
cv::Mat img_show = color.clone();
for ( auto kp:keypoints )
cv::circle(img_show, kp, 10, cv::Scalar(0, 240, 0), 1);
cv::imshow("corners", img_show);
cv::waitKey(0);
last_color = color;
}
return 0;
}
