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/* Copyright (c) 2012 Patrick Ruoff
*
* Permission to use, copy, modify, and/or distribute this software for any
* purpose with or without fee is hereby granted, provided that the above
* copyright notice and this permission notice appear in all copies.
*/
#include "point_extractor.h"
#include <QDebug>
using namespace cv;
using namespace std;
struct BlobInfo
{
BlobInfo() : m00(0), m10(0), m01(0) {}
long m00;
long m10;
long m01;
};
// ----------------------------------------------------------------------------
const vector<Vec2f>& PointExtractor::extract_points(Mat frame, float dt, bool draw_output)
{
/*
// sensitivity test for tracker
static int n = 0;
if (points.size() == 3)
{
for (int i=0; i<3; ++i)
{
points[i][0] -= 1e-4*sin(n/100.0);
points[i][1] -= 1e-4*cos(n/100.0);
}
++n;
return points;
}
*/
// convert to grayscale
Mat frame_bw;
cvtColor(frame, frame_bw, CV_RGB2GRAY);
// convert to binary
threshold(frame_bw, frame_bw, threshold_val, 255, THRESH_BINARY);
//erode(frame_bw, frame_bw, Mat(), Point(-1,-1), min_size); //destroys information -> bad for subpixel accurarcy
// find connected components...
// extract blobs with floodfill
vector<BlobInfo> blobs;
int blob_count = 1;
for (int y=0; y < frame_bw.rows; y++) {
for (int x=0; x < frame_bw.cols; x++) {
if (frame_bw.at<unsigned char>(y,x) != 255) continue;
Rect rect;
floodFill(frame_bw, Point(x,y), Scalar(blob_count), &rect, Scalar(0), Scalar(0), 4);
BlobInfo blob;
for (int i=rect.y; i < (rect.y+rect.height); i++) {
for (int j=rect.x; j < (rect.x+rect.width); j++) {
if (frame_bw.at<unsigned char>(i,j) != blob_count) continue;
blob.m00++;
blob.m01+=i;
blob.m10+=j;
}
}
blobs.push_back(blob);
blob_count++;
if (blob_count >= 255) break;
}
if (blob_count >= 255) break;
}
// extract points
Vec2f c;
points.clear();
float m00_min = 3.14*min_size*min_size;
float m00_max = 3.14*max_size*max_size;
for (vector<BlobInfo>::iterator iter = blobs.begin();
iter!= blobs.end();
++iter)
{
const BlobInfo& m = *iter;
if (m.m00 < m00_min || m.m00 > m00_max) continue;
// convert to centered camera coordinate system with y axis upwards
c[0] = (m.m10/float(m.m00) - frame.cols/2)/frame.cols;
c[1] = -(m.m01/float(m.m00) - frame.rows/2)/frame.cols;
points.push_back(c);
}
// draw output image
if (draw_output)
{
frame.setTo(Scalar(255,0,0), frame_bw);
}
return points;
}
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