1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
|
/* 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;
PointExtractor::PointExtractor(){
//if (!AllocConsole()){}
//else SetConsoleTitle("debug");
//freopen("CON", "w", stdout);
//freopen("CON", "w", stderr);
}
// ----------------------------------------------------------------------------
const vector<Vec2f>& PointExtractor::extract_points(Mat frame, float /*dt*/, bool draw_output)
{
const int W = frame.cols;
const int H = frame.rows;
if (frame_last.cols != W || frame_last.rows != H)
{
frame_last = cv::Mat();
}
// clear old points
points.clear();
// convert to grayscale
Mat frame_gray;
cvtColor(frame, frame_gray, CV_RGB2GRAY);
int secondary = threshold_secondary_val;
// mask for everything that passes the threshold (or: the upper threshold of the hysteresis)
Mat frame_bin;
// only used if draw_output
Mat frame_bin_copy;
// mask for everything that passes
Mat frame_bin_low;
// mask for lower-threshold && combined result of last, needs to remain in scope until drawing, but is only used if secondary != 0
Mat frame_last_and_low;
if(secondary==0){
threshold(frame_gray, frame_bin, threshold_val, 255, THRESH_BINARY);
}else{
// we recombine a number of buffers, this might be slower than a single loop of per-pixel logic
// but it might as well be faster if openCV makes good use of SIMD
float t = threshold_val;
//float hyst = float(threshold_secondary_val)/512.;
//threshold(frame_gray, frame_bin, (t + ((255.-t)*hyst)), 255, THRESH_BINARY);
float hyst = float(threshold_secondary_val)/256.;
threshold(frame_gray, frame_bin, t, 255, THRESH_BINARY);
threshold(frame_gray, frame_bin_low,std::max(float(1), t - (t*hyst)), 255, THRESH_BINARY);
if(draw_output) frame_bin.copyTo(frame_bin_copy);
if(frame_last.empty()){
frame_bin.copyTo(frame_last);
}else{
// keep pixels from last if they are above lower threshold
bitwise_and(frame_last, frame_bin_low, frame_last_and_low);
// union of pixels >= higher threshold and pixels >= lower threshold
bitwise_or(frame_bin, frame_last_and_low, frame_last);
frame_last.copyTo(frame_bin);
}
}
unsigned int region_size_min = 3.14*min_size*min_size/4.0;
unsigned int region_size_max = 3.14*max_size*max_size/4.0;
int blob_index = 1;
for (int y=0; y<H; y++)
{
if (blob_index >= 255) break;
for (int x=0; x<W; x++)
{
if (blob_index >= 255) break;
// find connected components with floodfill
if (frame_bin.at<unsigned char>(y,x) != 255) continue;
Rect rect;
floodFill(frame_bin, Point(x,y), Scalar(blob_index), &rect, Scalar(0), Scalar(0), FLOODFILL_FIXED_RANGE);
blob_index++;
// calculate the size of the connected component
unsigned int region_size = 0;
for (int i=rect.y; i < (rect.y+rect.height); i++)
{
for (int j=rect.x; j < (rect.x+rect.width); j++)
{
if (frame_bin.at<unsigned char>(i,j) != blob_index-1) continue;
region_size++;
}
}
if (region_size < region_size_min || region_size > region_size_max) continue;
// calculate the center of mass:
// mx = (sum_ij j*f(frame_grey_ij)) / (sum_ij f(frame_grey_ij))
// my = ...
// f maps from [threshold,256] -> [0, 1], lower values are mapped to 0
float m = 0;
float mx = 0;
float my = 0;
for (int i=rect.y; i < (rect.y+rect.height); i++)
{
for (int j=rect.x; j < (rect.x+rect.width); j++)
{
if (frame_bin.at<unsigned char>(i,j) != blob_index-1) continue;
float val;
if(secondary==0){
val = frame_gray.at<unsigned char>(i,j);
val = float(val - threshold_val)/(256 - threshold_val);
val = val*val; // makes it more stable (less emphasis on low values, more on the peak)
}else{
//hysteresis point detection gets stability from ignoring pixel noise so we decidedly leave the actual pixel values out of the picture
val = frame_last.at<unsigned char>(i,j) / 256.;
}
m += val;
mx += j * val;
my += i * val;
}
}
// convert to centered camera coordinate system with y axis upwards
Vec2f c;
c[0] = (mx/m - W/2)/W;
c[1] = -(my/m - H/2)/W;
//qDebug()<<blob_index<<" => "<<c[0]<<" "<<c[1];
points.push_back(c);
}
}
// draw output image
if (draw_output) {
vector<Mat> channels;
if(secondary==0){
frame_bin.setTo(170, frame_bin);
channels.push_back(frame_gray + frame_bin);
channels.push_back(frame_gray - frame_bin);
channels.push_back(frame_gray - frame_bin);
}else{
frame_bin_copy.setTo(120, frame_bin_copy);
frame_bin_low.setTo(90, frame_bin_low);
channels.push_back(frame_gray + frame_bin_copy);
channels.push_back(frame_gray + frame_last_and_low);
channels.push_back(frame_gray + frame_bin_low);
//channels.push_back(frame_gray + frame_bin);
}
merge(channels, frame);
}
return points;
}
|
