Open Source Computer Vision Library https://opencv.org/
 
 
 
 
 
 

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// This file is part of OpenCV project.
// It is subject to the license terms in the LICENSE file found in the top-level directory
// of this distribution and at http://opencv.org/license.html
#include <iostream>
#include <iomanip>
#include <vector>
#include "opencv2/core/ocl.hpp"
#include "opencv2/core/utility.hpp"
#include "opencv2/imgcodecs.hpp"
#include "opencv2/videoio.hpp"
#include "opencv2/highgui.hpp"
#include "opencv2/video.hpp"
using namespace std;
using namespace cv;
static Mat getVisibleFlow(InputArray flow)
{
vector<UMat> flow_vec;
split(flow, flow_vec);
UMat magnitude, angle;
cartToPolar(flow_vec[0], flow_vec[1], magnitude, angle, true);
magnitude.convertTo(magnitude, CV_32F, 0.2);
vector<UMat> hsv_vec;
hsv_vec.push_back(angle);
hsv_vec.push_back(UMat::ones(angle.size(), angle.type()));
hsv_vec.push_back(magnitude);
UMat hsv;
merge(hsv_vec, hsv);
Mat img;
cvtColor(hsv, img, COLOR_HSV2BGR);
return img;
}
static Size fitSize(const Size & sz, const Size & bounds)
{
CV_Assert(!sz.empty());
if (sz.width > bounds.width || sz.height > bounds.height)
{
double scale = std::min((double)bounds.width / sz.width, (double)bounds.height / sz.height);
return Size(cvRound(sz.width * scale), cvRound(sz.height * scale));
}
return sz;
}
int main(int argc, const char* argv[])
{
const char* keys =
"{ h help | | print help message }"
"{ c camera | 0 | capture video from camera (device index starting from 0) }"
"{ a algorithm | fb | algorithm (supported: 'fb', 'dis')}"
"{ m cpu | | run without OpenCL }"
"{ v video | | use video as input }"
"{ o original | | use original frame size (do not resize to 640x480)}"
;
CommandLineParser parser(argc, argv, keys);
parser.about("This sample demonstrates using of dense optical flow algorithms.");
if (parser.has("help"))
{
parser.printMessage();
return 0;
}
int camera = parser.get<int>("camera");
string algorithm = parser.get<string>("algorithm");
bool useCPU = parser.has("cpu");
string filename = parser.get<string>("video");
bool useOriginalSize = parser.has("original");
if (!parser.check())
{
parser.printErrors();
return 1;
}
VideoCapture cap;
if(filename.empty())
cap.open(camera);
else
cap.open(filename);
if (!cap.isOpened())
{
cout << "Can not open video stream: '" << (filename.empty() ? "<camera>" : filename) << "'" << endl;
return 2;
}
Ptr<DenseOpticalFlow> alg;
if (algorithm == "fb")
alg = FarnebackOpticalFlow::create();
else if (algorithm == "dis")
alg = DISOpticalFlow::create(DISOpticalFlow::PRESET_FAST);
else
{
cout << "Invalid algorithm: " << algorithm << endl;
return 3;
}
ocl::setUseOpenCL(!useCPU);
cout << "Press 'm' to toggle CPU/GPU processing mode" << endl;
cout << "Press ESC or 'q' to exit" << endl;
UMat prevFrame, frame, input_frame, flow;
for(;;)
{
if (!cap.read(input_frame) || input_frame.empty())
{
cout << "Finished reading: empty frame" << endl;
break;
}
Size small_size = fitSize(input_frame.size(), Size(640, 480));
if (!useOriginalSize && small_size != input_frame.size())
resize(input_frame, frame, small_size);
else
frame = input_frame;
cvtColor(frame, frame, COLOR_BGR2GRAY);
imshow("frame", frame);
if (!prevFrame.empty())
{
int64 t = getTickCount();
alg->calc(prevFrame, frame, flow);
t = getTickCount() - t;
{
Mat img = getVisibleFlow(flow);
ostringstream buf;
buf << "Algo: " << algorithm << " | "
<< "Mode: " << (useCPU ? "CPU" : "GPU") << " | "
<< "FPS: " << fixed << setprecision(1) << (getTickFrequency() / (double)t);
putText(img, buf.str(), Point(10, 30), FONT_HERSHEY_PLAIN, 2.0, Scalar(0, 0, 255), 2, LINE_AA);
imshow("Dense optical flow field", img);
}
}
frame.copyTo(prevFrame);
// interact with user
const char key = (char)waitKey(30);
if (key == 27 || key == 'q') // ESC
{
cout << "Exit requested" << endl;
break;
}
else if (key == 'm')
{
useCPU = !useCPU;
ocl::setUseOpenCL(!useCPU);
cout << "Set processing mode to: " << (useCPU ? "CPU" : "GPU") << endl;
}
}
return 0;
}