From 35d63083f98685e0b96fbae79db203ed783d672f Mon Sep 17 00:00:00 2001
From: Alexey Spizhevoy <no@email>
Date: Mon, 20 Feb 2012 08:31:10 +0000
Subject: [PATCH] Added Farneback's optical flow sample

---
 samples/gpu/farneback_optical_flow.cpp | 133 +++++++++++++++++++++++++++++++++
 1 file changed, 133 insertions(+)
 create mode 100644 samples/gpu/farneback_optical_flow.cpp

diff --git a/samples/gpu/farneback_optical_flow.cpp b/samples/gpu/farneback_optical_flow.cpp
new file mode 100644
index 0000000..a88b2da
--- /dev/null
+++ b/samples/gpu/farneback_optical_flow.cpp
@@ -0,0 +1,133 @@
+#include <iostream>
+#include <vector>
+#include <sstream>
+
+#include "opencv2/core/core.hpp"
+#include "opencv2/highgui/highgui.hpp"
+#include "opencv2/video/video.hpp"
+#include "opencv2/gpu/gpu.hpp"
+
+using namespace std;
+using namespace cv;
+using namespace cv::gpu;
+
+template <typename T>
+inline T mapVal(T x, T a, T b, T c, T d)
+{
+    x = ::max(::min(x, b), a);
+    return c + (d-c) * (x-a) / (b-a);
+}
+
+void colorizeFlow(const Mat &u, const Mat &v, Mat &dst)
+{
+    double uMin, uMax;
+    minMaxLoc(u, &uMin, &uMax, 0, 0);
+    double vMin, vMax;
+    minMaxLoc(v, &vMin, &vMax, 0, 0);
+    uMin = ::abs(uMin); uMax = ::abs(uMax);
+    vMin = ::abs(vMin); vMax = ::abs(vMax);
+    float dMax = ::max(::max(uMin, uMax), ::max(vMin, vMax));
+
+    dst.create(u.size(), CV_8UC3);
+    for (int y = 0; y < u.rows; ++y)
+    {
+        for (int x = 0; x < u.cols; ++x)
+        {
+            dst.at<uchar>(y,3*x) = 0;
+            dst.at<uchar>(y,3*x+1) = (uchar)mapVal(-v.at<float>(y,x), -dMax, dMax, 0.f, 255.f);
+            dst.at<uchar>(y,3*x+2) = (uchar)mapVal(u.at<float>(y,x), -dMax, dMax, 0.f, 255.f);
+        }
+    }
+}
+
+int main(int argc, char **argv)
+{
+    CommandLineParser cmd(argc, argv,
+            "{ l | left | | specify left image }"
+            "{ r | right | | specify right image }"
+            "{ h | help | false | print help message }");
+
+    if (cmd.get<bool>("help"))
+    {
+        cout << "Farneback's optical flow sample.\n\n"
+             << "Usage: farneback_optical_flow_gpu [arguments]\n\n"
+             << "Arguments:\n";
+        cmd.printParams();
+        return 0;
+    }
+
+    string pathL = cmd.get<string>("left");
+    string pathR = cmd.get<string>("right");
+    if (pathL.empty()) cout << "Specify left image path\n";
+    if (pathR.empty()) cout << "Specify right image path\n";
+    if (pathL.empty() || pathR.empty()) return -1;
+
+    Mat frameL = imread(pathL, IMREAD_GRAYSCALE);
+    Mat frameR = imread(pathR, IMREAD_GRAYSCALE);
+    if (frameL.empty()) cout << "Can't open '" << pathL << "'\n";
+    if (frameR.empty()) cout << "Can't open '" << pathR << "'\n";
+    if (frameL.empty() || frameR.empty()) return -1;
+
+    GpuMat d_frameL(frameL), d_frameR(frameR);
+    GpuMat d_flowx, d_flowy;
+    FarnebackOpticalFlow d_calc;
+    Mat flowxy, flowx, flowy, image;
+
+    bool running = true, gpuMode = true;
+    int64 t, t0=0, t1=1, tc0, tc1;
+
+    cout << "Use 'm' for CPU/GPU toggling\n";
+
+    while (running)
+    {
+        t = getTickCount();
+
+        if (gpuMode)
+        {
+            tc0 = getTickCount();
+            d_calc(d_frameL, d_frameR, d_flowx, d_flowy);
+            tc1 = getTickCount();
+            d_flowx.download(flowx);
+            d_flowy.download(flowy);
+        }
+        else
+        {
+            tc0 = getTickCount();
+            calcOpticalFlowFarneback(
+                        frameL, frameR, flowxy, d_calc.pyrScale, d_calc.numLevels, d_calc.winSize,
+                        d_calc.numIters, d_calc.polyN, d_calc.polySigma, d_calc.flags);
+            tc1 = getTickCount();
+
+            Mat planes[] = {flowx, flowy};
+            split(flowxy, planes);
+            flowx = planes[0]; flowy = planes[1];
+        }
+
+        colorizeFlow(flowx, flowy, image);
+
+        stringstream s;
+        s << "mode: " << (gpuMode?"GPU":"CPU");
+        putText(image, s.str(), Point(5, 25), FONT_HERSHEY_SIMPLEX, 1., Scalar(255,0,255), 2);
+
+        s.str("");
+        s << "opt. flow FPS: " << cvRound((getTickFrequency()/(tc1-tc0)));
+        putText(image, s.str(), Point(5, 65), FONT_HERSHEY_SIMPLEX, 1., Scalar(255,0,255), 2.);
+
+        s.str("");
+        s << "total FPS: " << cvRound((getTickFrequency()/(t1-t0)));
+        putText(image, s.str(), Point(5, 105), FONT_HERSHEY_SIMPLEX, 1., Scalar(255,0,255), 2.);
+
+        imshow("flow", image);
+
+        char ch = (char)waitKey(3);
+        if (ch == 27)
+            running = false;
+        else if (ch == 'm' || ch == 'M')
+            gpuMode = !gpuMode;
+
+        t0 = t;
+        t1 = getTickCount();
+    }
+
+    return 0;
+}
-- 
2.7.4