我一直在尝试开发一个简单的功能跟踪程序。用户用鼠标勾勒出屏幕上的区域，并为该区域创建一个掩码并传递给goodFeaturesToTrack。然后，该功能找到的功能将在屏幕上绘制（由蓝色圆圈表示）。
接下来，我将函数返回的特征向量传递给calcOpticalFlowPyrLk，并在屏幕上绘制得到的点矢量（用绿色圆圈表示）。虽然程序正确跟踪流的方向，但由于某种原因，calcOpticalFlow功能输出的功能不与屏幕上对象的位置对齐。
我觉得这在我使用的逻辑中是一个小错误，但我似乎无法分解它，我真的很感激你们的一些帮助。
我已在下面发布了我的代码，我想为全局变量和凌乱的结构道歉。我现在只是在测试，并计划在我运行后立即清理并转换为OOP格式。
同样，我上传的YouTube视频的link也显示了我正在对抗的行为。
bool drawingBox = false;
bool destroyBox = false;
bool targetAcquired = false;
bool featuresFound = false;
CvRect box;
int boxCounter = 0;
cv::Point objectLocation;
cv::Mat prevFrame, nextFrame, prevFrame_1C, nextFrame_1C;
std::vector<cv::Point2f> originalFeatures, newFeatures, baseFeatures;
std::vector<uchar> opticalFlowFeatures;
std::vector<float> opticalFlowFeaturesError;
cv::TermCriteria opticalFlowTermination = cv::TermCriteria(CV_TERMCRIT_ITER | CV_TERMCRIT_EPS, 20, 0.3);
cv::Mat mask;
cv::Mat clearMask;
long currentFrame = 0;
void draw(cv::Mat image, CvRect rectangle)
{
if (drawingBox)
{
cv::rectangle(image, cv::Point(box.x, box.y), cv::Point(box.x + box.width, box.y + box.height), cv::Scalar(225, 238 , 81), 2);
CvRect rectangle2 = cvRect(box.x, box.y, box.width, box.height);
}
if (featuresFound)
{
for (int i = 0; i < originalFeatures.size(); i++)
{
cv::circle(image, baseFeatures[i], 4, cv::Scalar(255, 0, 0), 1, 8, 0);
cv::circle(image, newFeatures[i], 4, cv::Scalar(0, 255, 0),1, 8, 0);
cv::line(image, baseFeatures[i], newFeatures[i], cv::Scalar(255, 0, 0), 2, CV_AA);
}
}
}
void findFeatures(cv::Mat mask)
{
if (!featuresFound && targetAcquired)
{
cv::goodFeaturesToTrack(prevFrame_1C, baseFeatures, 200, 0.1, 0.1, mask);
originalFeatures= baseFeatures;
featuresFound = true;
std::cout << "Number of Corners Detected: " << originalFeatures.size() << std::endl;
for(int i = 0; i < originalFeatures.size(); i++)
{
std::cout << "Corner Location " << i << ": " << originalFeatures[i].x << "," << originalFeatures[i].y << std::endl;
}
}
}
void trackFeatures()
{
cv::calcOpticalFlowPyrLK(prevFrame_1C, nextFrame_1C, originalFeatures, newFeatures, opticalFlowFeatures, opticalFlowFeaturesError, cv::Size(30,30), 5, opticalFlowTermination);
originalFeatures = newFeatures;
}
void mouseCallback(int event, int x, int y, int flags, void *param)
{
cv::Mat frame;
frame = *((cv::Mat*)param);
switch(event)
{
case CV_EVENT_MOUSEMOVE:
{
if(drawingBox)
{
box.width = x-box.x;
box.height = y-box.y;
}
}
break;
case CV_EVENT_LBUTTONDOWN:
{
drawingBox = true;
box = cvRect (x, y, 0, 0);
targetAcquired = false;
cv::destroyWindow("Selection");
}
break;
case CV_EVENT_LBUTTONUP:
{
drawingBox = false;
featuresFound = false;
boxCounter++;
std::cout << "Box " << boxCounter << std::endl;
std::cout << "Box Coordinates: " << box.x << "," << box.y << std::endl;
std::cout << "Box Height: " << box.height << std::endl;
std::cout << "Box Width: " << box.width << std:: endl << std::endl;
if(box.width < 0)
{
box.x += box.width;
box.width *= -1;
}
if(box.height < 0)
{
box.y +=box.height;
box.height *= -1;
}
objectLocation.x = box.x;
objectLocation.y = box.y;
targetAcquired = true;
}
break;
case CV_EVENT_RBUTTONUP:
{
destroyBox = true;
}
break;
}
}
int main ()
{
const char *name = "Boundary Box";
cv::namedWindow(name);
cv::VideoCapture camera;
cv::Mat cameraFrame;
int cameraNumber = 0;
camera.open(cameraNumber);
camera >> cameraFrame;
cv::Mat mask = cv::Mat::zeros(cameraFrame.size(), CV_8UC1);
cv::Mat clearMask = cv::Mat::zeros(cameraFrame.size(), CV_8UC1);
if (!camera.isOpened())
{
std::cerr << "ERROR: Could not access the camera or video!" << std::endl;
}
cv::setMouseCallback(name, mouseCallback, &cameraFrame);
while(true)
{
if (destroyBox)
{
cv::destroyAllWindows();
break;
}
camera >> cameraFrame;
if (cameraFrame.empty())
{
std::cerr << "ERROR: Could not grab a camera frame." << std::endl;
exit(1);
}
camera.set(CV_CAP_PROP_POS_FRAMES, currentFrame);
camera >> prevFrame;
cv::cvtColor(prevFrame, prevFrame_1C, cv::COLOR_BGR2GRAY);
camera.set(CV_CAP_PROP_POS_FRAMES, currentFrame ++);
camera >> nextFrame;
cv::cvtColor(nextFrame, nextFrame_1C, cv::COLOR_BGR2GRAY);
if (targetAcquired)
{
cv::Mat roi (mask, cv::Rect(box.x, box.y, box.width, box.height));
roi = cv::Scalar(255, 255, 255);
findFeatures(mask);
clearMask.copyTo(mask);
trackFeatures();
}
draw(cameraFrame, box);
cv::imshow(name, cameraFrame);
cv::waitKey(20);
}
cv::destroyWindow(name);
return 0;
}
答案 0 :(得分：1)
在我看来，您无法在网络摄像头上使用camera.set(CV_CAP_PROP_POS_FRAMES, currentFrame)，但我对此并不乐观。
相反，我建议您将前一帧保存在prevFrame变量中。
作为一个例子，我可以建议你这个工作代码，我只在while循环中更改，并在我添加之前添加注释：
while(true)
{
if (destroyBox)
{
cv::destroyAllWindows();
break;
}
camera >> cameraFrame;
if (cameraFrame.empty())
{
std::cerr << "ERROR: Could not grab a camera frame." << std::endl;
exit(1);
}
// new lines
if(prevFrame.empty()){
prevFrame = cameraFrame;
continue;
}
// end new lines
//camera.set(CV_CAP_PROP_POS_FRAMES, currentFrame);
//camera >> prevFrame;
cv::cvtColor(prevFrame, prevFrame_1C, cv::COLOR_BGR2GRAY);
//camera.set(CV_CAP_PROP_POS_FRAMES, currentFrame ++);
//camera >> nextFrame;
// new line
nextFrame = cameraFrame;
cv::cvtColor(nextFrame, nextFrame_1C, cv::COLOR_BGR2GRAY);
if (targetAcquired)
{
cv::Mat roi (mask, cv::Rect(box.x, box.y, box.width, box.height));
roi = cv::Scalar(255, 255, 255);
findFeatures(mask);
clearMask.copyTo(mask);
trackFeatures();
}
draw(cameraFrame, box);
cv::imshow(name, cameraFrame);
cv::waitKey(20);
// old = new
// new line
prevFrame = cameraFrame.clone();
}