您好.. 我遇到了矩形检测问题,它的边不规则(不直),如上图所示。实际上,使用方法 houghline 可以通过一些参数配置来检测矩形上的线。在计算相交并得到 4 个角后,我可以将它旋转到正常位置。
但是如果我把图像换成另一个矩形(不同大小但仍然有不规则的边),我需要重新配置参数。这是因为四边都没有检测到线,而且线可以超过4条。
除了houghline还有其他方法更简单(不需要重新配置/困难配置)吗?
最佳答案
这种方法是计算包含所有矩形像素的旋转矩形。
也许你可以将它与 vasanth 的答案结合起来,这样你就可以首先近似多项式以获得规则边界,然后使用 cv::minAreaRect
这是我的代码:
int main()
{
cv::Mat input = cv::imread("../inputData/RotatedRect.png");
// convert to grayscale (you could load as grayscale instead)
cv::Mat gray;
cv::cvtColor(input,gray, CV_BGR2GRAY);
// compute mask (you could use a simple threshold if the image is always as good as the one you provided)
cv::Mat mask;
cv::threshold(gray, mask, 0, 255, CV_THRESH_BINARY_INV | CV_THRESH_OTSU);
// find contours (if always so easy to segment as your image, you could just add the black/rect pixels to a vector)
std::vector<std::vector<cv::Point>> contours;
std::vector<cv::Vec4i> hierarchy;
cv::findContours(mask,contours, CV_RETR_EXTERNAL, CV_CHAIN_APPROX_SIMPLE);
/// Draw contours and find biggest contour (if there are other contours in the image, we assume the biggest one is the desired rect)
// drawing here is only for demonstration!
int biggestContourIdx = -1;
float biggestContourArea = 0;
cv::Mat drawing = cv::Mat::zeros( mask.size(), CV_8UC3 );
for( int i = 0; i< contours.size(); i++ )
{
cv::Scalar color = cv::Scalar(0, 100, 0);
drawContours( drawing, contours, i, color, 1, 8, hierarchy, 0, cv::Point() );
float ctArea= cv::contourArea(contours[i]);
if(ctArea > biggestContourArea)
{
biggestContourArea = ctArea;
biggestContourIdx = i;
}
}
// if no contour found
if(biggestContourIdx < 0)
{
std::cout << "no contour found" << std::endl;
return 1;
}
// compute the rotated bounding rect of the biggest contour! (this is the part that does what you want/need)
cv::RotatedRect boundingBox = cv::minAreaRect(contours[biggestContourIdx]);
// one thing to remark: this will compute the OUTER boundary box, so maybe you have to erode/dilate if you want something between the ragged lines
// draw the rotated rect
cv::Point2f corners[4];
boundingBox.points(corners);
cv::line(drawing, corners[0], corners[1], cv::Scalar(255,255,255));
cv::line(drawing, corners[1], corners[2], cv::Scalar(255,255,255));
cv::line(drawing, corners[2], corners[3], cv::Scalar(255,255,255));
cv::line(drawing, corners[3], corners[0], cv::Scalar(255,255,255));
// display
cv::imshow("input", input);
cv::imshow("drawing", drawing);
cv::waitKey(0);
cv::imwrite("rotatedRect.png",drawing);
return 0;
}
给出这个结果:
关于c++ - OpenCV C++ - 具有不规则边的矩形检测,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/26583649/