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| -rw-r--r-- | shape-detect.cpp | 108 |
1 files changed, 108 insertions, 0 deletions
diff --git a/shape-detect.cpp b/shape-detect.cpp new file mode 100644 index 0000000..f373adf --- /dev/null +++ b/shape-detect.cpp @@ -0,0 +1,108 @@ +/** + * Simple shape detector program. + * It loads an image and tries to find simple shapes (rectangle, triangle, circle, etc) in it. + * This program is a modified version of `squares.cpp` found in the OpenCV sample dir. + */ +#include <opencv2/highgui/highgui.hpp> +#include <opencv2/imgproc/imgproc.hpp> +#include <cmath> + +/** + * Helper function to find a cosine of angle between vectors + * from pt0->pt1 and pt0->pt2 + */ +static double angle(cv::Point pt1, cv::Point pt2, cv::Point pt0) +{ + double dx1 = pt1.x - pt0.x; + double dy1 = pt1.y - pt0.y; + double dx2 = pt2.x - pt0.x; + double dy2 = pt2.y - pt0.y; + return (dx1*dx2 + dy1*dy2)/sqrt((dx1*dx1 + dy1*dy1)*(dx2*dx2 + dy2*dy2) + 1e-10); +} + +/** + * Helper function to display text in the center of a contour + */ +void setLabel(cv::Mat& im, const std::string label, std::vector<cv::Point>& contour) +{ + int fontface = cv::FONT_HERSHEY_SIMPLEX; + double scale = 0.4; + int thickness = 1; + int baseline = 0; + + cv::Size text = cv::getTextSize(label, fontface, scale, thickness, &baseline); + cv::Rect r = cv::boundingRect(contour); + + cv::Point pt(r.x + ((r.width - text.width) / 2), r.y + ((r.height + text.height) / 2)); + cv::rectangle(im, pt + cv::Point(0, baseline), pt + cv::Point(text.width, -text.height), CV_RGB(255,255,255), CV_FILLED); + cv::putText(im, label, pt, fontface, scale, CV_RGB(0,0,0), thickness, 8); +} + +int main() +{ + cv::Mat src = cv::imread("basic-shapes-2.png"); + if (src.empty()) + return -1; + + // Convert to grayscale + cv::Mat gray; + cv::cvtColor(src, gray, CV_BGR2GRAY); + + // Use Canny instead of threshold to catch squares with gradient shading + cv::Mat bw; + cv::Canny(gray, bw, 0, 50, 5); + + // Find contours + std::vector<std::vector<cv::Point> > contours; + cv::findContours(bw.clone(), contours, CV_RETR_EXTERNAL, CV_CHAIN_APPROX_SIMPLE); + + std::vector<cv::Point> approx; + cv::Mat dst = src.clone(); + + for (int i = 0; i < contours.size(); i++) + { + // Approximate contour with accuracy proportional + // to the contour perimeter + cv::approxPolyDP(cv::Mat(contours[i]), approx, cv::arcLength(cv::Mat(contours[i]), true)*0.02, true); + + // Skip small or non-convex objects + if (std::fabs(cv::contourArea(contours[i])) < 100 || !cv::isContourConvex(approx)) + continue; + + if (approx.size() == 3) + setLabel(dst, "TRI", contours[i]); // Triangles + else if (approx.size() == 5) + setLabel(dst, "PENTA", contours[i]); // Pentagons + else if (approx.size() == 6) + setLabel(dst, "HEXA", contours[i]); // Hexagons + else if (approx.size() == 4) + { + // Detect and label rectangles + double maxcos = 0; + for (int j = 2; j < 5; j++) + { + double cos = std::fabs(angle(approx[j%4], approx[j-2], approx[j-1])); + maxcos = std::max(maxcos, cos); + } + if (maxcos < 0.3) + setLabel(dst, "RECT", contours[i]); + } + else + { + // Detect and label circles + double area = cv::contourArea(contours[i]); + cv::Rect r = cv::boundingRect(contours[i]); + int radius = r.width / 2; + + if (std::abs(1 - ((double)r.width / r.height)) <= 0.2 && + std::abs(1 - (area / (CV_PI * std::pow(radius, 2)))) <= 0.2) + setLabel(dst, "CIR", contours[i]); + } + } + + cv::imshow("src", src); + cv::imshow("dst", dst); + cv::waitKey(0); + return 0; +} + |