how to detect circles and rectangle?

opencv中对圆检测的函数为：HoughCircles(src_gray,circles,CV_HOUGHT_GRADIENT,1,src_gray.cols/8,200,100,0,0)

circles:vector<Vec3f>

CV_HOUGHT_GRADIENT：指定检测算法，现在只有霍夫梯度算法

dp = 1:累加器图像的反比分辨率

src_gray.cols/8：检测到圆心之间的最小距离

200：Canny函数的高阈值

100：Canny函数的低阈值

0：能检测到的最小圆半径

0：能检测到的最大圆半径

用这个函数检测圆需要调节的参数很多，用多大阈值完全看经验。

rect：
http://www.pyimagesearch.com/2014/04/21/building-pokedex-python-finding-game-boy-screen-step-4-6/
circles：
https://github.com/sol-prog/OpenCV-red-circle-detection/blob/master/circle_detect.cpp https://github.com/shayanc/Hough-transform-circle-detector/blob/master/circle_detection.cpp https://github.com/neodeng/SpotsDetect https://github.com/RomainQueraud/Cplusplus-CircleDetect https://github.com/ruteee/DetectAndGoCircles https://github.com/zhengsir/Visual_Circle_Detect https://github.com/night18/circle_shape_detect https://github.com/b--dub/OpenCV_MotionDetect_Circles