Question

我在我的形象上打下了圈子,我想找到圈子和具体轮.点。

How would I go about finding the intersecting points between a contour and a circle?

增编

Answer 1

Ok, here is an idea of how you could do it:

If you know the center of the circle and the radius, also if the contour that you have is obtained with CV_CHAIN_APPROX_NONE : Translates all the points from the chain code into points. then you can simply go through all the points of the sequence and see which ones have a distance from the center of the circle equal to the radius.(there can be more than 2 intersections)

如果无法与CV_CHAIN_APPROX_NONE取得座椅,那么,你可以按顺序检查每座两点,并处理在外面(距离高于rad)和内(距离低于rad)或圈子(l)的两点。届时,你将知道这两个要点之间的交叉点,你可以通过解决两个方程式系统来找到:

- 点在两点修建的线路上

- 点距圆环形中心,等于半径

If by any chance you don t know where the circle is or it s radius than you can get it s contour with cvFindContours and then go through each set of 2 points from the other contour and use :

    double cvPointPolygonTest(
                  const CvArr* contour,
                  CvPoint2D32f pt,
                  int measure_dist
                  );

In particular, if the argument measure_dist is nonzero then the function returns the distance to the nearest contour edge; that distance is 0 if the point is inside the contour and positive if the point is outside. If the measure_dist argument is 0 then the return values are simply + 1, – 1, or 0 depending on whether the point is inside, outside, or on an edge (or vertex), respectively. Th e contour itself can be either a sequence or an n-by-1 two-channel matrix of points.

从这里看,有2点,1个在外,1个在圈内,1个在圈内,1个在圈子上。同样,足以计算确切点。

PS:如果两条交织物至少相互交错,你就可以优化算法。可通过<条码>cvMinAreaRect2查阅。

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