opencv - How to detect corner with specific angle degree -


i have image equilateral triangle , rectangle:
equilateral triangle , rectangle
, want detect 3 corner of triangle only. follow opencv harris corner detector tutorial see corner-point of triangle have threshold = 80 (when 4 corner-point of rectangle threshold = 255). did not find link between threshold , degree.

how can find corner in range of [55,65] degree, example?
here output mat http://pastebin.com/raw.php?i=qnideag0

p/s: new cv, hope can give more detail!

it seems found possible solution. i've implemented on mathematica , able explain basic steps.

  1. use find corners operator , take strongest corners. use harris operator. corners

  2. find contours (cv::findcontours).

    contours

  3. for each corner in each contour draw circle , find point of intersection between circle , contour. there no ready function in opencv , should implement yourself.

    intersections

  4. now each corner have coordinates of 3 points: corner, , 2 points on sides of contour. enough evaluate angles using dot product:

    angle estimation

result:

corners found


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