I have mistake "approxPolyDP(ROI_Vertices, ROI_Poly, 1.0, true)" in OpenCV

Question

I don't know what I've done wrong.

Mat mask(img.size(), CV_8UC1, Scalar::all(0));

// Create Polygon from vertices
vector<Point> ROI_Vertices(4);
ROI_Vertices.push_back(Point(196,40));
ROI_Vertices.push_back(Point(47,450));
ROI_Vertices.push_back(Point(204,450));
ROI_Vertices.push_back(Point(275,40));

vector<Point> ROI_Poly;

approxPolyDP(ROI_Vertices, ROI_Poly, 1.0, true);

// Fill polygon white
fillConvexPoly(mask, &ROI_Poly[0], ROI_Poly.size(), 255, 8, 0);

// Create new image for result storage
Mat resImage(480, 640, CV_8UC3);

// Cut out ROI and store it in imageDest
img.copyTo(resImage, mask);
    imshow("h",img);
    imshow("hh",resImage);

I think my program recognize
ROI_Vertices have Point(0,0)

How can I fix this?

It seems that you have to read how c++ vector works – Miki Aug 24 '17 at 06:36 — Miki, Aug 24 '17 at 06:36

I.Newton · Accepted Answer · 2017-08-24T08:18:16.823

0

That's simple.Remove the points (0,0). Make the following change

ROI_Vertices.clear();

edited Aug 24 '17 at 08:18

answered Aug 24 '17 at 05:53

I.Newton

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Why do you create a vector of 4 elements in the first place then? – Miki Aug 24 '17 at 06:35

I have mistake "approxPolyDP(ROI_Vertices, ROI_Poly, 1.0, true)" in OpenCV

1 Answers1